This section is from the book "Clothing And Health. An Elementary Textbook Of Home Making", by Helen Kinne. Also available from Amazon: Clothing And Health.
Miss James and the girls of Pleasant Valley tried some simple tests for materials. Perhaps you would like to try them too ?
The Pleasant Valley girls became so interested in Miss Travers' talk about textiles and how difficult it is to buy intelligently that they decided to learn to judge materials and to study about adulterations.
How are clothing materials adulterated? Miss James told the girls that there are a number of ways of adulterating materials, and that most women shoppers are so indifferent that manufacturers have been able to adulterate the materials of everyday use. This increases the cost of living, for materials do not wear so long. Miss James says that textiles should be labeled so we may know what we are buying. Some kind of adulterations are honest if the goods are so marked ; but, when sold for something they are not, the buyers are fooled. The tests help one to know whether materials are adulterated or not. Let us learn first some of the methods generally used in adulterating, and then some of the simple tests.
Weighting is one method of adulterating. This means that something else has been used beside the material. In cotton and linen material, sizing or starch is pressed in with the rolling in finishing. After washing, this material will be found to be very open in mesh instead of smooth. Notice some of the smooth linen table cloths before they are laundered. Afterwards you will notice they look quite coarse and have lost their smoothness. Sometimes glue or clay or gums are used instead of starch.
Silk is often weighted in the finishing process with sugar and some with dyes and metals. This is because silk has a property which enables it to absorb a great deal of moisture without changing its quality. The manufacturer can buy salts and dyes for less than silk, and so he often uses a large per cent of dye or metal in place of the gum washed out of the silk in manufacture. One can seldom find to-day silks like our grandmothers used to use. This is because people wish cheap silks; the manufacturer cannot produce silks for little money, as the raw fiber is so high; and so he uses other things with silk to weight it.
Materials are also adulterated by combination with other materials. Did you ever buy a handkerchief marked "pure linen" and discover it was a mixture of cotton and linen? Cotton is also used to adulterate woolen materials, and sometimes silk materials; "pure silk" so called, is often artificial silk.
Adulteration is also practiced when made-over materials or waste is used to cheapen the cost. We learned about this in studying about wool. Wool materials should be labeled so that the purchaser will know. It is not fair to pay the price for an all-new wool material if shoddy and mungo and flocks, which are all old wool and waste, have been used. The per cent of new wool should be told and the price made accordingly.
Fig. 143. - One can sometimes test materials by burning.
Silk is sometimes sold as reeled silk when waste from cocoons which is called spun silk has been used for the woof or filling thread.
In finishing of materials, adulteration is sometimes practiced. In pressing cotton or linen, a luster is given to the surface. Cotton can be made to appear like silk or like linen, and is often sold for those fibers. Cotton can be napped in finishing and made to look woolly as in blankets or outing flannel, but it is still only cotton.
How can clothing material be tested?
These are the simple tests which the Pleasant Valley girls learned:
For sizing. This is easy to identify. Pick at the surface with your nail, and the starch or sizing will easily come off. Hang a wet piece in the air and see how the gloss looks then. This sizing often conceals defects in the cloth.
Fig 144. - The microscope reveals many things.
Fig. 145. - The test for fading.
These can be seen if the material is thin, by holding it against the light.
Burning tests. The girls unraveled the fibers which Miss James gave them and tested wool, silk, cotton, and linen. They tried both warp and filling threads. They burned them with a taper. The animal threads (which are they?) burned slowly, charred, and smelled like burned feathers. Silk burns to an ash, except when weighted. Then it burns more slowly. When very heavily weighted, the flame does not burn readily and the form of the silk will remain. The vegetable fibers, cotton and linen, burn quickly and with a flame.
Tests with microscope. You have all seen the appearance of the fibers under the microscope. This reveals many things, and the unraveled fibers are easily identified. The microscope is the only sure test for telling cotton and linen fibers. One can sometimes discover shoddy mixed with the all-wool fiber because of the color. Shoddy is sometimes made of old colored woolen rags.
Fig. 146. - The test for shrinkage.
Tests for fading. Pin a piece of cloth on a board with thumb tacks. Cover half with cardboard or heavy paper. Expose to the rays of sun for several days. Remove paper and notice difference. A piece can also be exposed near bright light, but not in sun's rays, to see the effect under ordinary wear. Marjorie Allen tested a piece of cashmere she was considering for a dress and decided not to buy it, for it faded quickly near the bright light.
Tests for strength. Try to break either warp or woof threads. Place the two thumbs together and press down on the cloth which should be held firmly in the hands. Try both sets of threads. Sometimes a weak warp or woof can be discovered.
Tests for shrinkage. Barbara Oakes had a white cotton dress last year which never seemed to stop shrinking. Sometimes we can test materials for shrinkage. Measure width and length of sample to be tested. Wash it in hot water and soap. Dry and measure again. Is it narrower and shorter? In planning for cotton or woolen garments allowance should be made for shrinkage.
Fig. 147. - The test for strength.
Chemical tests. Chemicals are used for identifying fibers. Have you learned in your eighth grade studies about acids and alkalies? Have you studied at all about chemicals? It is possible to discover the composition of woven materials by testing them with chemicals. This is because acids and alkalies affect vegetable and animal fibers in different ways. Look up the difference between acids and alkalies. Study with your teacher and try to discover some of the common food and cleaning materials which we use every day in our homes which are acid or alkali. Some of these teach us we should know what the soaps and washing powders which we use will do to our clothes. Your teacher will provide some chemicals for testing. It is easier to test samples of cloth if they are fringed at the edges. Here are directions for some chemical tests:
1. Place a piece of white cotton cloth and a piece of woolen material in small dishes. Cover with 50 per cent solution of nitric acid. The wool fibers will turn yellow. The cotton remain white. If a piece of wool cloth was mixed with cotton, how would the test prove it ?
2. Boil samples of cotton and wool together; then samples of cotton and silk together, for fifteen minutes in a 5 per cent solution of caustic potash. The animal fibers will dissolve, the cotton will remain. Of what use would this test be ?
Fig. 148. - The chemical tests show many things of use in judging materials.
3. Moisten samples of cotton and of wool with Millon's reagent. Place in porcelain dishes and heat gently. The animal fibers will become red; the vegetable are unchanged.
4. Material made of cotton and linen and sold for all linen can be tested. Place fringed sample in a porcelain dish. Heat gently in 50 per cent solution of caustic potash for two minutes. Remove with glass rod and dry between blotting papers. The linen will be dark yellow in color and the cotton white or light yellow.
So we have learned a few tests of different kinds. There are many more. When you go to high school you can learn about others. The Pleasant Valley girls enjoyed making these tests with Miss James' help. Perhaps you may be able to try them with your teacher.
1. Try the above chemical tests with your teacher's help.
2. Try some of the other tests for adulterations.
3. Tell four ways in which materials are adulterated.