Thread: experiments

Finally found the Verhoeven paper, which should help correct the overemotional rhetoric and ad-hominem attacks in this thread.


Experiments on Knife Sharpening
September 2004
Prof. John Verhoeven
Emeritus Professor
Department of Materials Science and Engineering
Iowa State University

Experiments on Knife Sharpening


On page 19, figure 23, he shows a blade sharpened on a 6000 grit waterstone, at 3000x and 800x resolutions. Notice how small the grooves are, even at 800x magnification.

On page 30, figure 37, he shows a blade with a secondary bevel formed on chrome oxide. He doesn't give the grit, but he does describe it as the standard chrome oxide block sold in woodworking stores for honing chisels. At best this is the 0.5 micron Lee Valley block, at worst it's the coarse stuff that's blended with other abrasives. If it's the 0.5 micron chrome oxide then the grit is comparable to the grit of a 30k Shapton (my Shapton is 0.48 micron). Even at 3000x, the grooves in the secondary bevel are very thin and very shallow, and are therefore unlikely to be visible at 25x as the author of that linked article claims. Admittedly I'm comparing a 0.5 micron paste to a 0.5 micron stone, but Verhoeven shows an awful lot of photos of 1k, 6k, and 8k honing marks at a variety of resolutions, and the marks from even these relatively coarse hones are surprisingly small.

I do not apologize for being negative about the linked post, nor for being contradictory about his assertions. But if Prof. Verhoeven's pictures are accurate depictions of micron and submicron-scale honing marks, then it is clear that the centimeter-scale photos in the linked thread must be showing much larger honing marks and not the 0.5 micron - 0.2 micron striations that the Shapton and Nakayama hones would be producing.

I hope I haven't soured you on the Verhoeven paper, but it is well worth reading front to back. He shows comparative micrographs of commercial Gillette razor blades and a straight razor that was honed by somebody that used it, and the straight razor comes off looking quite well. And the photos are quite eye-popping.