LAUNDRY TESTS UNDER SCIENTIFIC CONTROL SHOW HOW TO PREVENT ...

LIVING STANDARDS ON THE FARM 569

LAUNDRY TESTS UNDER SCIENTIFIC CONTROL SHOW

HOW TO PREVENT DAMAGE

The average household has a considerable investment in its bed
linen, table linen, and other fabrics that must be laundered. There-
fore anything that can reduce or offset the wear and tear of the laim-
dering process is an important home economy. The Bureau of Home
Economics is conducting a series of tests and studies with different
sheetings which have been manufactured from known grades of raw
cotton under supervision of the Bureaii of Agricultural Economics.

An obvious aim in such a project would be the prevention of scorch.
It is easy to recognize damage by scorch when the iron has been hot
enough to cause a stain. There m ay have been just enough heat, how-
ever, to cause a tendering of the fabric which is quite invisible. If this

FIGURE 218.—Household ironer with which fabrics can be ironed at a known temperature and pressure

occurs often, the fabric soon wears out. The experimental work thus far
has developed a method of measuring the degree of scorch, as follows :

Before any fabric is ironed, the manufacturer's sizing or dressing is
removed by the use of enzymes and a light washing process. Break-
ing-strength tests show that this treatment does not materially
alter the mechanical properties of the cloth. All samples to be ironed
are conditioned in a controlled humidity room, in which a relative
humidity of 65 per cent is maintained. The moisture content of rep-
resentative samples can then be carefully determined.

While the fabrics are being passed through the experimental ironer
shown in the illustration (fig. 218), the temperature of the heated me-
tallic shoe is obtained by an electrical device, in which the thermo-
couple replaces the ordinary mercury thermometer. The cloth being
ironed is in contact with the heated metal under known pressure for
about two and one-half seconds. The factors of time and pressure are

570 YEARBOOK OF AGRICULTURE, 1932

not varying here as in hand ironing, where they depend upon the oper-
ator. Uniform pressure conditions in the ironer can be maintained,
however, only by careful attention to the contact between the metal
shoe and the revolving roll. The latter takes the place of the board in
hand ironing, and must be kept uniformly well padded.

The material used at present on the experimental ironer consists of
two layers of regular knit cotton padding, two layers of napped, double-
faced cotton felt, and a muslin cover. In actual service, only muslin
which has been preshrunk can be used satisfactorily on account of the
moisture absorption from the fabrics being ironed. The preshrunk
knit cotton padding offered to the laundry trade would doubtless give

an additional advantage.

Scorched Covers Should Be Changed

The covers need to be changed as soon as they develop even a slight

indication of scorch. Fabrics ironed on scorched covers are liable to

acquire yellow stains

in the presence of

moisture and the oxi-

dized or burned cotton

material. This is ob-

vious in the yellow col-

oration taken on by

hot water in which a

moderately scorched

cover has been allowed

to stand for a short

time. Any padding

used with such cover-

ing should be well

aired, as it has usually

acquired anodorwhich

is soon communicated

to a fresh cover and to

the materials that are

FIGURE 219.—Cotton-sheeting material treated with méthylène blue being ironed. The
solution, magnified SO times: A, Scorched material; B, unscorched padding o f the ironer
material should be unrolled and

fluffed up frequently to avoid any hard packing often occurring after

continued service. While the roll should be uniformly firm, it should

yield somewhat to the different materials that are being laundered.

In this connection it should be noted that no one fabric will be ab-

solutely uniform throughout in thickness or surface. This becomes

more evident from the manner in which scorch effects have appeared on

the fabric shown in the magnified illustration. (Fig. 219.) It will be

apparent that in the case of a light scorch the fibers on the surface act

as a protection to the yarns underneath. When they constitute the

only scorched part of the fabric, the breaking strength of the cloth is

not noticeably changed. This is particularly evident in heavy, thick

sheetings ironed under low pressure at a comparatively high temper-

ature.
The yarns illustrated in Figure 220 were taken from other parts of

the fabrics shown in Figure 219. In order to make the scorched con-

dition more visible, the fabrics were treated with a solution of méthyl-

ène blue dye. The comparative resistance of the unscorched fabric to

LIVING STANDARDS ON THE FARM 571

this treatment may be seen in Figure 219, B. This fact is made use of,
but with a different procedure, in a quantitative method of estimating
chemical damage in the ironed cloth.

The weakening of the fibers taken from a scorched yarn is well illus-
trated in Figure 221. Both the unscorched fiber and the scorched were
treated with the same chemical solution (Fleming and Thaysen solution).
The comparative degradation of the scorched fiber is plainly evident.

In this study of ironed fabrics various methods are being used for
detecting chemical change. The viscosity determination is one of the
most satisfactory of
these methods. In this
test the ironed sample
is ground and dissolved
in a cuprammonium
solution. The time
rate of flow of this cot-
ton solution in an ac-
curately measured,
fine tube is then ob-
tained. The more ten-
dered the cloth sample,
the more rapid will be
the flow of the solution
through the tube.

Color Measurements
of Surface Changes

When the mechani-

cal and the chemical

damage appear very

slight, color measure-

ments are employed

to detect certain sur-

face changes. À

scorched condition is

indicated by the small-

er amount of violet

lightreflected from the

sample. By a modi-

fied spectrophotomet-

ric method, determina- FifiURE 220.—Cotton yarns from sheeting material wiiich have been
tions of the light re- treated with méthylène blue solution: A, Scorched yarn; B, un-
scorched yarn
flected from the cloth

are made for definite regions in the red, in the yellow, in the green,

in the blue, and in the violet. While a deep scorch will obviously

lessen the total amount of light reflected from a fabric, a faint scorch

in a sample wiU be evident mainly from the smaller amount of blue-

violet light reflected.

Observations made on the ironer when it is set for a pressure of from

1 to 1% pounds to the square inch, show changes in certain 4-ounce

sheetings for temperatures as low as 473° F. The surface of the roll

just before it touches the hot metal is then at a temperature of from

99°_to 104° (slightly warm to the hand). If the roll is allowed to turn

against the heated surface so that its surface temperature is slightly

572 YEARBOOK OF AGRICULTURE, 1932
more than doubled, these same sheetings may be affected at a temper-
ature about 45° lower. The first measurement described with the
cooler roll is doubtless more comparable with hand ironing. It is of
interest to note here that under service conditions for a period of time,

FIGURE 221.—Cotton fibers treated with Fleming and Tliaysen's solution, magnified 640 times:
A, Scorched fiber; B, unscorched fiber

the washing procedure appears to influence the scorching temperature
of a fabric. Further investigation in this field should yield consider-
able information of practical value.

K. MELVINA DOWNEY, Bureau oj Home Economics,