Shou sugi ban cedar siding

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Shou sugi ban tests with 2 updates

Well. In this exciting post I turn perfectly good white cedar boards into crispy Shou sugi ban siding.

Shou sugi ban is the Japanese technique of burning cedar planks to make a long lasting maintenance free siding.

It’s a slow process though. As you can watch in this video.

For pictures and more

Playing with fire

First off, doing the shou sugi ban is fun. I watched quite a few “how to” videos online. Mostly by people doing it for the first time. It’s very interesting to get “updates” on some of these buildings. I’ve seen quite a few shou sugi ban sidings that mottle and look like … yuck.

Here’s the look I went for. Not super deep alligator skin. More like mild checking.

So when I did my boards I made sure I got them well charred. Not alligator hide deep as you can see done online. But, as you see here, crackling about 1/16th of an inch shallow. Its a really pretty surface.


I also was very lucky to find, about two years ago, some Tung oil at a garage sale. This is real tung oil from Circa 1850.

Comparing the Tung oil (top) treated with untreated.
Comparing the Tung oil (top) treated with untreated. You can see the treated board loses some crackling but attains a much more uniform and deeper black.
Two board test

I use the tung oil on two of the boards to see what would happen. The oil goes on easily and disappears fast. So I work on smaller and smaller areas quickly spreading the oil with a natural bristle paint brush.

Result! The boards come out super dark black. And you can touch them without any char coming off. As you can see below, you get a deep deep deep interstellar deep black. Sweet.

The treated wood can be handled or rubbed without marks.
The treated wood can be handled or rubbed without marks.
The untreated wood rubs off.
With the untreated wood, the charcoal rubs off.
And as you can see

Also you can see the treated wood is a more uniform black. It also doesn’t rub off. The unoiled wood is shinier and rubs off.

Tung oil is really expensive and the wood drinks it up. So I will look into cheaper alternatives. Perhaps experimenting with soya oil.

Update 1:

I have now done an experiment with Soya oil from the grocery store. I mixed in a little kerosene (what I had on hand) to help it spread better. The Soya oil gives the same deep uniform black. However it does not dry as quickly as the Tung oil. I have rested the test boards for a week and the oil is still soft. Patience grasshopper.

I am leaving the boards exposed face up to wind, sun and rain to speed up the durability test. So far so good.

The soya oil is 1/12th the cost of Tung oil, so here’s hoping that the oil eventually hardens.

Update 2:

The soya oil boards left out exposed to sun and rain did dry. About a month or two into the experiment they no longer felt sticky. Result.

Like the tung oil applied boards the char does not rub off. So I have tung oil applied, soya oil applied, and untreated boards — all now up on the chalet. The treated boards have been used for door and window trim. The untreated boards are being used as siding.

I will report back next year about how the various treatments fare. Should that be: compare where on the lair the wear remains fair?

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