A more scientific method was proposed by Mr. Kingsbury in his pamphlet on the razor, namely the examination of the entire edge with a magnifier, and which process when applied in a sufficiently powerful degree will doubtless exhibit the causes why the razor fails in its purpose, and which are sometimes threefold, namely first the razor may be notched, secondly it may have a loose pliant film or wiry edge, or thirdly, instead of a keen acute edge it may be blunt and obtuse, which is generally due to the excessive use of the razor strop; upon each of these considerations some few observations will be offered.

First, notches are liable to occur in a razor from the blade having been overheated, either in the forging or hardening, a fault which is irretrievable, as it renders the steel permanently brittle, and altogether incapable of receiving a fine acute edge, as the particles of the metal break away at the extreme edge on the hone. The brittleness may occur in a somewhat less degree, when the razor without having been overheated is simply left too hard, so as to require to be let down or. tempered a little lower than at first. Secondly, the wire edge generally occurs from the hone being too much used, as when the two faces of the wedge are rubbed away beyond that point at which they first meet, the slender film of steel commences to form, because the extreme edge is then so thin that it bends away from the hone instead of being rubbed off. The wire edge is more liable to occur when the one side of the blade is more whetted than the other, and if it be obstinate in its resistance to removal, it frequently indicates further that the blade is too soft, as if the razor blade be made too hard, the metal will be brittle instead of flexible, and the thin extremity break off instead off forming the filmy edge.

The temper of the blade ought to be such as to be indisposed to become either permanently notched or wiry from the action of the hone. But in the application of the various grinding and polishing wheels, especially the latter, there is always some risk, as the temptation to expedite the work causes too much vigour to be occasionally used, thereby giving to the blade so much heat as to reduce its temper; an error the unscrupulous may easily gloss over, by touching the work more lightly, and thereby removing the colour, or that index whereby the temper of the instrument is commonly estimated. But the experienced cutler is generally able to distinguish by the feel of the cut, or of the action of his own particular hone, between such blades as either exceed or fall short of the appropriate temper.

Thirdly, in a new or a recently ground razor, the thick obtuse edge shows that the blade has not been sufficiently rubbed on the hone, and in a used razor, it more commonly indicates that partly by the using of the razor, and partly by its being intermediately stropped to renovate the edge, it has been too much rounded; so that instead of the two narrow facets constituting the edge being plane surfaces and meeting at from 17 to 20 degrees as left from the hone, they are seen to have become considerably rounded, so as probably to meet at more than double the original angle, a condition explained by the diagrams figs. 1037 and 1038, in which for perspicuity the extreme edges are shown about twenty times their true size. This fault or the rounded edge is also readily detected with the magnifier, and is almost sure to occur from the use of a soft strop, as the leather immediately against the edge from being indented, rises as an abrupt angle and mutilates the keenness of the blade. If however the razor at any of its stages of manufacture or setting have been treated without uniformity, it may possess at different parts of its edge all these errors, but which is less to be expected than that the one error should prevail.

Figs. 1037.

Setting Razors Part 2 30011

1038.

Setting Razors Part 2 30012

If neither of the above three faulty conditions are discernible by the careful use of a lens of one half to one third of an inch focus, (or of a linear power of twenty or thirty,) such razor will in general be found to act with satisfaction, but the keenest razor when delicately examined with a lens of one fifth to one tenth of an inch focus, (or a linear power of fifty to one hundred,) or still better with a microscope of not less than equivalent power, will present a faintly undulating and irregular edge, which resembles rather a ripple mark, than the angular teeth of the edge of the saw, to which it is usually compared. Indeed the edge of a razor of ordinary quality, bears the microscopic examination much better than might be expected; but as no surface polished by art is free from scratches, it must happen that every such scratch when continued to the edge formed by two planes meeting at so small an angle, deprives the otherwise continuous edge of a small portion of its material, and thence constitutes a notch, but the notches are the smaller, the finer the abrading surface used in producing the edge.

When however the errors are so minute as to require to be thus magnified some fifty or one hundred times, to render them visible, they are too minute to be detected by the skin, the nail, or the employment of the instrument on the beard. Having explained the good and bad condition of the razor, the practice of setting the instrument will be now the more easily understood, and it is proposed first to describe the sharpening of a new razor, and then that of one which has been rendered dull by use.

Various kinds of whetstones are more or less used in sharpening razors, commonly in pieces measuring from eight to ten inches long, by one and a half to two inches broad, and great importance is deservedly attached to their being perfectly flat on the face, with which view they are occasionally rubbed on a large gritstone with water, but in use they are always supplied with oil and kept remarkably clean.