For centuries, men have sharpened tools, knives, swords and razors. With the proliferation of disposable utility blades and cartridge razors, what was once a commonplace skill has become a lost art, practiced mostly by knife enthusiasts, hand tool woodworkers and men who shave with straight razors. Whether sharpening by hand with hones and abrasives can produce a finer edge than industrial scale, mechanized sharpening seems likely, but it is something we will investigate. Undoubtedly, the modern preference for mechanized and disposable sharpening is the choice of convenience rather than a confirmation of quality.
In principle, there are two general approaches to quantifying “sharp” or the keenness of a blade’s edge. The simplest and most common is through comparison and evaluation of use. Comparing the force to cut, the smoothness of the chiseled wood, the thinness of the sliced vegetable, or the closeness of the shave provides a relative quantification of sharp. Such comparisons are more than sufficient to allow a practitioner to develop and evaluate a honing procedure. To a Scientist, this phenomenological approach begs the questions of why? and how? and provides little insight into how the process can be improved.
My approach will be to use electron microscopy to physically observe the geometry and polish of the edge and to quantify the edge width and bevel angle. The goal is to provide an understanding of what is happening a the blade’s edge. The centuries old design of a straight razor provides the ideal system for scientific study of sharpening. Honing on a flat surface with the bevel and spine contacting the hone fixes the angle of the apex. The steel used in a straight razor is hardened and tempered to optimize the achievable keenness. In our experiments, the use of a straight razor will allow us to fix the honing angle at the value determined by the spine thickness and blade width.