Clothing Fabrics - Tests For Silk
( Originally Published 1924 )
Since wisdom in the selection of silks is a valu-able aid to the one who believes in economical efficiency, a few tests are given.
Burning Test :
Pure dye silk, whether fabric or thread, when burned leaves a crispy coal or ash.
Weighting with sugar leaves an ash like burned sugar. Weighting with iron leaves a soft reddish ash. Weighting with tin leaves a firm black ash, resembling cloth or thread.
Artificial silk, because it is made from a cotton or wood fiber, burns like vegetable fiber. In white, true silk will turn yellow if tested with nitric acid; but if artificial, it will not. Artificial silks have a tendency to dissolve or become weakened when boiled.
Tests for Mixtures:
In testing for silk and wool a sample is placed in cold concentrated hydrochloric acid from two to five minutes. Silk dissolves, but the wool is hardly affected.
In testing for silk and cotton, a sample is boiled in caustic potash—which should be kept away from hands and clothing. The animal fiber will dissolve, leaving the cotton.