Care and feeding of a Kamisori

As someone who uses and sells Kamisori, it's probably a good idea for me to know how to take care of them. Luckily, now I do.

One of the problems specific to Kamisori is the flattening of the Omote.

As I discussed in a previous post, the omote of a Kamisori really should be slightly hollowed out, visible as an arc in the blade.




However, the hollow is very slight, and over time the particular honing process of a Kamisori will lead to a flattening of that hollow; in some extreme cases (after several decades) the blade can be come completely flat.

In order to prevent this, then, maintaining the kamisori requires the owner to rehollow the blade, either by himself or by sending it back to the maker.

I'd seen several websites where kamisori owners used hand grinders (like a Dremel) and ground it out but frankly, it looks terrible. My barber used a file for his razors, and it honestly wasn't too bad looking, but I never really thought of a better way to do it.

Then last week or so, Takami-san of Takamitou cutlery sent me an email about his experience with just this problem.

As I described in that previous post, one of the razors I had from him did not have a sufficient arc and so was difficult to hone and use. He fixed it for me, and he then posted on his blog how his teacher showed him to take care of a kamisori.

You can see it here in Japanese, but basically you use a tool called a "Sen" or "Tombosen" (don't bother looking it up in Japanese, I searched for a week and found only one reference on a blacksmithing site).

Here's a pic:



Basically, it's a bar of hardened Hitachi Aogami steel, with one end ground into a very heavy blade, something like a machinist's hand scraper. It's got a very thick bevel, so it will stand up to the abuse of scraping steel, but is still quite sharp. Simple, and kind of elegant.

Here it is in use (That's Takami-san, from his blog):



This is the one that Takami-san made for me, and I tried it out on my "tester kamisori".





Basically, you just scrape. It takes some practice to hit the right angle, and you shouldn't put any weight or strength into it, just let the Sen do the work. Takami-san recommends clamping the kamisori to a board, or cutting a notch into the board to hold the tools at the proper angle, to do it.

It is a slow, but very precise, way of removing steel, and very gentle on the steel. When performed frequently, it'll keep your razor in shaving shape for decades.