I have recently begun to acquire old strops with second elements. Some are obviously fire hose covering. Some are hard and some are soft and at least one gets stiff and hard when wet.(I don't know how else to say it)

Is there some means to know whether a cloth strop is canvas, cotton, or linen, or something else? DON'T TELL ME TO LICK IT! It ain't gonna happen to my hones it ain't goin to happen to my strops.