Filling and colour reintegration in a single step 101 was of prime consideration, and so was the potential retreatability. Despite the various options described previously, we decided on a different material, i.e. a coloured waxresin mixture. It is a system without water, and the added material can be removed from the clay support by means of appropriate solvent. The wax-resin filling contains beeswax and dammar resin. To bulk out the fill, chalk (Ca carbonate) is used. By adding pigments to the mixture, we matched the colour and achieved the satin look of the original surface of the paint layer. The use of this mixture renders possible remodelling and colour reintegration to be done in a single step. We softened the wax-resin mixture with the heated spatula. With the additional use of a scalpel, it was easily levelled and modelled. The missing tip of the palm branch was modelled out in this manner (Fig. 3). There was no need for additional retouching or coating. 2.2 CONSERVATION-RESTORATION TREATMENT OF THE HEAD OF CHRIST, PLASTER CAST The following two sculptures share the motif but they are made of two different materials. The Head of Christ (40 x 29.5 x 15 cm), 1933, owned by the Archdiocese of Ljubljana is a plaster cast. The most numerous among the treated sculptures by Gangl are plaster casts. Plaster is an extremely fragile and porous material, highly absorbent and easily soiled. Because of its properties and inappropriate handling and storing conditions, a plaster cast can suffer severe damage. 2.2.1 Condition before treatment When The Head of Christ was first examined, it was found to be in overall poor condition. It was broken into four pieces and it had also suffered damage from water (Fig. 4a). There were three holes on the forehead from water dripping, one reached through the entire cast (Fig. 4b). Next to the right side of Christ’s face, there was a cavity, also made by water flowing over the surface. The surface was covered with heavy deposits of dirt, dust and other pollution materials. 2.2.2 Materials and methods The conservation treatment encompassed reassembly of the broken parts, consolidation of deteriorated areas, cleaning of the surface, filling of the cracks and remodelling of the missing parts. Some of the dirt was loosely held to the surface and could be mechanically Figure 4a (upper) • Alojz Gangl, Head of Christ, plaster cast, before treatment; and 4b (bottom) • Damaged support: holes on the forehead. (© National Gallery of Slovenia, photo: M. Vuga)
102 Martina Vuga removed with a soft brush and low power vacuum cleaner. Some dirt could not be mechanically removed. The plaster was additionally cleaned by using cotton swabs damped in mixture of water and ethanol. The Paraloid B72 was used as a consolidant for the support and as a barrier coat. Procedures and materials for reattaching and filling followed the traditional plaster sculpture technology. The broken parts were glued together by means of PVAC emulsion glue [7]. Losses to the plaster were compensated using plaster of Paris (gypsum plaster), modified with the addition of animal glue to slow the setting time. Inpainting of plaster fills was finally executed after the cure by the application of Schminke watercolours (Fig. 5). 2.3 Conservation-restoration treatment of The Head of Christ, plasticine The Head of Christ (40 x 28.5 x 13 cm), 1933, from the Bela Krajina Museum (inv. no. U2) is made of plasticine (undefined synthetic modelling material coming from exploitation of petroleum products) on a wooden board. The treatment of this sculpture was more complex due to its condition prior to treatment and also due to plasticine, the material that is not very frequent in conservation-restoration practice. 2.3.1 Condition before treatment When the head was first examined prior to treatment, it was found to be in overall poor condition. It was broken into 19 pieces and fragments. Only the low part of the relief had a tight grasp onto the wooden board. A piece of plaster of Paris supported the plasticine modelling underneath in the upper part of the head (Fig. 6), while the facial part was hollow and without the support. As the plasticine with its slightly sticky character attracts and easily catches dust and other dirt from the air, the surface was covered with deposits of dirt. 2.3.2 Materials and methods Regarding the conservation treatment the first goal was to reassemble the sculpture. Several parts, e.g. the part of the eyes, did not have any sturdy plaster support, so that during the reassembling they would have begun to sag. A temporary support to these parts from the underside enabled reassembling of the sculpture. Putting all the pieces together revealed that only a few fragments were missing. There was no need to glue the parts together as they fitted nicely (Fig. 7a). Damaged areas and larger cracks were temporarily covered with a layer of Japanese paper and methylcellulose in water solution. Figure 5 • Alojz Gangl, Head of Christ, plaster cast, after treatment. (© National Gallery of Slovenia, photo: M. Vuga)
Filling and colour reintegration in a single step 103 In a complex procedure, the reassembled head was flipped and the wooden board was temporarily removed, so we could reach the sculpture from the back. The temporary support was then withdrawn. Firstly, we added some plaster at the back of the areas where the plasticine modelling was not supported, to enable later filling of the missing plasticine at the front (Fig. 7b). A small amount of the plasticine which did not contribute to the form or stability of the sculpture and represented a certain surplus was removed from the back. After the sculpture was treated at the back, the face was finally put back between the plasticine parts on the original wooden board. The patches of Japan paper were removed. The plasticine taken from the back was softened by adding white spirit and it was used to fill the missing parts and cracks on the front side of the sculpture (Fig. 8). Figure 6 • Alojz Gangl, Head of Christ, plasticine, before treatment; piece of plaster supporting the plasticine modelling (© National Gallery of Slovenia, photo: M. Vuga) Figure 7a (left) • Alojz Gangl, Head of Christ, plasticine, after reassembling, and 7b (right) • during the making of a plaster support from the backside. (© National Gallery of Slovenia, photo: M. Vuga) Figure 8 • Alojz Gangl, Head of Christ, plasticine, after treatment. (© National Gallery of Slovenia, photo: B. Salaj)
104 Martina Vuga Similarly, as in St. Agnes’s, also here the filling and the colour reintegration were done in a single step. As it was already mentioned the white spirit solubilizes the components of the plasticine. Its softness also does not permit the repeated action with cotton swabs, so the surface cleaning was limited to gentle and careful cleaning with water. Reassembling and filling were successfully applied and the sculpture regained its integrity again (Fig. 8). 3. RESULTS AND DISCUSSION The main visual component of an (achromatic) sculpture is its form. The colour of the constituent material usually determines the colour of the sculpture. The final appearance of such sculptures and the effect of the texture of the material itself, e.g. porosity of a plaster or satin look of the plasticine would be harder to achieve by retouching with a brush and a paint. So in some cases, two (final) steps of the conservation restoration treatment, the filling and the colour reintegration can be merged in one. Replacing the missing material by a (coloured) fill composed of a similar material or even using the original one can be an advantage in terms of time consume, it can be sometimes easier and with better results. In a single step procedure of filling and colour reintegration the coloured wax resin mixture was used in the case of St. Agnes. The mixture is a system without water, colour of the mixture does not change after hardening and the filling does not shrink. Applying and modelling method is very easy, working is faster. The final form, colour and shine blended well with the original surface. In terms of the achieved aesthetics, the result was very satisfactory in St. Agnes’s case. Plaster and other water-based fillings for porous materials change the colour when the water evaporates. In the case of a plaster Head of Christ, the filling and the colour reintegration in a single step would be quite difficult, as the final colour of plaster alters after cure so it is very difficult to predict it. Plaster casts can be filled with the similar materials, but they still need at least some minor retouching. Single step procedure was also used in the case of the Head of Christ made of plasticine. The original material taken from the back of the sculpture was used to fill minor missing fragments in front. With the chosen material we also avoided the problematic visual blending of the original and material added in the restoration process, which would be further complicated by the constituent material, plasticine. Single step method was successfully applied in this case too. Because we dealt with so different materials, all requirements for the reversibility of the materials and treatments were not always fulfilled. We tried to follow the principle of re-treatability, keeping the options for future treatments open, which was by far more realistic in our case. [15] 4. CONCLUSIONS In less than three years, about 40 sculptures were treated to be exhibited. The quantity of artworks, different constituent materials and the fact the treatments would need to be accomplished by the exhibition deadline were challenging. Approaches presented in this paper were inspired on some similar documented interventions, but it was quite difficult to find similar cases for the materials that are quite rare in sculpture in the first place. We also did not always apply or consider the past experience, but it is crucial to follow past and the new knowledge in the conservation-restoration field. Unfired clay objects are still a great conservation-restoration challenge. The restoration treatment of Giovanni
Filling and colour reintegration in a single step 105 Lorenzo Bernini’s Angels, preparatory models made of unfired clay have attracted my attention since the beginning in 2010 [9]. During the treatment, different materials to be used were also analysed. A specific cellulosebased impasto was developed and used for the consolidation, adhesion and structural reconstructions of unfired clay sculptures. It was not until 2016 that the Vatican Museums published a short report on the restoration treatment of Bernini’s Angels [10]. For appropriate conservation interventions on sculptures made of unfired clay in the future, we still hope for additional information on the newly developed material. Plaster objects also attract interest again and are revalued after years of having been underestimated. With the renewed interest, new studies are focused on different conservationrestoration procedures for plaster objects today. New cleaning methods have been developed [11]. There is some research work going on also on proper consolidants [12]. Dissemination of information on and for appropriate conservation interventions on different materials can improve the way conservation interventions are carried out, but in practical work, decisions are not simple and should be made in a balanced combination of knowledge, experience and ingenuity. REFERENCES [1] APPELBAUM, Barbara – Conservation treatment methodology. Oxford: Butterworth Heineman, 2007. [2] BREŠČAK, Mateja – Alojz Gangl, A Sculptor On His Way to Modernism, Ljubljana: National Gallery of Slovenia, 2010. [3] Personal communication with Satoshi Yamato, Agency for Cultural affairs, Tokyo, Japan [4] dE VRIES Bouke, The Conservation of a Vandalised Nodding Figure, Royal Pavillion, Brighton. In: ICOM Committee for Conservation, 11th triennial meeting in Edinburgh, Scotland, 1996: Preprints, London, James & James (Science Publishers), 1996, pp. 857-862. [5] VENTIKOU Metaxia, A Chinese figure in Unfired Clay: Technical Investigation and Conservation Treatment. In V & A Conservation Journal, N. 38, (2001), pp. 10-13. [6] RAVA A., BERTONE V., Problemi di restauro della terra cruda: il caso della scultura di Mastroianni alla Galleria Civica d’Arte. In: Lo Stato dell’Arte 3: III congresso nazionale IGIIC, Nardini Editore, 2006, pp. 208-15 [7] HUDOKLIN ŠIMAGA Vera, Praktična kiparska tehnologija, Navodila za vaje, Ljubljana: Akademija za likovno umetnost v Ljubljani, 1973, p56. [8] Mavec in bron v kiparstvu. In: Likovni odsevi (Kiparstvo), Ljubljana: Zveza kulturnih organizacij Slovenije,1990, pp. 106. [9] Personal communication with Fortunatina Cuozzo, conservator restorer from Vatican Museums in 2012 and Information on exhibitions. Available at: http:// www.museivaticani.va/content/museivaticani/ en/eventi-e-novita/iniziative/mostre/2016/ giovan-lorenzo-bernini-e-i-suoi-modelli.html [10] Giovan Lorenzo Bernini e I suoi Modelli, Il restauro. Available at: http://www. museivaticani.va/content/dam/museivaticani/ pdf/eventi_novita/iniziative/mostre/2016/09_ mostra_Bernini_modelli.pdf [11] ANZANI M., BERZIOLI M., CAGNA M., CAMPANI E., CASOLI A., CREMONESI P., FRATELLI M., RABBOLINI A., RIGGIARDI D. – Use of Rigid Agar Gels for Cleaning Plaster Objects. Saonata: Il Prato, 2008. [12] TISLOVA, Renata; ZITKOVA, Petra; DOUBAL, Jakub. – Consolidation treatments for gypsum plaster models. In: International Conference abstracts: Uniqueness and multiplication: plaster as an art material. Bruxelles: KIK IRPAA, EPITAAF, 2017, p.16.
ABSTRACT This paper describe the approach and challenging stages in the retouching methods and treatments of albumen and collodion photographic prints associated with a part of the collections of the Croatian State Archives, which dates from the early 19th century. Photographs where studied using microscopy analysis to assess the layers in their painted surfaces, included photographic documentation. The photographs exhibited image fading, surface scratches, tears, and cracks. They suffered serious mechanical damage - abrasions, scratches, tiny cracks overall and sometimes missing sections. The materials could not be handled without damage and conservation treatment was mandatory. The photographs were surface cleaned; stains were reduced with solvents. Damaged edges were consolidated and tears mended using Japanese paper and wheat starch paste. For the both prints was used ‘fake Baryta’ support. Retouching is made using Schmincke water colors used with RETOUCHING METHODS ON THE ALBUMEN AND COLODDION PHOTOGRAPHIC PROCESSES FROM THE CROATIAN STATE ARCHIVES Martina Bagatin Senior Paper and Photograph Conservator | Croatian State Archives – Zagreb, Croatia | [email protected]
107 1. INTRODUCTION Albumen photographic prints is a historical photographic processes that was created around 1850 (Table 1). It is a two-layer photographic process that contains paper as a base, Binder layer is present (egg white binder) without Baryta Layer; in these photographic processes paper fibers are visible through binder in highlights, and the photographs have some surface gloss (Figure 1). Main characteristics on the albumen prints are: thin paper support, high ethanol/water in different ratios. This collection represents some of the earliest published images in this region and offers a lasting contribution to our understanding of Croatian cultural heritage. Purpose of the research is to determine the different approaches to retouching methods from the different photographic processes, constant problem-solving and innovation given their fragile condition, complex structure and enormous significance. Keywords Albumen; Collodion; layers; ‘Fake Baryta’ support; Photographic material. resolution, good reproduction of fine details, deep rich brown image tone. Over time or in bad storage conditions image will fading and binder will crack. ‘The albumen print, which superseded the salted paper print in the mid-1850s, was a printout process, and here the albumen may itself act as a scavenger for the chlorine. Much later, around the turn of the century, commercial gelatin/ silver chloride printing-out papers (POP) were devised in which a halogen absorber such as citrate was deliberately added to the emulsion.’[1]. Collodion photographic prints prevalent from 1855 to about 1881. It is a three layer prints with binder and Baryta layers; paper fibers are partially or completely obscured in highlights (Table 2). Collodion prints have a warm or purple image hue; paper fibers are invisible and sometimes partially visible, no image fading, no mirroring. There are two types of collodion prints: matte collodion and glossy collodion positive sometimes with gold and platinum toning. Whether the mat or glossy depends on the amount of binder to be applied. Mat collodion have less binder while glossy collodion prints have more binder applied. Table 1 • Composition Albumen print SUPPORT BINDER IMAGE Paper Albumen Silver Table 2 • Composition of Collodion print SUPPORT PAPER COATING BINDER IMAGE Paper Baryta Collodion Silver Figure 1 • Albumen prints, cross section
108 Martina Bagatin 1.1 Deteriorations on the photographs Before selected photographs submitted to the Croatian State Archives suffered several different types of damages: mechanical and chemical damages. Mechanical damages where the secondary support was acid and brittle (prints that are mounted on acid paperboards), the surface scratched, tears, cracks and folded along the edge; Chemical damages – fading in the lightest image areas; they were severely stained from adhesive tapes and other materials. It was decided that is mandatory that the photographs must be conserved - restored before they are stored in storage space, in order to preserve the stability of photographic processes-the issue of stability and longevity. ‘This work includes an investigation of methods to restore photographs produced by historically early processes’[3]. Before any conservation treatment photographs where studied using microscopy to assess the layers in their surfaces, and includes documentation photo documentation before, during and after treatment. 2. MATERIALS AND METHODS After the detail documentation that includes the time of creation of the photographic technique, the dimensions, the historical passage, and the description of the state of the photographs, access is made to the identification of photographic techniques to confirm the process. Identification is made by visual examination to view the surface of the photographs: microscopic examination which contains analysis of elements (XRF) and organic analysis (ATRFTIR). Both examinations consist identify the chemical elements present in the layers of photographic images in order to resolve the possible doubts remaining after the visual examination. Unlike XRF analysis, the FTIR spectrometer determines the photosensitive layer (cellulose, albumin, collodion, gelatin ...) and subsequent interventions such as toning, painting or applying different coatings on the surface of the photographs. Due to identification, an adequate method of conservation, restoration and retouching of the photographs is determined. 2.1 Cleaning of the photographs and Fake Baryta support Certain measures are taken on the basis of identification and testing to increase the protection and durability of the photographic material. It was decided first to take the approach and methods in order to reduce and stabilize the resulting mechanical and chemical damages. The photographs were surface cleaned using wet and dry methods; stains were reduced with solvents, applied locally. In that case, first step was cleaning. Photographs were dry cleaned from dust, and the wet cleaning of glue residues by using the solvents (Figure 2). Soft fabrics were used and soft brushes for dry cleaning and acetone and 1: 2 ethanol and water for solvent cleaning with cotton pads. After cleaning, a starch paste and Japanese paper was used to repair the baryta layer on the paper support (Figure 3). ‘It was recognized early in the development of the photographic process that there was a relationship between the stability of the processed photographic image and that of the paper on which it was formed. For this reason, the paper used in printing photographs and the material that comes in contact with them such as mounting board, negative enclosures, interleaving paper, etc, must be of the appropriate content and quality. Photographic paper support must be as durable and stable as possible. It cannot adversely affect the silver halide emulsion coated upon it and Figure 2 • Cleaning with solvents Figure 3 • Mending, using starch paste
Retouching methods on the albumen and coloddion photographic processes from crotian state archives 109 it must be resistant physically and chemically to the chemical processing required to produce the silver image. The record obtained should keep a long time if properly processed and then stored under optimum conditions. This has been a concern of the industry from the earliest days to the present. Some knowledge of the history of photographic paper making will be helpful to the photographic conservator in caring for early and contemporary photographic artifacts.’[2] Fake Baryta layer was used for the collodion photographic process: A glossy collodion print is a three-layer print comprised of a paper support with a baryta layer, collodion binder, and a silver image. The surface finish ranges from semi-glossy to glossy due to the thick baryta layer. Baryta layer may be tinted, exhibiting an overall pink, blue, or green tint. A collodion print may also have a glazed surface, resulting in a high-gloss finish. Most glossy collodion prints exhibit a subtle iridescent effect on their surface when viewed under fluorescent lighting. Image tones range from reddishbrown to purple or violet brown. For the preparation of Fake Baryta, it was used: kaolin, barium sulphate and ‘Aquazol 200’ (Figure 4). After the preparation of the Fake baryta, approach for the retouch is made using Schmincke water colors, used with MC (metil cellulose) in water, and ethanol/water in two different rations: 1:1 and 2:1. Ethanol by its nature and composition has a tendency of drying and evaporation. The ratio of ethanol to water depends on how much it wants to achieve the speed of drying in the retouch. Sometimes due to the fragile and damaged structure of the photograph, it is necessary to quickly dry. Additionally, the composition due to ethanol helps to achieve a matte effect on certain photographic processes. 3. RESULTS AND DISCUSSION Retouching methods on the albumen and collodion photographic processes are made due to provide stability and long –term preservation. Since the surface layer of the image has faded, it had to be fixed – stabilized. The use of methyl cellulose helps to connect the final layer and image layer of the photographs, especially if there are residual toning and coating, as in some photographs. It is always essential to use compatible and reversible materials. 3.1. Retouching of the photographs After the Fake Baryta was prepared, retouch was introduced. It is not easy to achieve a certain tone, especially after the colour is dry. So it is important to do more tests, and determine the right colour. This is about monochrome colours because albumen and collodion are monochromatic. Apart from colour, it is important to achieve a matte or glossy effect, with respect to the original photographs. If missing a large part of the photography is necessary to tone the paper that is later used as filler. Approach is the same as in the original preparation of the photography: preparation of the support (paper coating and binder/ or not), and the colour is applied (Figure 5). Sometimes is really difficult to strike the right tone because photographs regardless of storage conditions tend to change colour and tone colours. ‘Conservators do not have miraculous treatments that reverse the action of time and restore photographs to their original conditions. Misguided efforts to do so can compromise the evidence of the age or the pattern of use of an object.’ [4] 4. CONCLUSIONS The main goal was to present a gradual approach to conservation Figure 4 • Preparing Fake baryta support Figure 5 • Fake baryta coat and retoruching on the albumen print
110 Martina Bagatin and restoration of photographic material, including the retouching methods as the main and final act. This is because photographs are complex as an object, always composed of several layers, and the most common cause of deterioration is factors such as poor handling and storage conditions which affect all layers [7]. This results in mechanical damage, damage to the binder (crack), and surface damage. Also, an additional problem is caused by previous nonprofessional repairs. When everything is taken into account, the retouch is part of the integral process, and the methods vary according to photographic technique. In this case, the binding layer (Fake baryta support) is the most sensitive part of the retouching, because without the proper binding layer, color and pigment stability is questionable (over time or in bad storage conditions image will fading). With all this, it is important and almost mandatory to have a good environmental conditions: temperature control and relative humidity, control of impurities and air pollution and exposure to light. Priority in preserving and protecting photographs is the first. Creating a Handbook for a photograph collection it will help a lot; fingerprints can cause chemical damage, [8] improper handling causes mechanical damage (is mandatory use of cotton gloves); allow the use of copy for various research; use of lending at exhibitions. Cool storage (below 10°C) is recommended, and colder is better unless frequently used (frequent and sudden changes in temperature and relative humidity could result in physical stress to the object). Allowable Fluctuation: ±15°C; ±5% RH [9] . REFERENCES [1] WARE, M. Mechanisms of image deterioration in early photographs. Science Museum and National Museum of Photography, Film & Television. London, UK, 1994, pp.16. [2] Eastman Kodak Company. Conservation of Photographs. Library of Congress Catalog Card No. 84-80244, 1985, pp.38-40 [3] HESS NORRIS, D., GUTIERREZ, J.J. – Issues in the Conservation of Photographs. The Getty Conservation Institute, Los Angeles, 2010, pp. 8-15 [4] LAVEDRINE, B. Photographs of the Past. The Getty Conservation Institute, Los Angeles, 2009, pp. 302 [5] COE, Brian – Color Photography: The first hundred years, 1840-1940. Ash & Grant Ltd., London. 1978. pp. 102-110. [6] Conservation of Photographs. Kodak Publication No. F-40. Rochester, NY: Eastman Kodak Company, 1985. [7] COPEDE’, M. – La carta e il suo degrado. Firenze : Nardini Editore, 2003. [8] HENDRIKS, Klaus B., KRALL, Rudiger – Fingerprints on photographs. Topics in Photographic Preservation, Volume 5. (1993), pp. 8-13. [9] UPTON, M. S. & PEARSON, C. – Disaster Planning and Emergency Treatments in Museums, Art Galleries, Libraries, Archives and Allied Institutions, Canberra. (1978)
Nome artigo 111
ABSTRACT Restoring a painting, which has already been subjected to previous conservation work, has often proved to be a challenge. According to ethical conservation principles, previous treatment is part of the artwork’s history, which should always be taken into consideration, since it reveals what happened with the painting in the past. However, improper treatment in the past can alter the readability of the painting. Trying to find the course of minimal intervention, which would sufficiently integrate previously retouched areas with the original paint layer, was one of the problems of restoring an oil painting from the Late Baroque by a Slovenian painter. The painting showed signs of support and paint damage, which were most pronounced along the edges of the painting. The unsuitable retouchings were especially prominent in these areas. During conservation-restoration treatment, the biggest concern was how to remove the discoloured and inappropriately applied materials and which techniques would pose the least further stress on the original. After the retouchings and fills were removed, numerous losses of the paint layer and canvas were found. It was important that the selected filling DEALING WITH UNSUITABLE RETOUCHINGS: THE STEPS TOWARD SUCCESSFUL REINTEGRATION Ana Oblak University of Ljubljana, Academy of Fine Arts and Design; Erjavceva cesta 23, 1000 Ljubljana-SI; E-mail address: [email protected] ^
113 1. INTRODUCTION Ecce Homo is a Baroque oil painting on canvas painted by Slovenian painter Leopold Layer. It depicts the standing figure of Jesus Christ wearing a red cloak and a crown of thorns, a motif from the Gospel of John (Fig. 1). The painting is kept in the National Gallery of Slovenia, located in Ljubljana. The painting’s unsatisfactory condition can partially be attributed to previous material was suitable for use on larger areas, allowing for a thin and layered application. Imitating the texture of the surrounding paint layer is key for integration of the fills with the original paint layer and further retouching. The condition of damaged areas and their treatment, with an emphasis on structuring the surface with fills, is discussed in this paper. At the end, practical aspects of the materials and techniques are presented and discussed. Keywords Removal of retouchings; Gamblin Conservation Colors; Filing; Texture; Retouching; Beva Gesso-P. Figure 1 • Leopold Layer, Ecce Homo, oil on canvas; 156.5 cm × 92.5 cm. National Gallery of Slovenia, Ljubljana, inv. number 514. Painting before conservation-restoration procedures.
114 Ana Oblack conservation procedures. The original linen canvas was damaged along the edges of the painting and had been lined. The painting was stretched on a wooden strainer with fixed corner joints and was mounted on the strainer with nails through the lining canvas, because the edges of the original canvas were missing. The canvas was thinly woven (7 to 10 threads per cm) and not a reliable carrier for paint layers. Lighter and darker stains were noticeable on the added canvas, which were assumed to have been caused by mould. The existing varnish was uneven and noticeably darkened. There were areas of damaged paint layer, some of which had already been filled in and retouched in the past. Scientific research revealed the sequence of paint layers and identified the majority of the pigments and adhesives used. The samples were analysed by optical microscopy, ultraviolet fluorescence microscopy, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy (RS). The original and the added materials differed in composition. 1.1. The state of retouchings Old retouchings were some of the visually most intrusive elements of the painting. They had darkened and discoloured in the ageing process. Additionally, the texture and level of the retouchings did not match the original paint layer. Added materials were frequently laid over the original paint layer (Fig 2). Some of the retouchings were applied directly to the original linen support (Fig. 3) or on the added lining canvas, and some retouched areas had an intermediate layer of filling material. Evidently the state of the materials used in previous conservation treatment was not acceptable. For this reason, removal of all the obtrusive materials and reintegration of lost paint was planned. 2. MATERIALS AND METHODS 2.1. Removal of added materials As mentioned before, the original paint layer was over-retouched in some areas. Solubility tests revealed high sensitivity of the red surfaces (mainly the red cloak). When testing the possible cleaning agents, removal of the red pigment cinnabar was detected [1]. This instability presented a major threat to the preservation of the original paint layer. These circumstances hindered our attempts to remove materials that were disturbing to the perception of the Figure 2 • Filling material and retouching applied over the original paint layer. Figure 3 • Retouching applied directly to the original linen support.
Dealing with unsuitable retouchings: the steps toward successeful reintegration 115 entire painting. Further effort was therefore required to determine the optimal course of action. The retouched areas were initially studied. The materials proved to be soluble in polar solvents, which also affected the original red paint. Considering the sensibility of the original, an attempt to reduce the polarity with the addition of a nonpolar solvent was made. To prolong the time of action of the solvent on the surface, a gelled mixture was used. This enabled us to apply solvents strictly to the desired areas. With the help of magnifying glasses softened retouchings were carefully removed with a scalpel. Residues of the gel and retouchings had to be removed with solvents in free form [2]. In most cases the areas with removed retouchings revealed a layer of fills, also applied over the paint layer. The filling material was a sturdy mixture of silicates, calcium carbonate and oily tempera. Analyses have also shown the presence of vegetable gums, waxes, starch and pigments [3]. Attempts were made to remove the filling material. Using only a mechanical approach (scalpel) was not enough due to the hardness of the material and adherence to the paint surface. The fills softened only under longer exposure to water in gelled form. Different aqueous gelled systems were tested and had a similar effect. They proved to be suitable only for areas where fills were present in thin layers on the original paint layer. Free water was avoided when removing fills from the canvas, because of the risk of shrinkage and deformations of the linen support, which could result in damage of the picture layers. Therefore further tests with heat were conducted. Using a hot air blower the fills were softened and then carefully removed with a scalpel. The goal was to safely remove as much of the filling material as possible, to reach an appropriate level for a new layer of fills. A hot air blower was also used to remove larger areas of retouchings applied directly to the canvas (Fig. 4). Compared to using solvents, this method proved to be more efficient. There was, however, a possibility of damaging the canvas when using a scalpel. Heat could also soften and damage the original paint layer. Great caution was therefore necessary when using a hot air blower and a scalpel. Figure 4 • Retouchings removed from canvas and paint layer using different methods. Figure 5 • Silicone imprint mould of the paint surface for texturing filled in areas. 2.2. Reintegration of paint losses Remains of previous conservation procedures were carefully removed, which revealed large areas of missing paint layer and damage of the canvas. Tears were mended and inlays added into the areas of missing canvas. Choosing a suitable filling material was essential. The filler had to be elastic, allowing thin application and good texturing. Imitating the original texture is key for good integration, especially in large areas of missing paint layer. Known for its good flexibility and shaping ability, Beva® Gesso-P met our demands, as it seemed particularly suitable for filling larger areas [4]. Beva® Gesso-P was applied with a spatula directly from the can. Gaps were filled in and levelled. Excessive material could easily be removed from the paint surface with low aromatic hydrocarbon solvents. An imprint mould of the paint surface texture was prepared using Zetaplus™ silicone (Fig. 5). The silicone was applied to the undamaged paint surface, pressed onto the painting with a roller and left to dry [5]. A few 2 mm thick patches were made, approximately 15 x 20 cm in size. The air bubbles
116 Ana Oblack Figure 6 • Fills, structured when dry with heat and pressure. Figure 7 • Retouching the painting: finalising with Gamblin Conservation Colors. were sometimes problematic, as they got caught between the surfaces and caused disfigurement of the imprint. The mould was marked in such a way that its correct orientation was obvious during use. The fills were textured before drying completely. The mould was pressed on to the surface and weighed down. It was removed after the fills were dry enough to be easily separated from the silicone. In cases where the imprint was not clear, the fills were textured again when dry using heat and pressure (Fig. 6). This was achieved using a heating spatula pressed on to the silicone mould. To achieve sufficient texturing the temperature had to be raised to approximately 120 °C. While the described method was effective, the silicone mould started to deform after being used for a longer time. We concluded this to be due to its susceptibility to the solvents used in Beva® Gesso-P. The solution was to simply swap the mould with another one, until the solvents evaporated and the first mould regained its original form. Using an interlayer (silicone coated polyester film) wasn’t an option due to its thickness, which prevented detailed imprinting. After reaching the paint layer level and structure, the colour reintegration followed. The base layer was done in gouache to achieve a suitable hue for the following layers. Brighter and cooler hues were used. A 10% Paraloid™ solution in acetone was applied only to the retouched areas, to prevent absorption of the first varnish layer [6]. The stretched painting was varnished with a 20% solution of Laropal® A 81[4]. The retouched areas were finalised with Gamblin Conservation Colors, mixed with ethyl lactate (Fig 7). Retouchings were built gradually in tratteggio technique. First the smaller lacunas were treated, then the larger ones. On the top section of the painting, the biggest missing segment had to be reconstructed. Larger areas of retouchings were also required on the edges, where new canvas was added. 3. RESULTS AND DISCUSSION Before starting a conservationrestoration treatment a lot of planning is usually done to ensure a smooth workflow. Nevertheless, unforeseen issues can disturb the conservation – restoration process. In our case, the sensitivity of cinnabar paint and weak, deteriorated woven fabric support were recurring issues throughout the entire conservation procedure, while trying to safely remove obtrusive elements, added in during previous conservation treatments. Several methods and materials were tested to find the most suitable course of action. While removing retouchings, great precision was required. The original red paint layer was susceptible to polar solvents in which the added materials dissolved. To soften the over-retouched areas, a mixture of polar and non-polar solvents was used. A hot air blower and a scalpel were used when removing fills and retouchings. Pemulen® gel was used for softening the fills applied to the original paint layer. Different methods were combined, depending on the area of the painting, to achieve the desired condition. Inappropriate materials were removed, as they were disturbing the painting’s visual appearance and its composition. These materials were substituted with ones we concluded
Dealing with unsuitable retouchings: the steps toward successeful reintegration 117 to be more fitting, to achieve an aesthetically suitable match. Retouching is the final stage of reintegrating paint losses. At that point a painting re-establishes its character and can be perceived as a whole. Still, colour reintegration is just one of many steps to achieving a satisfactory appearance of the filled in areas. The choice and preparation of the filling material are of great importance. Fills have to match the texture of the original paint layer, so that uniform presence is attained. In our case, satisfactory results were achieved when using a silicone mould for imprinting the texture using a hot spatula. When using higher temperatures, great caution is necessary to prevent any damage to the paint layer. For this reason, the described method is more suitable for texturing larger areas. 4. CONCLUSIONS The difficulties that were encountered when dealing with remains of previous conservation treatments were resolved by balancing preservation of the original paint layer and removal of visually obtrusive Figure 8 • The painting after conservation treatment.
118 Ana Oblack elements. As such circumstances require compromise, it is necessary to decide what interventions are acceptable in achieving a better visual appearance of the painting. Although conservators act in order to preserve original materials, in such cases they cannot overlook the aesthetic aspect of the artwork. Regardless of striving to attain minimal interventions, such practice is not realisable in some cases. REFERENCES [1] NÖLLER, Renate – Cinnabar reviewed: characterization of the red pigment and its reactions’. Studies in Conservation. Vol. 6/2 (2015), p. 79, 82. [2] CREMONESI, Paolo – An approach to cleaning and removal of film-forming materials. Ljubljana: ZVKDS RC, 12. May 2014. [3] KAVKLER, Katja, OBLAK, Ana, Leopold Layer, Ecce Homo: Poročilo naravoslovnih preiskav, Ljubljana, 2015. [4] BEVA® Gesso Description and Instructions for Use. Available at: Talas online, http://talasonline.com/photos/instructions/ Beva_gesso.pdf[accessed 2016] [5] Zetaplus, indurent gel catalyst for c-silicone. Available at: www.zhermack.com. [Accessed 2016] [6] MARQUES, Raquel, CARLYLE, Leslie - Further Developments on the Use of Beva® Gesso-P InfIlls and Solutions for Reintegration of a Large Loss. In III International Meeting on Retouching of Cultural Heritage, Postprints 2015, p. 163-172.
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Abstract The paper presents the case of coloured synthetic fillers used to reduce a number of colour retouching layers on the Baroque canvas painting St Nicholas by Fortunat Bergant (1721–1769). Temperature-sensitive lining and water-sensitive ground paint layers required different approaches to restoration technology, since the restorers in the National Gallery of Slovenia tend to use traditional hide glue fillers. Test samples were made with various synthetic materials mixed with water or other organic solvents (e.g. alcohol or acetone), with inert always being Chalk from Bologna. The selection of added pigments depended on their dimensional response and high chemical stability. Samples were observed for dimensional response, absorbency, colour, and surface finish. Tests on various synthetic fillings confirmed the statement that fillings should be USE OF COLOURED SYNTHETIC FILLERS: THE CASE OF ST NICHOLAS, A BAROQUE PAINTING BY FORTUNAT BERGANT Simona Škorja National Gallery of Slovenia, Puharjeva 9, 1000 Ljubljana, Slovenia; [email protected]
1. INTRODUCTION Fortunat Bergant, a painter of traditional Baroque technology, applied paint layers on a coloured ground with extensive underpainting in cold or warm tones. The paint layer consists of several layers superimposed one upon the other in a manner to achieve Keywords Coloured filling, Acrylic dispersion, Inpainting, Water-and-temperature-sensitive layer, Baroque painting the most complex colour effects. The colour effect is brought about by an optically subtractive mixture of thin layers of paint (applied in contrasting tones as a rule). Within the paint surface the thickness and number of paint layers vary. The painting has a slightly granulated surface. Initial probes on the painting showed that the original reddishorange ground was highly sensitive to water. Furthermore, in the past the painting had been lined with a starchresin mixture which does not allow the use of thermoplastic fillers. The stated facts were the reason why different synthetic polymer fillers were prepared and tested in the studio. Commercially manufactured fillers were not subject of testing as chosen according to specific damages in the paint layer. Since synthetic fillers are not as malleable as traditional hide glue ones, various restoration materials could be used on a single work of art. Coloured fillings can already imitate the colours of the underpainting and consequently reduce the number of colour retouching layers. Therefore, the procedure also reduces water intake when gouache or watercolours are used for inpainting. Figure 1 • Different types of losses they are recognized to be problematic. [1] 1.1 Types of losses on the Bergant painting The painting had suffered from different types of damages, including layer separation. Severe losses, when both the paint and ground layers were missing, were most extensive. Those missing parts had been infilled in the past by hide glue-chalk fillers. The old fillers whose structure or level were not suitable were removed (about 60% of filled surface). In some parts of the background only colour layer separation could be observed (only upper layers of the paint layer were missing). Those shallow damages had been retouched in the past with thick oil paint. A darkened oil retouch which had also had the function of filling was removed. It was necessary to find such a filler whose single application (extremely thin missing layer) would also reproduce the surface texture of the original paint layer.
122 Simona Škorja Old fillers which were not completely removed also needed further treatment – additional filling in different level relations. Those that were preserved were adapted through mechanical treatment to integrate into the original surface. 1.2 Coloured fillings In view of the painter’s subtractive manner of applying a paint layer, it seemed reasonable to use coloured fillers. This sort of practice is also known from 19th-century technological manuals. [2] Within the Slovenian context, such practice is related to wax-resin fillers that were mainly used in restoration in the second half of the previous century. In the process of filling the painting of St. Nicholas the idea was to come close only to the colours of the underpainting or to reproduce mainly the information it contains: the value of the light-dark contrast, the value of the cold-warm contrast. The aim was not to completely recreate the quality of colour of the underpainting (or even the final application of paint), but to leave the surface sufficiently “open” (lightness and coldness of a hue) for the application of one or two layers of the final inpaiting. A very important issue to be considered is dimensional response and chemical stability of added pigments. We definitely have to avoid adding hygroscopic pigments, especially earth pigments containing clay, such as Umbras, Siennas, Ochres, etc. and particularly Van Dycke Brown, Natural Iron Oxide and Veronese Green. [3] In the process of adding pigments to a filler, Laura Fuster-López calls attention to Critical Pigment Volume Concentration; the following equation can be used: PVC % = ( V pigment / ( V pigment + V binder)) X 100 If too much pigment is added it can affect mechanical properties of a filler: it decreases stiffness and strength, and on the other hand it increases flexibility. The surplus of pigments also results in lower dimensional response: fillers become weak and fragile and tend to crack, and consequently to fall out. [3] 1.3 Isolation of the filler After filling has been completed, an isolation layer should be applied. The isolation layer creates the boundary between the filler and the layers that follow. [4] The function of the isolation is to prevent absorption of the binder from inpainting and to saturate the porous surface (as pre-preparation for the final varnishing) in the sense of achieving, as much as possible, uniform absorbency all over the surface. 2. MATERIALS AND METHODS 2.1 Tested fillers The advantage of some selected synthetic materials is that they are soluble in and miscible also with polar organic solvents (i.e. acetone, alcohol), not only in water. On the market they are available as water dispersions or solids (Aquazol®). The composition of acrylic dispersions is not known in all details; undefined types of acrylates, bulking agents, ammonia or ammoniated compounds can be present as well as pigments, preservatives, emulsifying and foaming agents, etc. On the other hand, the solid linear polyamide Aquazol® is of known composition, with no additional ingredients. [5] All selected synthetic materials for fillers can be worked out with polar organic solvents (i.e. acetone, alcohol), thus levelling, texturing and removing excess material, even though they were applied as acrylic water dispersion. It is advisable that all synthetic fillers be applied in a thin layer on a previously dried up layer. The major disadvantage is shrinkage caused by evaporation of water or solvents. Shrinkage ranges from a few percent up to 50%, therefore the use of structural support is required in the
Use of coloured synthetic fillers: the case of St Nicholas, a baroque painting by Fortunat Bergant 123 case of larger-scale damages. But as noted in literature, evaporation cracks can be filled with no effect on the final strength and bond of the filler. [6] Air bubbles are another disadvantage of synthetic fillers, especially acrylics; they can occur during the application and/or drying of the filler and they create an unsuitable, unwanted texture of the surface. Practical use and laboratory tests of acrylic fillers have also shown their considerable limitations related to environmental changes of temperature and relative humidity. [3] For this reason the use of acrylic fillers should be limited only to those works of art which are exhibited in controlled conditions. In our studio practical observation tests were made for the following types of fillers: one sample of traditional hide glue filler, three samples of acrylic fillers prepared with water, and two samples prepared with acetone or ethanol, one of them being linear polyamide. All materials were prepared as 10% solution, with the addition of varied amounts of Chalk of Bologna, Samson Kamnik as an inner [7], except for the hide glue that was prepared in 7% solution, serving as a reference for its handling properties. It is preferable to prepare fillers that Table 1 • tested fillers; recipes and photos of samples in daylight and raking light SAMPLE/ RECIPE DAYLIGHT RAKING LIGHT sample 1: 7 g rabbit glue, soaked for 24 h 100 ml water 200 g Chalk of Bologna sample 2: 10 ml Ares 33 10 ml water 30 g Chalk of Bologna sample 3: 10 ml Plextol® D 498, Deffner&Johann’s 10 ml water 20 g Chalk of Bologna sample 4: 10 ml Acrylic Emulsion D 498-M Lascaux 10 ml water 20 g Chalk of Bologna sample 5: 10 ml Acrylic Emulsion D 498-M Lascaux 10 ml acetone 20 g Chalk of Bologna sample 6: 10 ml of 10% solution Aquazol® 500 in ethanol 5 g Chalk of Bologna
124 Simona Škorja are fluid enough for brush application in thin layers. Application with a brush renders possible extraordinary precision as to where and how much of the filler is applied (it allows control over the thickness of application). In contrast to hide glue fillers, more time is available for corrections because their drying time is longer. With precise application we can avoid the problem of clouding which often occurs when surplus filler is removed with a cotton pad soaked in a solvent. Two layers of the filler were applied to sample models with a brush, after the first layer was already dry. The Lascaux’s Acrylic Emulsion D 498-M mixed with acetone is an exception; it may become too dense to be applied easily with a brush (sample 5). Sample 1: traditionally prepared hide glue filler (as reference) which has excellent working properties, stability and reversibility [8]. In our case it requires too much water intake while it is applied and levelled. Sample 2: Ares 33, Samson Kamnik (working properties similar to Primal AC 33, Kremer pigmente as it was available on the market about 10 years ago) requires more inner than other acrylic dispersions, but it is still within the safe range. The inner is miscible well enough with the binder, although some minor air bubbles can appear during application in a thick layer. It dries quite quickly, certain losses of volume can be observed comparing to hide glue filler. Sample 3: the Deffner&Johann’s Plextol® D 498 has very good mixing properties, but many air bubbles appear which remain on the surface also after drying (undesirable texture). While still wet, it seems like a hide glue filler, but after drying significant loss of volume is observed. Furthermore, it can be too elastic to be levelled off with a blunt scalpel. Sample 4: the aqueous mixture of Lascaux’s Acrylic Emulsion D 498-M has the best cohesion of all tested acrylic fillers, but some additional tests should be done. It has a minimal amount of bubbles when still wet, but they disappear after drying. It dries slowly, again a significant loss of volume can be noticed. Sample 5: the acetone mixture of Lascaux’s Acrylic Emulsion D 498- M becomes denser than aqueous solution, therefore it is more easily applied with a spatula. The dried surface becomes rougher than in the case of the aqueous mixture, but it can be worked out while the filler is still semi-wet. Sample 6: Aquazol® 500, Kremer pigmente was prepared as 10% solution in ethanol. The advantage of this material is that is soluble in a wide range of solvents, including water. The Aquazol® 500 has the highest viscosity of all the tested acrylics, very similar to hide glue fillers. It requires a really small amount of inner, only 5 g, if we want to apply it with a brush. However, the Aquazol® , suggested as a substitute for hide glue fillers, does not have equally good working properties, also a certain loss of volume can be observed. 2.2 Pigments for colouring the fillers To colour the fillers two mixtures of pigments were prepared; a cold one and a warm one. All selected pigments were (pre)wetted in ethanol a day before the use for achieving better mixing properties. The added amount of pigments was always below 0.4 g. The “cold pigment selection” was prepared for the background of the painting. A mixture of synthetic Ultramarin dark and Vine black (ratio ca 1:1) was added to the Ares 33 filler (sample 2) and the Aquazol® 500 (sample 6). The “warm pigment selection” was prepared for other parts. The following pigments were added to the Lascaux’s Acrylic Emulsion D 498-M (sample 5) prepared with acetone: synthetic Iron Oxide, Vine black and Ultramarin dark.
Use of coloured synthetic fillers: the case of St Nicholas, a baroque painting by Fortunat Bergant 125 The ratios of the pigments were decided by test mixing and drying of coloured fillers. The process was repeated several times in the case of “warm pigment selection” before the desired colour hue was achieved. 2.3 Tested isolation materials Two 10% solutions of different materials were used for testing isolation of the filler: organic shellac in ethanol (traditional use) and the synthetic Paraloid B-72 in the mixture of solvents of acetone and ethanol (ratio 1:1). Both solutions were applied in two layers on all samples of fillers which, however, were not coloured. It should be taken into account that the addition of pigments may change the porosity and absorbency of the surface. Simple droplet tests of porosity were made, measuring the time of droplet penetration on the isolated layer of the filler. The samples were photographed every 30 seconds for 40 minutes and observed. As expected, the shellac solution provides a better isolation layer than the Paraloid B-72 for all samples. The most hygroscopic fillers are the ones made with organic solvents, with the Aquazol® 500 standing out. It demands substantial isolation before inpainting. 3. RESULTS AND DISCUSSION For the process of filling the painting in question, three different types of acrylic fillers were used after careful consideration: Ares 33 (sample 2), Acrylic Emulsion D 498-M (sample 5), and Aquazol® 500 (sample 6). The fillers were coloured in accordance with the local tone of underpainting (warm-cold and black-reddish), depending on the area on which they were applied. Most of the fillers were applied with a brush in several layers. Application with the brush enabled the imitation of the granular structure of the original colour layer. Thanks to precise application there was no need for subsequent working on the fillers. Figure 2 • Tested isolation materials on filler samples, UVF Figure 3 • Detail of the filling and inpainting process; losses (1), filling with a brush (2), levelling with blunt scalpel (3), isolation, one layer of guache inpainting (4), mimetic, aquarelle inpainting made of one or two layers with (5)
126 Simona Škorja Minor corrections were necessary at the contact of the filled surface and the original colour layer. The surplus of the filler was removed with a blunt scalpel. For the thinnest damages of paint layer the Ares 33 (sample 2), coloured with a cold tone, was used. The filler renders possible the application in extremely thin layers, with no air bubbles occurrence. Brushstrokes enabled the recreation of the appearance and texture of the preserved original layer. Poorer mixing of the inner with the binder was an advantage in our case, since this “fault” perfectly recreated the granular surface of the original paint layer. The use of a filler mixed with water did not seem problematic for it was not applied directly on the support but on the lower layers of the original paint. This filler also proved to be excellent for complementary modelling of old fillings where their level had been too shallow or where they had been applied imprecisely. The filler Lascaux’s Acrylic Emulsion D 498-M, mixed with acetone (sample 5), was applied either with a brush in the case of minor and shallow damages (in this case minimal amount of acetone was added to facilitate the application) or with a spatula in the case of deeper damages. Application with a spatula does not allow such a high degree of precision as the application with a brush does. In this case the surplus amount of the filler was removed with acetone. Most of the surplus filler was removed when it was only semi-dry, which diminishes the possibility of clouding. Another advantage of coloured fillers is in the fact that the latter phenomenon is not as pronounced and disruptive as in the case of white fillers. Figure 4 • Drawing of the used fillers; Aquazol® 500 (sample 6), Ares 33 (sample 2), Lascaux’s D 498 M acetone (sample 5), white colour old, existing fillers.
Use of coloured synthetic fillers: the case of St Nicholas, a baroque painting by Fortunat Bergant 127 The deepest damages to the support and the paint layer were filled with the Aquazol® 500 in several layers. Because structural support was not used, minimal cracks occurred, even though the filler was applied in thin layers. All fillings were isolated with a 20% solution of shellac, in the case of the Ares 33 two layers sufficed. In the areas of fillings with the Lascaux’s Acrylic Emulsion D 498-M (sample 5) three layers of isolation were necessary here and there. With the Aquazol® 500 filler, the isolation was applied in five layers at the least. Final colour integration was made with one layer of gouache colours, followed by individual emphases in watercolours, in the sense of mimetic inpainting. 4. CONCLUSIONS The use of synthetic fillers in the works of art that are sensitive to moisture and temperature is a good alternative because they enable the preparation, treatment, and possible removal of fillers in polar solvents which differ from water. Because of their properties which change with ageing it is advisable that the works of art are stored in controlled conditions. I would particularly like to point up working properties of acrylic filler Ares 33 which can be applied in extremely thin layers, thinner than in the case of traditional hide glue fillers. The advantage of colouring the fillers is that we can re-establish the formal unity of the painting, thus the structural level as well as the aesthetic level, almost in a single step. A coloured filler requires minimal inpainting (three layers at the most), which also means that we introduce minimal amount of material which is sensitive to light. With the imitation of the colour of the underpainting the execution of the final inpainting is less demanding both in terms of the material and aesthetics. The time of the inpainting execution is considerably shortened, which saves time and, consequently, reduces the costs of the conservation-restoration intervention. A special feature of the present case study lies in the fact that the choice of the filler was dictated by the type of damages to the painting. According to available information from industrial producers (Material Safety Data Sheet), material composition of individual acrylic fillers is rather similar, yet unknown in details to the users. From this standpoint, it was reasonable to make good use of the positive working, dimensional and mechanical properties of individual fillers for individual types of damages. When using acrylic materials, we have to keep in mind, like with all commercial products, that the composition is trade secret and can be changed without notice. Therefore, in the case of a new packaging, we always have to make previous tests to check whether the material has preserved equal working properties before we use it on a work of art. In any case, a regular, continuous use of acrylic fillers, like all other synthetics suitable for fillers, requires further investigation, so careful consideration of their use on an individual work of art is always necessary.
128 Simona Škorja REFERENCES [1] FUSTER LÓPEZ, Laura – Filling. In HILL STONER, Joyce; RUSHFIELD, Rebecca, ed. – The Conservation of Easel Paintings. New York: Routledge 2012, pp. 586-606. [2] FUSTER LÓPEZ, Laura; CASTELL AGUSTÍ, María; GUEROLA BLAY, Vicente, ed. - El Estuco en la restauración de pintura sobre lienzo. Criterios, materiales y procesos. Valencia: Univ. Politécnica de Valencia, 2008. [3] FUSTER LÓPEZ, Laura; Loss compensation in paintings: Filling, 11th Masterclass, Casa-Atelier Vieira da Silva, Lisboa, 2016. [4] KNUT, Nicolaus, The restoration of paintings, Cologne: Könemann 1998, pp. 253. [5] DE LUCA, Daphne, BORGIOLI, Leonardo, SABATINI, Luigia, VITI, Valentina- Manufatti dipinti su support tessile, Reintegrazione delle lacune, Proposta di materiali alternative, Kermes, Anno xxv-Numero 88 (OttobreDicembre 2012), pp. 42-54. [6] JAIC online; LOEW CRAFT, Meg; A. SOLZ, Julie-Commercial viniyl and acyrlic fill materials. Available at: http://cool.conservation-us.org/ jaic/articles/jaic37-01-003.html (3 March 2017). [7] The composition of Chalk of Bologna, Samson Kamnik: 59 % calcium carbonate, 37,8 % gypsum, 2,4 % anhydride, 0,7 % flint, 0,1% dolomite. The results were obtained by XRF-ThermoFisher Scientific, Niton XL3t 900S-He. The measurements were made by dr. Matej Dolenec, Natural Science Faculty, University of Ljubljana, november 2017. [8] HUDOKLIN, Radoje; Tehnologija materialov, ki se uporabljajo v slikarstvu, njihova priprava, obdelava in uporaba, prvi del. Ljubljana: ALU, 1955, pp.161-206.
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Abstract The objective of this paper is to present a workflow procedure to support the graphic recording of the operations performed during the retouching process involved in paintings. In this particular context, an orthophotography of a portrait painted on canvas from a university museum collection was used in Blender, a free and open-source 3D creation software suite. Blender uses an important metric coordination value, provided by the 3D workspace software that allows the areal characterization and numeric identification of each surface loss. The step-by-step procedure adopted to document and map lacunae in this artwork for subsequent retouching, is described. MAPPING LACUNAE FOR RETOUCHING PAINTINGS WITH COMPUTER GRAPHICS SOFTWARE Frederico Henriques (1, 2, 3) | Ana Bailão (1,2) | Rui Bordalo (3) | Agnès Le Gac (4) | Alexandre Gonçalves (5) | Liliana Cardeira (2) | Eduarda Vieira (1) | António Candeias (3) 1 Universidade Católica Portuguesa/ Escolas das Artes/ CITAR; Rua Diogo Botelho, 1327, 4169-005 Porto; [email protected]; [email protected] 2 Faculdade de Belas Artes da Universidade de Lisboa/ CIEBA; Largo da Academia Nacional de Belas Artes, 14, 1200-005 Lisboa; [email protected]; [email protected]; 3 Universidade de Évora/ Laboratório HERCULES; Largo Marquês de Marialva, 8, Palácio do Vimioso, 7000-089 Évora; [email protected]; [email protected] 4 Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia, Departamento de Conservação e Restauro & Laboratório de Instrumentação, Engenharia Biomédica e Física da Radiação, Campus da Caparica, 2829-516 Caparica; [email protected] 5 Instituto Superior Técnico/ CERIS; Av. Rovisco Pais, 1049-001 Lisboa; [email protected]
1. INTRODUCTION In conservation and restoration documenting all the actions executed on artworks through a graphic recording is essential. The same applies in paintings regarding the exact location of the operations carried out on the pictorial surface. In the condition report, the tear areas, traces of abrasion, overpaints, fillers, cleaning spot tests, areas of sampling (e.g. cross sections) and analysis spots (Raman, XRF, colorimetry, FORS, among others), for example, should be recorded [1]. The registration of paint losses is also one of the tasks that should be performed [2]. For the digital registration of losses, several computer programs can be used to register either vector (e.g. AutoCAD, Adobe Illustrator, Inkscape, etc.) or raster (e.g. Photoshop, Gimp, etc.) archives. However, a coordinate system is necessary for mapping. Concerning the available types of digital documentation, several nonconventional applications, such as Keywords Documentation; Graphic recording; Retouching; Painting; Ortho-image; Blender. geographical information systems (GIS), have enormous potential and can be used in the field of Conservation [3][4][5]. The aim of this work, based on the portrait of Professor António Vicente Ferreira (figure 1) painted by Álvaro Perdigão in 1944 [6], is to present the workflow procedure to support the graphic recording of some operations in conservation and restoration, in particular during the retouching phases. The painting belongs to the Museum of Civil Engineering, of the Department of Civil Engineering, Architecture and Georesources of Instituto Superior Técnico, in Lisbon. The method begins with a photogrammetric process [7] to acquire an ortho-image of the painting. In a second phase the work is fully performed with Blender, the chosen 3D modelling software. The vector graphic operation occurs prior to the conservation treatment. Blender is an open-source and free software and an all-in-one tool with useful capabilities for documenting cultural heritage. It is a multi-purpose computer program in the areas of 3D modelling, rendering, simulation, video editing, game creation, infographics schemes, scientific illustrations, virtual environments, exporting to several formats (including vector and 3D printing files), and animations, among other capabilities [8]. 1.1 Orthophotography or orthoimagery Ortho-images are well-known in geographic mapping representations. An ortho-image is a digital dataset and can be used in geographic information systems as a layer to support the Figure 1 • Photograph of the portrait of Professor António Vicente Ferreira with a calibration chart.
132 Frederico Henriques | Ana Bailão | Rui Bordalo | Agnès Le Gac | Alexandre Gonçalves | Liliana Cardeira | Eduarda Vieira | António Candeias creation of other data. They are essential for producing maps of the Earth’s surface, such as city maps, that require the correction of the image geometry and scale. Such images have uniform scales, correction of the inclination perspective and the effects of parallaxes produced by the optical equipment. Acquiring and producing an ortho-image is critical to measure true distances in surfaces and mapping the events on the space. According to principles advanced in panel paintings [9], the same system was applied in the present casestudy to the pictorial surface. The ortho-image was obtained using a photogrammetric method, which consists of making measurements from photographs (multiple records). 1.1 Mapping lacunae with Blender Mapping lacunae in paintings should always be done with vectorial drawings. Some graphic maps, frequently in usage in Conservation and Restoration or in technical studies, are made with raster drawings, with Photoshop® or similar software. However, such scope is limited. To obtain a current and regular recording of the pictorial layers and surface, it is better to create a vectorial record because it allows the interoperability of the data between software. Just like other 3D software, Blender has the ability to create solids, planes (polygons), points, etc. The workflow presented in this paper started with polygons under the image of the pictorial surface (ortho-image). Blender can also be applied to substantiate technical and analytical studies of Cultural Heritage assets. In this case study, Fiber Optics Reflectance Spectra (FORS) (figure 2) was used. This equipment obtains the spectral information on a given spot of the painting concerning its reflectance properties in the 300 to 1000 nm range. In Blender, 12 points of FORS readings were mapped on the surface layer, registering their positions and values. 2. METHODS The method was applied in two main steps: the first with photogrammetric procedures to obtain a plane model of the artwork and the second with vectorial drawing to build up features related with the lacunae. 2.1 Orthophotography To produce the ortho-image, a software named Agisoft Photoscan® [10] was used. This photogrammetric software is widely used to produce 3D models and also to acquire terrain information with unmanned aerial vehicles (UAV). The photogrammetric software works with the upload of a set of photographs acquired in sequence Figure 2 • During the characterization of colour and spectral acquisition with FORS. Figure 3 • Screenshot of the photogrammetric project in Agisoft Photoscan® software with the photographs taken in mosaic grid.
Mapping lacunae for retouching paintings. With computer graphics software 133 around the painting or in strip lines. To obtain good results it is necessary to apply the best practices in photography. In this project, a tripod, two light sources with softboxes to provide diffuse light, and a DSRL camera NIKON D3200 (24 MP) equipped with a CMOS sensor and a lens AF-S NIKKOR 18-55 mm were used. All the images were obtained with the same value of focal length (23 mm), low ISO value (100) and aperture (F/8). The resolution of the photographs is 6016x4000 pixels, approximately 12 MB, and was saved in JPG file format. The vibration reduction (VR) of the lens was in switch off mode. In this museum project, the photographs acquisition was similar to what would be used for aerial photogrammetry, scanning the surface in strip lines, with a high overlapping of photographs, between 60% and 70%. The set of records (57 positions) is an aggregate of organized images in a mosaic (figure 3). After processing the data, the result obtained was a 3D model. On this basis, one of the functions of the software to generate an ortho-image could be used. Two types of images in orthophotographic view of the painting were acquired: the first in low resolution, in JPF file format (8057x9416 pixels) with 11.4 MB, and the second in high resolution, in TIFF file format with 345 MB. For the next phase of the project, with Blender software, the JPG file was sufficient to map the lacunae. 2.2 Mapping the lacunae with Blender software The mapping process with the 3D modelling software Blender (v. 2.78) began with the upload of the orthoimage in the project. Then, the object was oriented in X, Y, Z axes, and the map scale was updated to display proper distances at the centimetre scale. If the option consists in uploading the 3D model produced by the photogrammetric software, it is necessary to import the OBJ file format and respective texture (JPG file format). This sort of procedure is very useful to create virtual scenarios (figure 4), to produce infographics schemes or to make animation movies. However, in the current project on mapping losses, only the JPG image and 2D file as a plane were needed. The drawing of several gaps was made in “edit mode” extruding points around the lacunae area; this resulted in a polygon defined by segments and nodes (figure 5). Then, it was necessary to make a polygon with all points. The new element consisted in one object with a unique ID (characterized as loss unit). All drawn losses could then be organized in groups or in one group with a hierarchy and organization system. The cartography was made after the manual work of editing all polygons (losses). The final output was not Figure 4 • Render image produced with Blender software that simulates a virtual gallery. Figure 5 • Screenshot of Blender workspace during the editing process.
Figure 7 • During color retouching with “texture painting” clone tool. 134 Frederico Henriques | Ana Bailão | Rui Bordalo | Agnès Le Gac | Alexandre Gonçalves | Liliana Cardeira | Eduarda Vieira | António Candeias only a map of losses, but also a map of original and non-original paint. Moreover, such a cartography resulted also in a map of risk displaying the most vulnerable areas of the painting (figure 6). 3. RESULTS AND DISCUSSION This workflow with an ortho-image, generated with a photogrammetric software, and vectorial editing of lacunae with a computer graphics software allowed to accurately identify all gaps in the painting. Each lacuna, after the manual drawing, acquired an identification number to match a lacunae unit. The total number of lacunae in this painting is 22 and there are14 regions with abrasion. Besides a straightforward localization of the gaps on the whole surface, according to the adopted color scheme (lacunae of red color over a plane grey ground), the cartographic map also allowed to Figure 6 • Cartographic map of lacunae and vulnerability areas of the pictorial surface. quantify the percentage of losses, which amounts to 1.9%. By guaranteeing an automatic calculation, Blender as a tool proves also essential because it allows an objective, reliable, reproducible, and extremely fast and friendly quantitative assessment. This type of evaluation is central to both diagnosis and intervention because it provides a secure expertise as to the degree of authenticity of the artwork; it establishes precisely the defective chromatic areas, their shape and distribution; it contributes to the cost estimation involved in the inpainting process, be it digital or real in the work itself. Another possibility that Blender offers is, in fact, the virtual retouching. This kind of operation is widely applied with photo-editing software, with 2D images. It can also be made directly in the 3D model, in the imported photogrammetric object or even in the 2D image. The operation is made with the well-known clone tool (figure 7). It is worth emphasizing the added value of digital color retouching, for its absolute reversibility and its benefit as an independent and didactic support that, together with the real painting, can promote its better understanding (figure 7and 8). After generating a cartographic recording of lacunae, each 3D project can always be adjusted or consolidated with more data. This is fundamental to understand the scope of 3D projects in Cultural Heritage and of the Conservation and Restoration technical studies. As an example, an online 3D model for virtual visualization was also produced in this project. The virtual platform Skecthfab® was used to this end [11]. The platform hosts a 3D repository and a collection of some 3D museum objects. The analyzed painting is one of them, thereby becoming a powerful public awareness medium regarding Cultural Heritage concerns [12] (figure 9).
Figure 8 • Main region of the painting after the color retouching process (left side) and “UV map” and respective texture of the 3D object (photogrammetric model) (right side). Mapping lacunae for retouching paintings. With computer graphics software 135 Figure 9 • An overview of 3D model painting useful for on-line visualisation in the Sketchfab® platform and repository of museum objects. Figure 10 •Virtual scenario made with Blender. The image informs about the location of analysis spots with FORS system. It is also necessary to refer the large potential of virtual scenarios and infographic strategies with 3D modelling techniques. The tool can also be used to communicate in Heritage Documentation, using 3D modelling techniques of the industry of films and games. This means that the documentation techniques and procedures in Cultural Heritage meet effectively the computer graphics knowledge area. Here, a simple presentation of a virtual scenario was made with the mapping of analysis spots (FORS) on the museum painting (figure 10). 4. CONCLUSIONS The use of current computer graphics (CG) tools in Cultural Heritage is starting to get attention from the community of conservation and restoration professionals. It is important to refer that CG software is not a substitute for GIS or CAD systems, but a possibility to promote infographic illustrations, like those of cartographic products, for threedimensional objects. About the GIS software and CG software available nowadays, it is possible to work with standard files and export files to ensure the interoperability within project data. In the future, with the massive amount of information acquired in conservation-restoration operations, it is critical to create comprehensive databases for the data associated with each artwork, enabling the storage of all information from conditioning reports, conservation and restoration interventions, laboratory and analytical reports, as well as the graphical documentation produced for the object. Noteworthy is also the potential of graphical documentation to produce and register spatial analysis and risk maps of the artworks.
136 Frederico Henriques | Ana Bailão | Rui Bordalo | Agnès Le Gac | Alexandre Gonçalves | Liliana Cardeira | Eduarda Vieira | António Candeias REFERENCES [1] STUART, Barbara H. - Analytical Techniques in Materials Conservation. Wiley, 2007. [2] SCHMID, Werner - Graphic Documentation Systems in Mural Paintings Conservation (GRADOC) Roma: ICCROM, 2000. [3] FUENTES PORTO, Alba - Los Sistemas de Información Geográfica aplicados al estudio de las superficies pictóricas. Valencia: Universidad Politécnica de Valencia. Dissertação de Mestrado, 2010. [4] HENRIQUES, Frederico - Metodologias de Documentação e Análise Espacial em Conservação de Pintura. Porto: Universidade Católica Portuguesa, 2012. PhD thesis. [5] BAILÃO, Ana; HENRIQUES, Frederico; MENDES, Susana; GONÇALVES, Alexandre - Estudo para a caracterização espacial e bidimensional das lacunas no processo de reintegração cromática da pintura “A Circuncisão do Menino Jesus”. Ge-Conservación. 10 (2016), pp. 6-19. [6] PAMPLONA, Fernando – Álvaro Perdigão. In Dicionário de Pintores e Escultores Portugueses. Barcelos: Livraria Civilização Editora, 2000, Volume IV, p. 288. [7] HISTORIC ENGLAND – Photogrametric Applications for Cultural Heritage. Guidance for Good Practice. Swindon: Historic England, 2017. [8] Blender. Home of the Blender Project. Available at: https://www.blender.org/ [31 January 2017]. [9] BAILÃO, Ana; HENRIQUES, Frederico; CABRAL, Madalena; GONÇALVES, Alexandre – Primeiros passos de maturidade a caminho da reintegração cromática diferenciada em pintura de cavalete em Portugal. Ge-Conservación. 1 (2010), pp. 127-141. [10] Agisoft Photoscan. Available at: http://www.agisoft.com/[30 November 2017] [11] Sketchfab. Publish, share, and discover 3D content on web, mobile, AR, and VR. Available at: https://sketchfab.com/[30 November 2017] [12] The 3D model of Engineer António Vicente Ferreira painting (Sketchfab). Availlable at: https://sketchfab.com/models/b5e53dde93 454b8cb88ae0b64c195e2b [30 November 2017] ACKNOWLEDGEMENTS We are grateful to the Museum of Civil Engineering, of the Department of Civil Engineering, Architecture and Georesources of Instituto Superior Técnico, in Lisbon, for providing access to the painting used in this study and also to its Director, Prof. Ana Tomé (PhD Arch). This project had the financial support of Fundação para a Ciência e a Tecnologia (FCT) through a Post-Doctoral Fellowship (SFRH/BPD/99163/2013).
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ABSTRACT The Italian Institute for the Conservation and Restoration (ISCR) carried out a conservative intervention on some marble high reliefs and statues from the Cathedral of Orte near Rome. Some pieces have extended polychromy and gilding, some have a few traces, and some have none. Our goal was how to balance those differences and also how to harmonize the original areas with the already repainted and regilded ones we decided to keep. For a correct methodology we took inspiration from recent treatments adopted in ISCR on different materials as terracotta and wood sculptures and greek and roman pottery. GOLD AND POLYCHROMY ON STONE: A PROPOSAL OF RETOUCHING METHODOLOGY THAT CAN APPLY ON ALL TRIDIMENSIONAL ARTWORKS S. Pannuzi(1) | M. Valenzuela(2) | D. Montemaggiori(3) | G. Galanti(4) 1 Archaeology, MIBACT-ISCR; 2 Restorer, MIBACT-ISCR; 3 Restorer, dariamonti libero.it; 4 Restorer, giorgiagalanti gmail.com
1. INTRODUCTION Last year, we carried out a conservative intervention on some marble high reliefs and statues from the Cathedral of Orte, near Rome [1]. These artworks were part of the altar dossal of the Saint Valery Chapel, built during the first years of the sixteenth century [2] with marbles, reused probably from the Antiquity, belonging to two different altars [3]. In the second half of the sixteenth century this dossal was moved from a chapel to the main altar in the cathedral presbytery. In the eighteenth century the altar dossal was dismembered, and each part had then a different reuse with new polychrome covering [4]. Now most of the pieces are shown at the Diocesan Museum of Orte. In the original phase, when exhibited in the chapel, the altar was painted and partially gilded. When moved to the main altar it was fully and extensively re-gilded. Presently due to the different conservation conditions some pieces have extended polychromies and Keywords Colour reintegration, Gold reintegration, Tridimensional Works of art, Polychrome sculpture, Attic vases, Retouching techniques. gilding, some have only a few traces, and some have none. If the altar could one day be rebuilt at the end of our intervention, our aim will be to balance those differences. We started working on three sculptures that show some extended areas of beautiful and well-preserved gilding with some evident losses. Decision had to be taken: reintegrate or not the gold? Which materials to use, pure gold, micas, bare watercolours? Which technique to choose: an identifiable or a mimetic one? Which alternatives ways we had? This contribution will illustrate different methodological and technical proposals about retouching. 2. MATERIALS AND METHODS The examined stratigraphic samples [5] show a first original layer with gold leaf on decorative reliefs, smalt blue and azurite on flat grounds, and a second gilding layer coinciding with the underlying one. The altar was then extensively regilded (third layer of gold) when moved from the chapel to the presbytery of the cathedral, in the second half of the sixteenth century. We also found, dating of nineteenth century, a layer of Prussian blue and artificial ultramarine blue, layered on bare areas of the reliefs. Our cleaning intervention didn’t remove any colour at all and any gold layer, even if some of them were identified as non-original. We decided to keep the more recent and extended gold layer, because it has an important historical weight, as well as the traces of different non-original blues which give us an idea, although pale, of what probably the altar was like. We thought that retouching the gold losses on stone polychromies should not be too different from retouching similar losses on other materials. For a correct methodology we took inspiration from first treatments adopted in ISCR on bi-dimensional panel paintings [6,7] using the tratteggio technique. The same methodology as been used recently on tridimensional gilded and/or painted artworks as cold painted terracotta sculptures [8], wood sculptures [9] and greek and roman vases. Being the use of tratteggio unsatisfactorily applied on tridimensional objects, quite recently
140 S. Pannuzi | M. Valenzuela | D. Montemaggiori | G. Galanti in ISCR we are trying to unify the technique of recognizable retouching on all kind of tridimensional objects, applying colours not with the tratteggio but with the puntinato. This technique was first introduced at ISCR in the restoration of wooden polychrome sculpture in the early ’90, following the methodology so well illustrated by Paolo and Laura Mora with Paul Philippot [10] for wall paintings. Examples of puntinato: 1.The terracotta Nativity, by Saturnino Gatti (Sixteen century), Santa Maria del Ponte, L’Aquila. Composed of three elements modelled and cold painted, damaged by the earthquake of 2009. The lacunas in the gold mantels were in the past retouched as losses of the ground, with the colour of the bolo layer [11] applied in a mimetic way (see Fig.1). After cleaning and removing the old retouchings and fillings we decided to reintegrate the gold losses. We first filled the losses with a gesso ground, and then we covered the surface with a coating of even, uniform gold mica based watercolour (Schminke). When dried we applied watercolours with the puntinato method in order to catch the perfect tone and make recognizable the area that had been reintegrated (see Fig.2). 2. The Apulean Amphoras, from the National Archaeological Museum of Naples. These objects had no gold colours, but they are interesting to testimony the possibility to reintegrate limited losses by modelling and drawing what can surely be reconstructed in a way which can be easily identified, using the same puntinato technique (see Figure 3). “The result is a reconstruction which is invisible at the normal viewing distance but easily recognizable at close range” [10]. These words, used to describe the tratteggio technique, perfectly explain the puntinato. RESULTS AND DISCUSSION Presently we had been working only on three elements of the altar, and we will be working very soon on the other four pieces: it’s only considering all the pieces together that we will be able to verify the options about the aesthetic issues and the final presentation. Basically, we had to deal with two colours, the pale fade blue and the shiny compact gold areas. We did a very light retouching in the blue area, using Figure 1 • Nativity by Saturnino Gatti (Sixteen century) Santa Maria del Ponte (L’Aquila), a detail of St. Joseph, terracotta and cold painting. A: Losses of the paint layer previously retouched imitating the red bole (before); B: Same losses with gold retouching, watercolours and mica (after). Figure 2 • Detail of fig.1. A: lacuna retouched imitating the red bole; B: same lacuna with gold retouching, detail of the puntinato.
Gold and polychromy on stone: a proposal of retouching methodology that can apply on all tridimensional artworks 141 light watercolours glazes to provide the uniformity to the surface that showed wears of patina and colour. The gold, very well preserved, had to be retouched to reconstruct the losses. In the past at the IsCR, losses of gold leaf had first been retouched with bare watercolours which could not match the shine of gold. Shell gold was then introduced and applied on watercolours base with the tratteggio technique. But the result was still dull because the vertical lines come out heavy and thick. We tried then to apply the gold leaf first, with the guazzo technique, and execute the tratteggio with watercolours on top: the effect was finally very satisfying. Similarly, applying a layer of uniform, even mica gold colour and using on top the watercolours to execute the tratteggio or the puntinato was also working well with the advantage of being far less expensive. In our case study we did reintegration in tiny areas of the gold leaf with Scminke aquarelle mica gold but treated differently larger lacunas. At the beginning we decided not to reintegrate the larger areas. The disturbing visual interferences on the surface of the bare stone, appearing through the losses, were treated with glaze watercolours to re-establish the uniformity of the surface, receding in space. Progressively, we reached the decision to reintegrate the gold losses in the Saint Leonard robe because they are in a very prominent position, and because of their extension, not too vast. There was no need of a ground because the layer of the original gold leaf around the lacunas Figure 3 • Naples, National Archaeological Museum, Apulian Amphora. A: reconstruction shape; B: after puntinato retouching. was very thin. We put directly on the surface of the stone a coating of mica gold. The perfect matching of the colour was reached using watercolours that were applied with the puntinato technique on top of the gold coating, in order to make them be recognizable at close range. It is premature to assert which will be the final solution for the retouching that will be adopted. We made and used drawings in order to develop some hypothesis of the ancient polycromy, based on the traces of the original layers we founded. We documented the different phases and the many changes the coloured areas had during the time. This restitution was
142 S. Pannuzi | M. Valenzuela | D. Montemaggiori | G. Galanti intended to help the study of the sculptures. Possibly if the altar will not be reconstructed in the Museum, we suggest realizing a small copy of the monument using 3D printer with the reconstruction of the polychromies based on the most assured hypothesis we made. That will help the fruition of the sculptures. CONCLUSION This specific case gave us the opportunity to check on polychrome marble sculptures a retouching methodology that can be the same for all the tridimensional art crafts and can easily be applied. REFERENCE [1] ANSELMI, Salvatore Enrico Sculture lapidee e lignee. In ANSELMI, Salvatore Enrico; PRINCIPI Lorenzo ed. Il museo d arte sacra di Orte. Perugia: Nuova Linotypia 2000, 2013, pp.50 53 [2] LEONCINI, Lando La Fabrica d Orta Orte manuscript XVII century [3] NEGRI ARNOLDI, Francesco I marmi quattrocenteschi del Museo Diocesano di Orte. In MADDALO, Silvia ed. Tesori di Orte. Manziana (RM) :Vecchierelli Editore, 1998, pp.73 85. [4] A nameless drawing dated 1723 shows all these marbles on the main altar before its destruction ANSELMI, Salvatore Enrico Commitenze ad Orte in età barocca. Cultura gesuita e influenza pozziana. Gli Alberti e I Nuzzi. Roma: Argos, 2006, pp.126 131 [5] Results will be soon published in Bollettino ICR Roma [6] MORA, Costanza; PROVINCIALI, Beatrice; SOAVI, Albertina - Antonello nel percorso delle opere restaurate dall’Istituto Centrale per il Restauro: dall’Ecce Homo del collegio Alberoni alle tavole degli Uffizi, in Kermes Dossier 19 (aprile / giugno 2006), Firenze: Nardini 2006, pp. 50-66 [7] AA.VV., BASILE, Giuseppe, GRECO Vera ed. -Annunciazione Antonello da Messina: il restauro. Palermo: Regione siciliana, 2008. [8] HUBER, Helisabeth; PRUNAS, Maria Elisabetta; VALENZUELA, Marisol; CATALLI, Emiliano; PASTORELLI, Monica; RAIMONDI, Elena; Tecniche di esecuzione e intervento di restauro, in MIRACOLA, Patrizia, ed. Il restauro di due opere in terracotta dipinta il presepe di santa Maria del Ponte e la Madonna di Collemaggio. Roma: Gangemi Editore, 2015, pp. 21-42 [9] VALENZUELA, Marisol; CONTI, Laura; TOCCI, Laura; L’intervento di restauro sulla scultura lignea policroma del XIII sec. Madonna con Bambino conservata presso la Pinacoteca civica di Fabriano: problemi di presentazione estetica, in GIUBBINI, Giovanna ed. -150 anni della Pinacoteca di Fabriano. Milano: Affinità Elettive, 2014, pp. 95-106 [10] MORA, Paolo e Laura, PHILIPPOT Paul Problems of presentation, treatment of losses in Conservation of wall paintings. London: Butterworths 1984, pp.304 306. [11] Bolo is the ground (Armenian bole, usually orange reddish colored) used to apply the gold leaf (guazzo technique). It’s clay component makes possible to burnish it.
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ABSTRACT In the restoration of wooden sculpture, the application of a new gilding traditionally appeared as the best option to handle the problem of wear damage and gaps in a gilded surface. This practice, which continues up to this day, however, rarely reproduces the quality and technique of the original: colour of gold, colour of the mordant, water or oil gilding, matt or burnished surface, presence of glaze… Alternatives were found in the use of metal powder such as bronze powder, which oxidizes rapidly, and a wide range of micas to reproduce the glittering metallic surface in different colours. Alternative options that do not imply the use of metallic powder are favoured by the authors. Following the concept of a ‘relative gap’ in sculpture formulated by Paul Philippot (1970) [1], the different case studies presented in this paper illustrate that to “THE GOLDEN STAIN OF TIME”: THE INPAINTING OF GILDINGS ON WOODEN SCULPTURE Emmanuelle Mercier | Erika Benati Rabelo Institut Royal du Patrimoine Artistique. Parc du Cinquantenaire 1, B-1000 Bruxelles [email protected], erika.rabeloé@kikirpa.be
1. INTRODUCTION Dealing with the subject of reintegration of losses on gilded surfaces on polychrome wooden sculpture requires to first define the terms of the title. First of all, what value do losses on a wooden sculpture represent? In 1970, Paul Philippot distinguished between an absolute lacuna on a 2D image and a relative lacuna on a 3D object. He explained that “… contrary to what happens in a painting, the colour of the polychromy should not depict the object but rather qualify be appreciated, a gilding on a wooden sculpture doesn’t necessarily have to be complete. When inpainting is needed, the use of pigments in various mediums makes it possible to carry out surface colour harmonization and allows to perfectly reconstruct the optical continuity of the gilded volume ensuring the distinctness and reversibility of the intervention. Keywords Sculpture; Gilding; Inpainting; Loss compensation; Reversibility; Distinctness the volume already provided by the sculpture”[1] . In other words, contrary to an easel or a mural painting, the polychromy represents or mimics above all a material, a texture and less often, figurative depictions. This difference significantly influences the viewer’s perception and acceptance of a damaged object. Secondly: what role does gilding play in a polychromy? What value is attributed to it? As a metallic leaf applied on top of a layer of bolus, can we distinguish it from the pictorial layer which contains the artist’s stamp, his brushstroke? When it is deteriorated by the passing of time, can we simply replace it without betraying the authenticity of the work of art? Or on the contrary, should we respect its material authenticity? Despite the existence of international ethical guidelines, our criteria for the decision making rest upon socio-cultural values, to which we should add the restorer’s personal experience, his training and his influences. By means of concrete examples, we will see how in practice the different degrees of acceptance of losses and the values accorded to gilding lead to a wide range of solutions and a multitude of retouching techniques. 1.1 When the object was completely regilded Since the Middle Age, polychrome wooden sculptures were entirely repainted and regilded when they were damaged, or simply to bring them up to date. In Belgium, this tradition continued without interruption till the end of the nineteenth century. During the period of the neogothic movement, the restoration aimed at returning the object to a hypothetical pristine state which implies reproducing the gleam of the gold. The intervention makes the sculpture look like it had just come out of the artist’s workshop. However, already at this time, the secretary of the Royal Commission for Monuments, Jean-Baptiste Rousseau (1829- 1891), complained about the habit of stripping altarpieces to repaint and regild, describing the practice as barbarous [2]. This pioneer wished
146 Emmanuelle Mercier | Erika Benati Rabelo for restorers to apply the principle of “the less you do, the better” (1873). Nowadays, even if the practice is not quite extinct, it is at least not approved by the public authorities. However, the following question is still posed to us, restorers, many times: “And are you going to regild or repaint it?” Indeed, the general public does not entirely understand the difference between the treatment reserved nowadays for sculptures and for historical interiors. In the 1990s, some rooms in the royal palace of Brussels were studied prior to their restoration. The study revealed the high quality of the original gilding, and in particular rich variations in the tonality of the gold leaf [3]. These subtle contrasts were then reproduced with the same techniques by a team of professional gilders under the supervision of restorers. Even today, in the restoration of historical interiors, the application of a new gilding appears to be the best option to tackle the problem of wear damage and losses on gilded decorative elements. In France, a chemical marker has been developed by the firm Dauvet in partnership with C2RMF to ensure the traceability of gold leaf used within the field of restoration [4]. This practice, however, rarely reproduces the quality and the technique of the original. In the framework of certain restoration sites, when gilding on mordant – which works easier and faster – is applied to an ensemble without bearing this “sfumature” in mind, the result is often exceedingly heavy, indeed kitsch [5]. In the past, partial gilding was also used to cover losses on sculptures. During the restoration of the Opitter altarpiece in 1875, the restorer did not entirely repaint and regild the retable as was usually done, but simply regilded the losses imitating the painted decorative motives and the sgraffito on gold of the original polychromy. This kind of treatment was applied to the Kerevot altarpiece in France during a highly interventionist restoration in the 1970s. This intervention is clearly visible but not particularly harmonious. Alternatives were also found in the use of metal bronze powder, which oxidizes rapidly. It is often a real challenge for conservators to eliminate this material without damaging the gilding underneath. In 1983, it took a villager two hours to apply a bronze powder on the garment of the Virgin in the Church of St. Bavo in Erpe-Mere (13th century). It took us two years to eliminate it mechanically and make the underlying gilding visible again. 1.2 Minimal intervention At the IRPA, when treating losses, we do not differentiate between gilded and painted areas – the polychromy is a unity of both. Contrary to the previous examples, we attempt to tone down the visibility of the damaged area and improve comprehension of the sculpture, while emphasizing its historical value. This implies accepting the wear and losses on the gilded surfaces of sculptures and altarpieces and to treat them with the same criteria that are applied to the pictorial layer in compliance with ethical guidelines, including discernability, removability, etc. As a very general rule, the degree of acceptance of a gap by the general public is proportional to the age of the object. Hence the importance of justifying our choices and explaining the reasons behind the degree of intervention (or non-intervention). We are well aware that this approach is not adopted everywhere. In the decision making process, the choice of both the degree of intervention and the retouching technique involve distinguishing the different types of losses encountered: the wear of the gilded surface; loss of the metal leaf revealing the mordant, the bolus, the white preparation, or the bare wood; loss revealing the
“The golden stain of time”: the inpainting of gildings on wooden sculpture 147 juxtaposition of different surfaces, etc… The following examples will be classified depending on these different kinds of degradation. 1.2.1 Lacunae with visible wood surrounded by gilding The Virgin from Marche-les-Dames (TreMa Museum in Namur, ca. 1260) illustrates a kind of treatment usually adopted at the IRPA, and which consists of leaving the bare wood visible in the lacunae. It is presumed that viewers are able to mentally reconstruct the missing part. In order to help them in this task, it is sometimes necessary to give the wooden surface a more homogeneous appearance. The altarpiece of Bouvignes (ca.1555) treated in 1992 is another example of this option (fig 01 and 02). The bare wood is clearly distinguishable from the remains of polychromy. It can be compared to a neutral tone with the advantage however of being an inherent element of the sculpture, an intrinsic part of it. From an aesthetical point of view, the tonality of the wood is similar to that of the gilded parts, especially as the wood is oak. In the end, this kind of minimalist intervention enables the reconstruction of the optical continuity of the sculpture’s volume while integrating the gilded areas still present (fig 01 and 02) 1. 2. 2 Lacunae with visible wormeaten wood surrounded by gilding A Dormition of the Virgin (1501- 1550) from the Moranzone workshop in Italy (Museum of Fine Arts, Gent) suffered damage from wood-boring insects, producing numerous gaps. The treatment carried out did not involve any retouching [6]. In fact, the filling in of carefully selected insect galleries and holes, helped to regain a certain structural continuity of the reliefs and shift attention away from damages. The intervention consisted first in making the back panel look more homogeneous and flat in order to function as a background again. Secondly, fillings made it possible to re-establish a certain fluidity in the lines of the architectural elements. The choice of the gaps to be filled in, often depends on the conservator’s own sensibility. Therefore, it is important to determine beforehand those losses that are most disturbing to the perception of the form and the composition, in order to make our intervention as logical and justified as possible. Sketches and digital simulations were made as a support for the discussion during the decision making process which was carried out collegially. Fig 01 • The altarpiece of Bouvignes 1555 (ca), after treatment Fig 02 • The altarpiece of Bouvignes 1555 (ca), after treatment.
148 Emmanuelle Mercier | Erika Benati Rabelo 1.2.3 Juxtaposition of losses revealing the bare wood and losses revealing the white preparation surrounded by gilding. When losses revealing the bare wood show a little white chalk or gesso ground, it is often sufficient to tone down the white preparation in order to move these areas into the background. It corresponds to what S. Bergeon considered as minimal reintegration which, according to her, consists of “… treating the visual emergence of areas that are too bright or irregularities in the support, the preparation, or the coating in order to move these areas into the background …”[7]. This is usually achieved by retouching these white remains or spots to match the tone of the wood in order to restore the structural continuity of the volume. In the case of the Virgin from La Gleize (13th century - Museum Grand Curtius, Liège), losses with exposed bare wood are integrated as explained before and thus left visible, whereas in the more extensive lacunae revealing the white preparation, the retouching mimics the gilding by applying overlapping glazes. To ensure reversibility of the inpainting, the choice of retouching materials and solvents has to take the nature of the gilding (water or oil-based) and its sensitivity into consideration. We should, however, avoid multiplying retouching options on the same object at the risk of seriously disturbing the viewer’s perception of both the form and gilded surface. 1.2.4 Losses revealing the bare wood and losses revealing the white preparation surrounded by red bolus A Saint Jacob (ca. 1350) from the church of Sainte-Waudru, Mons, was treated in 1998. The gold leaf was severely deteriorated, revealing large areas of preparation with remains of red bolus. Here, one could state that the deteriorated gilding, deprived of its shiny effects, acquires a statute similar to a pictorial layer. The retouching was carried out by applying small dots of a reddish colour close to each other in order to distinguish the retouching from the remains of bolus. 1. 4 Retouching on fillings Even though in general we advise to leave lacunae that reveal the bare wood visible, in practice certain losses may be judged to be disturbing, for example because of their geometric shape. Other losses can interrupt the fluidity of a drapery or even be interpreted as an iconographic element that is foreign to the work of art. The reasons for applying fillings to gaps could be exclusively based on conservation ethics. For instance, deep gaps in relief areas where there is a risk of scraping off the gilding during handling, or gaps that could also become “dirt holes”. Definitely secondary in the context of a museum, aesthetic criteria become important for religious sculptures that are still objects of devotion. The fillings are usually flat in order to make the reintegration appear brighter and match the smooth and glittering metallic surface of the gilding. Once the mastic is applied, restorers have various options for retouching. The Virgin with Child called “Causa Nostrae Laetitiae” in the Basilica of Tongres (15th c.) is still an important object of devotion. The procession that occur every 7 years is considered a great event in Belgium. The sculpture was the object of a restoration treatment in the early 1990s. Fillings were applied to the top of the outstanding folds. Conservators chose to mimic the worn areas revealing the bolus, which was applied with large brushstrokes. This intervention it is well-documented with photographs and easily reversible. It is nevertheless difficult to distinguish the original gilding from the retouching. This is due to the perfect mimetic result of the intervention. This phenomenon has been underlined by the Italian architect Camillo Boito in “Conserving
“The golden stain of time”: the inpainting of gildings on wooden sculpture 149 or restoring, the dilemmas of heritage” (1893), where poor restorations let him distinguish between the old and the new, whereas good restorations plunge him into such perplexity of judgement that the pleasure of contemplating the monument vanishes [8]. When it appears necessary to fill a lacuna for conservative or aesthetic reasons, retouching with tiny dots or ‘pointillism’ is the method that is nowadays generally applied at IRPA as illustrated by the treatment of a Virgin known as Our Lady of St. Séverin in the St.-Martin Church in Liège (ca. 1520) in 2000 (fig 03 and 04). This miraculous Virgin and Child is still a popular subject of devotion in Liège. As in the previous example, the salient parts showed many losses revealing the underlying wood. The worshippers seem to have made it a practice to strip off the gilding and take the fragments with them, possibly because they ascribed magic properties to them, as being relics. For reasons of conservation, but also in the hope of putting a stop to this practice, it was decided to fill in these lacunae. A pointillist retouching with pure colours was carried out on the fillings and on the zones revealing the white preparation in the worn parts of the gilding. In the areas where the gold was still in good condition, the retouching was carried out in the same tone. In the zones that were worn due to the manipulations of the statue, such as dressing it or walking it in the procession, and showed the red bolus, the tone was adapted to the bolus. This was done to conserve the traces of the material history that are linked to the sculpture’s cult (procession and dressing of the sculpture). The materials used for retouching differ from the sculpture’s original materials to assure reversibility. The degree of gloss is determined by the binder and its concentration. The vibrant effect of this type of retouching compensates the absence of the metallic reflections of the gold leaf. In our opinion, in most cases, the addition of mica highlights is not necessary. We avoid it as much as possible. The pointillist technique is part of the large family of ‘stylised repetitive retouching’ alongside with the tratteggio or the “selezione effetto oro“, or the “interpolation“ or “camouflage“ used in Denmark since 1990 [9]. When applied to 3D objects, the advantage of the pointillist retouching seems to be that it doesn’t enter into competition with the form, which is sometimes the case with retouching with parallel hatching. This is due to the fact that the dots form a neutral motif as they are not arranged in a certain direction such as a line (no top or bottom, nor sides). Indeed, on a painting the lines of retouching are applied vertically while in the case of a sculpture’s polychromy, the restorer would be inclined to adapt the direction of the lines to the modelling of the reliefs, such as drapery folds. This is indeed what Ornella Casatta suggested: “il tratteggio avrà un andamento che dovrà tenere conto dei valori plastici del originale” [10]. Interpreting the relief (3D) through the retouching (2D) introduces an element of tension and ambiguity. While the original gilding characterized the material of the relief (for example a drapery fold), the retouching is laid over the form as if it rebuilt it. This leads to a distortion that provokes a conflict in the perception of the relations between retouching and form on the one hand, and retouching and gilding on the other. It goes without saying that, with every type of visible reintegration, the final effect largely depends on the skills of the restorer. Some retouching have the tendency to visually step forward, accentuating the lacunae at the expense of the original gilding, which moves back. This phenomenon happens even in the case of the famous retouching of the Santo Vescovo, 14th c. in the Bargello museum in Florence, which can be considered as a milestone for the history of restoration. Indeed,
150 Emmanuelle Mercier | Erika Benati Rabelo this sculpture has acquired a historical value. We can also cite retouching on the Christ by Cimabue, which has acquired a double value: a historical one for the development of the ‘astrazione chromatica’ by Ornella Casazza and Umberto Baldini, and a commemorative value referring to the incident that profoundly marked the city of Florence: the flood of 1966. In some cases, however, the pointillist technique does not appear as the optimal solution. This case can be illustrated by the frame of the altarpiece of St. Denis. The lacuna had a geometrical shape and was situated in the middle of the frame. In this case small mica (minerals from different silicates) highlights were added to restore the metallic effect and to better harmonize the retouching. Finetec® provides a wide range of micas to reproduce the glittering metallic surface in different colours. 1. 4 Decorative patterns with/on gold What happens when gilding is part of decorative patterns? During two conservation campaigns of the altarpiece of Our Lady, known as the Saluces altarpiece, in 1973 and 1988, it was decided beforehand to not carry out a chromatic reintegration but to leave the wood exposed in the losses even in the parts that are decorated with rich applied brocades. A different approach was chosen for the treatment, in 2003, of the Virgin (ca. 1440) in the church of St. Nicolas, in Drogenbos, which raised the question of the reconstruction (recognizable or not) of the motifs in the losses. The protruding parts of the garment folds again had deep losses that showed the bare wood and fragments of white and orange grounds. In this case, after filling, we only carried out a pointillist retouching in the gold colour of the background without reconstructing the motifs. This solution enabled to avoid the use of a hypothesis to replace the missing patterns of the polychromy and at the same time, it has allowed us to reconstruct the continuity of the volume and of the material: gold. All in all, it is as if we had artificially moved the deep gap to an upper level that is estimated more acceptable or at least less disturbing. CONCLUSION Depending on the nature and on the function of the gilded sculptures or ensembles, the variety of solutions Fig 03 and 04 • Our Lady of St. Séverin (ca.1520) in St. Martin Church (Liège) after treatment. Fig 05 and 06 • Virgin (ca.1440), in the church of St-Nicolas (Drogenbos), after treatment.