1. Take a sample of a woolen fabric 12 in. by 20 in. and pour hot water over it and leave it immersed over night. Then dry it in the morning at a moderate temperature without stretching. Then measure its length and divide the difference in lengths by the original length. The quotient multiplied by 100 will give the per cent of shrinkage.
2. Repeat the same experiment with a worsted fabric, and with a cotton fabric.
3. Why does the woolen fabric shrink more than the worsted?
Experiment 37—Test of Fastness[28] of Color under Washing
Apparatus: Porcelain dish, soap solution.
Materials: Cotton and woolen fabrics.
Reference: Textiles, page [242].
Directions
1. Colored goods and printed fabrics should withstand the action of washing. They require more care than white goods and should be soaked in cold water containing very little soap and no soda. They should be dried in the shade as a very hot sun will fade them. If it is necessary to dry them in the sun be sure that they are dried wrong side out, as direct sunlight fades them about five times as much as reflected light.
2. All colored fabrics should stand mechanical friction as well as the action of soap liquor and the temperature of the washing operation. In order to test the fabric for fastness a piece should be placed in a soap solution similar to that used in the ordinary household, and heated to 131° F. The treatment should be repeated several times.
3. If the color fails to run it is fast to washing.