A Comparison of Several Manufactured Blades

Vintage NOS Gillette blue blade (E3, manufactured third quarter of 1959)Vintage NOS Gillette blue blade (E3, manufactured third quarter of 1959)Kai/Miltex disposable scalpel bladeKai/Miltex disposable scalpel bladeModern Gillette Astra Stainless DE razor bladeModern Gillette Astra Stainless DE razor bladeOLFA disposable snap-blade knifeOLFA disposable snap-blade knife

All four examples have a cutting edge with a width less than 200nm, although the final bevel angle varies from 21 degrees for the Blue Blade to more than 40 degrees for the Olfa blade. The Olfa blade also has a small burr on the edge which reduces the effective keenness.

Edge Burr (foil or wire) on the Olfa snap blade.

At minimum, these examples demonstrate the scale at which we need to resolve and image features is well under one micron.

With our definitions of Keen and Sharp we can see that all blades have similar keenness, but the razor blades are sharper than the scalpel and utility blades. The images below demonstrate that the Feather Super Pro Artist Club blade is much keener than other manufactured blades, but is not nearly as sharp as a conventional straight razor.

Cross-section of a Feather Super Pro Artist Club blade, often considered to be the “sharpest” commercial razor blade. The blade is coated with a fluoropolymer that is removed with the first use. The Apex width is approximately 50nm, keener than any of the commercial blades shown above. The width at 3 microns is 1.4 microns, due to the 19 degree final bevel angle.Cross-section measurements of a conventional straight razor, honed to a 16k whetstone, prior to stropping. The edge width is on the order of 100nm, less keen than the Feather Super Pro; however, the width at 3 microns is only 1.05 microns, significantly Sharper than the Feather blade.