A Comparison of Several Manufactured Blades

Gillette_blue_blade_x_04

Vintage NOS Gillette blue blade (E3, manufactured third quarter of 1959)

Gillette_blue_blade_x_02

Vintage NOS Gillette blue blade (E3, manufactured third quarter of 1959)

Kai_scalpel_x_01

Kai/Miltex disposable scalpel blade

Kai_scalpel_x_03

Kai/Miltex disposable scalpel blade

Astra_stainless_X_05

Modern Gillette Astra Stainless DE razor blade

Astra_stainless_X_01

Modern Gillette Astra Stainless DE razor blade

olfa_blade_x_03

OLFA disposable snap-blade knife

olfa_blade_x_01

OLFA 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.

olfa_blade_x_05

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.

Feather_AC_SP_01

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.

Shap16k_X

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.

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7 responses to “A Comparison of Several Manufactured Blades

  1. It does appear that the last micron or so is at a steeper angle than 19° – and it doesn’t look like convexing but a separate tiny bevel. How they are putting that last little bit on the very edge would be interesting to know.

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  2. Ah, must be the scale I’m not used to. At that level it sure looks like a tiny microbevel! These blades are likely finished in strip form, right? So they must be doing a power stropping or brushing of some sort. Sure would be interesting to see the factory floor and have access to the processes used.

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  3. I was in Japan, so I got my wife to purchase me a case of Feather Super Pro blades off of amazon.jp. I had my first shave with them last night, and it was a great experience. Feels similar to a straight razor using your progression, right after refreshing.

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  4. Great work Todd! I have found that on some brands of these blades, they need to be stropped or micro-beveled to get them to cutting well, and it can vary from blade to blade even within brands. Take care!

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