We have already learned that materials differ from each other, first, because of the fiber from which they are made and second, because of the weave by which they are constructed. A third way in which materials differ is according to their color or pattern. Some materials are white, some materials are dyed a solid color, some materials have a pattern woven into the cloth, while in others the pattern is printed on the cloth. It will be easy for you to sort your samples into these four groups.
How Materials Are Made White. - Have you ever seen tablecloths or towels spread out on the lawn to bleach in the sun? Sometimes housewives buy tablecloths, towels or sheets that are unbleached. Long ago it was the custom to bleach cotton and linen materials by spreading them out on the lawn for the sun to whiten. At the present time most bleaching is done by using chemicals. It takes many weeks to bleach materials in the sun but it can be done by chemicals within a few hours. In this process of bleaching by means of chemicals there is danger of the fabrics being injured by over-bleaching. This causes holes to appear in the materials after they have been used only a few times. Examine your samples to see if you can find some that are bleached and some that are unbleached.
How Materials Are Colored by Dyeing. - Sometimes cloth is "piece dyed" which means that it is dyed after the cloth is woven. Dyeing is also done before the cloth is woven and in this case it is spoken of as "yarn dyed." When material is "piece dyed " it must of necessity be all of one color but when the yarns are dyed before they are woven it is possible to weave different colored yarns together in order to produce patterns. The stripes and checks in ginghams are produced in this way. Chambray is a material that is always made with colored warp threads and white filling threads. Is this piece dyed or yarn dyed? Changeable colored silks are always made by combining two colors, one in the warp and one in the filling thread. Which of your four piles of samples was produced by piece dyeing? Which group of samples was produced by yarn dyeing?
Printing Fabrics to Obtain Colored Patterns. - Patterns are not only produced in materials by means of weaving but by a process of printing. Materials may be printed in much the same way as the daily newspaper is printed. The cloth is run between the copper rollers of a printing press on which the pattern is engraved. The pattern is printed on the cloth as it passes between the rollers. Have you ever stamped a pattern on a piece of cloth or a paper from a woodblock? This was the first method by which patterns were printed onto cloth. Printing cloth by means of the roller press makes it possible to do it very much more rapidly. Sometimes the pattern is printed on the yarns before they are woven. If you have studied about rugs you will remember this is done in the case of tapestry Brussels and velvet rugs.
In your group of samples of printed materials you will probably find percale, calico, printed silks, cretonne and challie.
In Your Notebook. - Mount samples of each of the following kinds of material in your notebook: unbleached material, bleached material, plain colored material, a material with a woven pattern, and a material with a printed pattern. Make a label explaining each of the samples.
A Four-minute Test. - 1. Write as many names of materials made with printed patterns as you can in four minutes.
2. Write as many names of materials made with woven patterns as you can in four minutes.
Trade your paper with another girl and check her list of materials. Give five for each correct answer.