20th Century Correspondence School, Shaving Made Easy (1905)
“ There are two ways of judging of the temper of a razor; one of these is practically infallible—viz:—the examination of the blade and its edge by means of a microscope. It will be readily admitted that the real excellence of a razor is in direct proportion to the firmness and unbroken regularity of its edge. When a razor is too brittle, in consequence of having been either to much heated in the process of hardening, or not sufficiently cooled in that of tempering, it cannot possibly take a good cutting edge, no matter how much skill may be employed in honing and stropping it. ”
