4. Boil a piece of the sample for five minutes in a solution of household lye. To make the solution put two teaspoonfuls of the household lye in a pint of water. All the wool will be destroyed and the cotton left.
Instead of using cotton as a substitute for wool, the manufacturer sometimes uses wool a second time. This is generally called re-manufactured wool or re-worked wool. Old woolen garments and tailors' scraps are torn up and the wool fibers used again to make another piece of material. If the wool rags from which the re-manufactured wool is made are new and of good quality, the material will also be of good quality. However, if the rags are old and worn, the material will not be of good quality, because the fibers are short and broken. Under the microscope they often show that the scales have been destroyed. So even though a material is "pure wool," it may be of poor quality. When we find a great bargain in woolen material we should be sure that it is not made of poor quality re-manufactured wool. Since there is no sure way to detect the presence of re-manufactured wool, it is best to buy from reliable merchants. Sometimes the price of the material is an indication that it is made from good quality wool.
For Your Notebook. - 1. Test some samples of woolen materials according to the four tests described above.
2. Describe the results and mount the samples if possible.
A Story to Write. - Tell the story of the life of a wool fiber. Start with the day when it was cut from the back of the sheep and tell how it was made into cloth, used for some garment and re-manufactured into more cloth.
How We Can Judge the Quality of Silk in Ribbons, Stockings and Dresses. - 1. We can judge the quality of a piece of silk to some extent by the firmness of its weave in the same way that we judge the quality of weave in a piece of gingham.
2. You have learned that some materials are made from long, unbroken fibers and other materials are made from the short fibers called waste silk. How can you judge this quality of silk fibers? See page 139 if you have forgotten.
3. You will remember that in the finishing process silks are often weighted to make them seem heavier and firmer. A way of testing silks for weighting is to burn the sample. It is amazing to see what happens when a piece of heavily weighted silk is burned. The cloth retains its texture and shape, even though it has been burned. This means, of course, that the silk fibers have been burned out and the metal weighting has been left. If the sample should be all silk it burns down to a little ball.
4. Again we find that cotton is used to imitate another fiber.
Cotton is much cheaper than silk, and, since mercerized cotton has a silky appearance, it is often used to imitate silk. What we suppose to be silk sweaters and stockings are often made of mercerized cotton. Some pongee materials are also made from mercerized cotton. An excellent way to distinguish silk pongee from cotton pongee is by the burning test. Silk burns slowly and chars like wool. Do you remember how cotton burns? 11
5. Burning can also be used to determine the presence of artificial silk. Since artificial silk is generally made of cotton waste or wood pulp how would you expect it to burn? It is hardly necessary to burn artificial silk to detect its presence. Its high luster and stiff, coarse fiber are very obvious.
For Your Notebook. - Mount samples of your hair ribbons and ties with a written description of what happened to each sample when it was burned.
Adulteration in Materials. - You have already learned how one textile fiber may be made to imitate another. For example, mercerized cotton and artificial silk may be sold for real silk, or cotton may be made to look like linen. Cotton and wool may be mixed and sold for pure wool. All these things and many others which we have not yet studied are spoken of as adulteration in textiles. Formerly, the same kind of adulteration was common in foods. This became such a serious matter that laws were passed which make it an offence against the law to mislabel foodstuffs. At the present time there is an attempt to pass similar laws for the labeling of textiles. If such a thing should come to pass one could be more certain of the quality of the material one buys. Even now there are certain guaranteed textile products on the market which can be relied upon.
1. Can you name any guaranteed garments or materials that are sold in the stores in your town?
2. Write a paragraph for your notebook telling what you consider is your duty as a good citizen in regard to adulteration of materials. Suggestions for Individual Reports. - 1. Your report should be presented to your class, and it should be your aim to tell them some interesting facts in a clear and definite way. It will make your report more interesting if you have pictures, diagrams, charts, drawings on the blackboard or actual materials to illustrate your talk.
2. Decide how long the report shall be. Plan your own report so as not to take more than your share of time.
3. Elect a chairman who will be in charge of the program on the day when the reports are given.
4. The list of references at the end of this chapter will help you in working up your report.
5. Choose one of the topics listed below for your report or perhaps you can think of some other topic. How broadcloth is made. How the felt in a school banner is made. Old and new methods of bleaching linen. Effect of weighting silk.
Invention of the stocking frame. How knitted underwear is made.
Spun silk and how it is used.
Other fibers used for textiles.
Legislation to control adulteration in textiles. How gloves are made.