How to Sharpen Japanese Chisels

This isn’t going to be what you think. I could give you a method to get an aesthetic and a result, but I think you need some background based in reality, and my reality is having bought probably 200 chisels from japan, and viewed thousands or tends of thousands for sale.

Myth vs. Reality

There are two myths that I can think of, and they don’t present themselves often in well used tools. First, the myth that everyone in japan sharpens chisels over a great long period of time with extreme care and with perfect bevels.

They don’t. I have received a single set of used chisels that were actually being used that were perfectly prepared. Someone was carefully using them and the very tips were perhaps ever so slightly rounded. I mean the last couple of thousandths, but the bevels were flat and cosmetically nice, and the backs were flat.

I have never received another single set of chisels that were in use that were in such a condition.

The second myth – that the genuine tools are tempered extremely hard at some level that doesn’t make any sense. By this, I mean that Japanese chisels typically are harder than western chisels. It’s the nature of the steels, white 2 and 1, or other similar surplus carbon steels. Hitachi’s tempering range starts around 325 degrees F, which will result in hardness around 66 with the right choice of steels. Such a chisel will still behave as a hard tempered tool (chippy, etc) in hardwoods. I have seen accounts of people claiming their favorite maker tempers chisels at 100 degrees C. Or the boiling point of fresh water at sea level.

It’s possible that a maker would do that, but it will not result in a good-to-use chisel. It will provide someone who wants to temper their own chisels with a starting point.

To pretend that a chisel that chips easily even in sharpening is somehow a good chisel is nonsense.

When I receive chisels from tool lots in Japan, I always try to find chisels that have been some-used , and sometimes that means getting 20 when you’re looking for 10 of the group, or perhaps in combination with blades.

When a chisel or three is undertempered, it is almost always erratically sharpened or hardly used. Neither is a good thing. A trip to a tempering oven sans handle at about 350 degrees will still result in a very hard chisel (guesstimate, 65 hardness, could be still toward 66) that can suddenly hold its edge in hardwood.

Back to the perfectly prepared set of chisels that I had – what was the key? I don’t know for sure, but they were one of the softest sets of well made chisels I’ve ever found. I would imagine that an experienced user got his or her hands on them and realized how compliant they were on good quality stones and realized they were just the ticket. I have a very developed sense of estimating hardness of plain steels on stones, and would estimate that set of chisels to be about 62 hardness. White steel has nothing in it to resist wear, so a set of chisels with a good soft lamination at that hardness will sharpen with little effort.

If they Weren’t Flat, How were they Sharpened?

Most of the chisels I’ve come across have a little bit of convexity on the primary bevel, sometimes with a primary that wasn’t that neat, and then some steepening near the edge.

Why? Because you can remove the bulk of the bevel that way and then focus the fine sharpening on the tip of the tool and zero in to the tool being durable. that’s my assessment, at least. That method also takes some of the pressure off of a natural stone being able to finish tools quickly. Most tools are factory finished on a very large diameter wheel, even the expensive ones, and you get to establish a flat bevel if you like that.

I would like to show you an array of pictures, but I never thought much other than using the new sets as a place to experiment on expediting setup/prep. so I have hollow ground and then honed out the hollow or flat ground almost every chisel I’ve ever received experimenting with ways to get that nice aesthetic bevel and finish it without getting bogged down in the idea that what’s touching the edge should touch the whole bevel.

Too, the finest stones, even the natural ones, won’t leave a very subtle but crisp defined soft to hard line. Anything other than wrought, and even wrought iron to some extent (usually found on plane irons, but sometimes on chisels) will become bright. it’s nicer to keep the bevel maintained with a fast synthetic stone followed by a relatively fast natural stone (guess what- a slurried washita leaves a divine finish), and then use something exceedingly fine on the tip of a chisel.

So, How Should You Do It? The Sharpening?

First, understand what allows the edge of the tool to be held without chipping. That means you can’t look at a piece of paper, and say “oh, two flat planes meeting at 30 degrees” and expect success. You have to find it. Obviously, I have a bias toward things that round the last several thousandths of an edge because the durability is outrageous and the sharpness is pretty divine, too. but you can use very small bevels – I think a very slow stone and doing this freehand is good. You’ll learn touch and maybe get better results than a jig -not to mention faster.

Notice also that when you read Odate’s book and see other pictures of actual users of chisels, you will find the silicon carbide stone is in the set to deal with damage. If you have a chip and you’re using a 1500 grit stone, there’s no virtue in that. It’s got nothing to do with using the tools.

Don’t deprive yourself of learning what works by experimenting. Get on ebay and find tools that look like they’re reasonably well finished but not prissy. There’s no great difference between the better tools I’ve gotten for $15-$20 per, maybe from time to time with an adjustment to temper, and any of the three Kiyotada chisels that I have and have used. If I’m honest, those chisels are like the three bears. Two are parers – one is too hard tempered and needs to be adjusted – it will not hold up in use, and it’s so hard that it will crumble on a coarse sharpening stone. The second is a little softer than expected, and a more recent mortise chisel is excellent – just in the middle. More recent meaning that Stan C. got it for me as new old stock from a dealer’s back room in Tokyo. An excellent chisel, very subtly finished, but it’s still a chisel, and it will still chip if you pry with it and it will not work for three weeks of continuous use or anything like that.

So, lesson? other than not overheating a chisel, use stones that are efficient and that are fast enough that you will sharpen often enough that you’re not wasting time avoiding sharpening and using dull tools.

Lastly – Who is Telling You How Tools are Prepared in Japan?

A lot of the information told to western buyers is woo. That a routine white steel chisel would be $300 per is woo. That a typical user has some $3k natural stone in a shroud to finish their chisels is woo.

It’s not difficult to get on a proxy link to yahoo auctions in Japan (Buyee, for example) and look at tools that have been used. You’ll be able to find everything from the same kind of “made for westerners” $4k chisel sets to well made used chisels made for experienced workers selling for $150 or a little more. Try to find a set of chisels that are significantly shortened but that retain perfect edges and a perfectly flat bevel. I think most professional users were more pragmatic than that.

Maybe another day, I will make a post showing the process of setting up and sharpening a Japanese chisel. It should be quick and intuitive, not punishing.

Like Colombo used to day – just one more thing. Am I trying to make excuses for myself? No – when I used Japanese chisels (sparingly now that I make my own chisels), I would make them tidy for pleasure. As with many things, it wasn’t a matter of just getting the tools neat. It was making them have aesthetic appeal, but learning to do it really quickly. Below is a picture of a chisel that I had sharpened that was in my “user” set. White 2 chisels with a wrought backing. They, too, were just a touch soft. Guess? 63/64 – supple on natural stones. This chisel was serving a second purpose sometimes – demonstrating the finish left by a finishing stone that I was offloading on etsy.

I really like the way this looks. Even the one single set that I found that was prepared nicely still wasn’t done was well as this. The rest, not remotely close. And people still managed to use them enough to get the handle and the blades shorter than they were when new.