Thread: Korn's patent on bellied grind

Happy Holidays all!
Look what I've stumbled upon: apparently in 1902 G.W.Korn has patented the double-concave or what we now know as the bellied grind.
What I find particularly interesting about this patent is his description of this invention's purpose - in the second paragraph:
"The object of my invention is to so construct a razor that it will have concave faces along the cutting edge and yet be firm in action. Heretofore the razors mostly in use were of two kinds, the one known as the "English hollow ground", which has concave faces that extend from the cutting edge to the very back of the blade. These have practically ceased to retain their hold upon the market, because of the vibratory character of the edge, since the extended concavity made the cutting edge vibratory to such an extent as to render the instrument itself objectionable in use. The cutting edge appears to lose its straight line and to assume apparently an undulating form in action whenever it meets with an obstruction. The other kind of razor largely in use is known as the "Hamburg concave", which had the back portion of the face concave and the edge portion substantially convex and which, though producing a satisfactory cutting edge when new, was subject to the serious objection that after short use it could no longer be honed, owing to the fact that the ridge of the convexed portion would stand outside of the line drawn from the extreme back to the extreme cutting edge, thereby preventing the edge from touching the hone."
And I've always thought of extra hollowed grind to originate in Germany, and to be a rather popular one - especially in the later days of straight razors, whereas what he describes as the "Hamburg concave" hasn't hold much. Go figure.

Interesting, didn't know that the "English hollow ground"(full hollow?) was so objectionable. What is this Hamburg concave they are talking about? Don't know if I've ever seen one.

Interesting find but I have a hard time visualizing what is meant by "English hollow ground" and "Hamburg Concave". I do have a few razors marked "Hamburg Ring" which iirc are very hollow ground. I also have a few that are "bellied hollows" and they appear to be what is described in Korn's patent application. I have also read somewhere iirc that the closer to the edge the belly is the higher the quality of the razor grinding is. All I can say is the either the very hollow ground or bellied hollow ground razors I have give excellent shaves.

Bob

My first straight razor is a 'Hamburg Ring'. The belly is definitely there. Easier felt than seen.

Originally Posted by bluesman7

My first straight razor is a 'Hamburg Ring'. The belly is definitely there. Easier felt than seen.

I'd bet a few people have been using a bellied hollow without even realizing it.

Yes, most bellied hollows are easier to feel with your fingers than see unless the lighting is just right on the blade. Could easily be my Hamburg Ring razors are bellied I just don't recall at the moment.

Bob

Lots of razors have bellied grinds. Korn's patent was an extreme example, a double concave.
While most can only be detected by feel or looking at the end, Korn's grind is very prominent. Pretty stiff razors.
I have seen it on Robison and Clauss razors as well as Cattaraugus razors like this one.

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