The other day, I was digging around the vastness that is the internet and came across a fascinating post from one of my favorite woodworking bloggers Wilbur Pan, about the metal used in Japanese tools. Wilbur is a talented craftsman with an immense amount of knowledge about Japanese tools and woodworking.

The following is blatantly stolen borrowed from Wilbur’s blog Giant Cypress back in May of 2014. 

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Shop Talk Live, Fine Woodworking’s podcast, was kind enough to read part of an email I sent them regarding an episode where they fielded a question addressed to Mike Pekovich on Japanese chisels. They discussed the factors that go into the price of the more expensive Japanese chisels, and the use of wrought iron sourced from old anchor chains in making these chisels came up. I sent them an email to clarify the issue. They didn’t have the time to read the entire email, so I thought I’d provide it below.

Dear Mike and Matt,

I heard the last STL episode, where you talk a bit about Japanese chisels. There are some ways that you can tell the difference between a cheap Japanese chisel and a higher quality, more expensive one. The first is the attention paid to the filing and finish of the chisel itself. Just like a relatively cheap piece of furniture will likely have a mediocre finishing job, a cheap Japanese chisel will have areas where the filing and the shaping of the chisel is less refined.

The second way is to look at the lamination of the hard and soft steel layers. Better Japanese chisels will havea thinner layer of hard steel that is very even in thickness, and that is slightly turned up at the corners. Cheaper Japanese chisels will have a thicker layer of hard steel, that is not laminated evenly across the width, and is less attractive to look at. It may sound counterintuitive that a better chisel has a thinner hard steel layer, but the thinner the hard steel layer, the easier it is to sharpen. It is also harder to forge weld a thinner piece of hard steel without fracturing the chisel, so some of the cost goes into the skill of the blacksmith making the chisel.

There is a reason why wrought iron chains and bridge steel from the 19th century are a sought after source for the soft layer of Japanese chisels (and plane blades). It’s not just marketing. It has to do with the method of manufacture of wrought iron. Up until the end of the 19th century, wrought iron was made by a different process than what is used today. As a result, the wrought iron of the 19th century is softer and easier to abrade than modern day wrought iron. Modern day wrought iron also tends to have higher levels of alloying agents in it, which also makes it harder to abrade and more durable than old school wrought iron.

Of course, in most situations you want your wrought iron to be harder and more abrasion resistant, except if you are making a Japanese chisel. That’s why Japanese blacksmiths seek out those old boat anchor chains. They are looking to make the soft layer as soft as possible. It’s not impossible to make a Japanese chisel out of modern day wrought iron, and having the soft layer made out of modern day wrought iron is still better than making the whole tool out of hard tool steel. But using wrought iron from the 19th century results in a tool that is nicer and easier to sharpen.

This may seem like an insane level of attention to detail, but I would put it in the same category as making sure you are using straight grained pieces of wood for the rails and stiles when making a panel door, and using the more figured wood for the panel. You can certainly find panel doors on kitchen cabinets where no attention was paid to grain direction, and the doors more or less work fine. But it’s a lot nicer if you use the proper pieces of wood in the places where they should go. Another analogy would be that the difference between 19th century wrought iron and modern day wrought iron is like the difference between using modern day pine from the big box store and old growth pine where the growth rings are nice and tight.

Take care,


Wilbur

*Anchor image from the Metropolitan Museum of Art