Questions
1. What is the effect of the acid solution upon the fabrics?
2. Would they necessarily withstand the effect of perspiration, even if they did withstand the acetic acid solution? Why?
Experiment 51—Test for Determining Dressing
Apparatus: Magnifying glass, porcelain dish.
Materials: Various fabrics.
Reference: Textiles, page [242].
Directions
1. A great many cotton fabrics such as muslin often contain considerable sizing or dressing. In order to examine a fabric and determine whether too much dressing has been used, take a small sample of the fabric and crush it in the hand and rub it together, so that the dressing is removed and the quantity employed may be determined. If much dressing has been used, dust will be produced in rubbing. Prick the surface with your finger nail. Notice whether the starch comes off. Then wet your finger and rub it on the cloth and allow it to dry. Does the gloss disappear?
2. Another method is to hold the sample before the light and notice whether you can recognize the dressing. Examine the sample with a magnifying glass (or pick glass) and notice whether the dressing is superficial or penetrates the substance of the fabric.
3. Would you buy low priced cotton goods with a thick gloss and pasty look?
4. Notice the effect (lusterless) of fabrics containing much dressing after washing.