Automation Makes Traditional Japanese Wood Finishing Easier

Unless you move in architectural circles, you might never have heard of Yakisugi. But as a fence builder, [Lucas] over at Cranktown City sure has, with high-end clients requesting the traditional Japanese wood-finishing method, which requires the outer surface of the wood to be lightly charred. It’s a fantastic look, but it’s a pain to do manually. So, why not automate it?

Now, before we get into a whole thing here, [Lucas] himself notes that what he’s doing isn’t strictly Yakisugi. That would require the use of cypress wood, and charring only one side, neither of which would work for his fence clients. Rather, he’s using regular dimensional lumber which is probably Douglas fir. But the look he’s going for is close enough to traditional Yakisugi that the difference is academic.

To automate the process of burning the wood and subsequently brushing off the loose char, [Lucas] designed a double-barreled propane burner and placed it inside a roughly elliptical chamber big enough to pass a 2×8 — sorry, metric fans; we have no idea how you do dimensional lumber. The board rides through the chamber on a DIY conveyor track, with flame swirling around both sides of the board for an even char. After that, a pair of counter-rotating brushes abrade off the top layer of char, revealing a beautiful, dark finish with swirls of dark grain on a lighter background.

[Lucas] doesn’t mention how much wood he’s able to process with this setup, but it seems a lot easier than the manual equivalent, and likely yields better results. Either way, the results are fantastic, and we suspect once people see his work he’ll be getting more than enough jobs to justify the investment.

21 thoughts on “Automation Makes Traditional Japanese Wood Finishing Easier

  1. The way we do dimensional lumber is very surprising: we take the dimensions in millimeters. There are no other steps.

    2×8 only measures 1.5″ by 7.25″, so that’s 38×184. Our standard sizes differ of course, but you can get Douglas pine boards in 38×175 or 38×200.

    1. Note: If your 2×8 only measures 1.5″ by 7.25″ , they you are likely using 2×8 S3S boards rather than true 2×8 boards. The difference being the SnS boards have been surfaced on n sides (and slightly smaller due to material being removed).

      1. Not quite: 2×8 is are the dimensions of the raw lumber, before being dried. During drying the wood shrinks; the exact final dimensions are not rigidly controlled in most lumber sold for framing — and quite often the drying process puts a warp in the board; it is assumed that the overall framing design will pull it back to straight.

        If you’re actually surfacing the lumber you’re probably looking at wood sold specifically for furniture. I don’t know much about that, but it’s a different sort of thing than wood sold for fencing and framing.

        1. You are correct that wood does shrink when dried, but drying wouldn’t account for the “shrinkage” the OP has observed. That wood is SnS cut, maybe S3S or S4S.

          SnS is usually used where the timber may be exposed, and the ‘n’ number is basically the number of sides that are exposed. Probably the biggest use you will see is decking. But I’ve seen it used in a lot of fences where people care about aesthetics. Sometime it used inside houses where timbers may be exposed after sheet rocking (staircases, etc.).

          I don’t know of instances where this is used in furniture. If you are making furniture you are most likely going to cut to dimension and then surface it. I don’t think it make sense to pay extra for 2×4-s4s, then cut it down and then have to surface it again yourself.

    2. Wow, so when you buy a board from the hardware store it has the actual dimensions advertised? It isn’t annoyingly a little bit smaller? Amazing!

      I have heard all the descriptions of why this is done in America, and all of them are total bunk. It’s because this is the nation of P.T. Barnum and they can make you buy a 2″x4″ board that is actually 1.75″x3.5″ and people will bend over and take it. That’s it, that is why

    3. (Sarc on) Not sure where you even buy boards in metric dimensions. (Sarc off)

      ‘Round here, HomeDepot or Lowe’s do “do metric”. Had a hevkuva time finding a 25’ tape measure with both metric/imperial markings. (Yes, they do czrry one or two, but one broke the very fist day)

    4. As someone living in metricland (Norway), I know the dimensions are available in mm for anyone who wants them. I don’t think I’ve ever heard anyone use those numbers though – a 2×4 is a 2×4 and a 2×8 is a 2×8, if only in name.

  2. The answer is obvious, you don’t automate it b/c you’re going to lose all those young and upcoming martial arts masters. If they don’t paint the fence, Cobra Kai is going to take over.

  3. “It’s a fantastic look, but it’s a pain to do manually. So, why not automate it?”

    Well, if you’re actually in Japan and it’s your job then they will purposely avoid avoid automating certain things to ensure people have jobs. Silly but true.

    1. Yeah, silly Japan with its native industry! Don’t they know you’re supposed to ship it all to Vietnam or some other place where you can hire legal slaves, then fire all your countrymen and take their pensions

    2. Gravis misses two points.
      In the past, in west Japan, making Yakisugi was one of many tasks of carpenters, like cutting and nailing. It was not particularly painful, although some techniques and experience were required.
      Now, since many decades ago, factory made Yakisugi is available.

  4. People will pay to have things be “hand-made” so they can feel being special.

    I’m stereotyping, but I feel the people that are asking for Yakisugi are probably dilettantes who will paint it over in a few years over a trend on TikTok shows up.

  5. Oh I didn’t know this was a technique.

    On all my wooden hand tools, I take a big burner and burn the wood, exposing the layers. Not as roughly as this, but still. It burns the fibers that are sticking out. I then sand down the wood a little bit and repeat it a few times. I then apply several layers of boiled linseed oil. I end up with a handle that’s very smooth to the touch, but isn’t slippery. Feels nice, it feels natural and it looks stunning.

    1. Shou sugi ban is the term to look for on YouTube, it’s fairly easy to do. Bigger flames are better, I found that using a small flame it’s hard to get an even looking finish across the entire surface.

      The head of our makerspace asked me to mount a board on the side of a concrete wall to hold an electronic latch, and I decided to make it into an art project.

      I burned and brushed the wood surface, then glued two barrier tags (a’la Naruto) to each end
      since the makerspace is shared with the middle school shop. I figured they would appreciate it.

      It made a beautiful surface finish.

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