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Sky Bluing About Taking Shou Sugi Ban to the Max...  RSS feed

 
pollinator
Posts: 2127
Location: Cincinnati, Ohio,Price Hill 45205
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We have seen Shou Sugi Ban  discussed here on Permies before.
Recently I have been investigating the Iwasaki-type high-speed charcoal kiln .
It makes high quality white charcoal quickly, and can be made with hand tools almost anywhere in the world.
It also produces and collects wood vinegar and at your option  tar.

This is actually the clearest most concise explanation I've found.

It consists of a conventional steel box wood stove vented into a steel "bell".
The bell is essentially a black oven for the wood.
The exist temperature of the exhaust is monitored, and during a particular temperature band, wood vinegar is collected via a simple condenser.
The steam before that point is allowed to escape, and the exhaust after that point is also.
The later exhaust is filled with tars, and could be burned, or collected.

The most obvious way to improve this device is to make the fire more efficient, but substituting a rocket stove for the conventional flame.

But currently my interest is this:
How far could one take the process of pyrolysis before we lose any useful structural qualities?

This paper PARTIAL PYROLYSIS of WOOD concludes that :
"A piece of dried wood cut with its long dimension parallel
to the grain of the wood will not change in length materially,
but it will shrink quite uniformly in cross section.
The modified wood from the treatment at 220-240° C. will be stronger
and have a higher apparent elastic limit but will be somewhat
more brittle than the original wood. It will have smaller
volume changes with changes in humidity. The modified
wood is brittle enough to be crushed rather readily to yield
a wood flour stable at 240° C., which may be incorporated
into molding compounds."


So, getting to my point, what if used these extreme heat treatments on large logs, and applied their own tars back onto them?

Using tar, from any source, is probably out of the question for many here.
Off the top of my head, I can't disagree.
We burn them in when we burn wood, but collecting them in one place is different.
Not a lot of oils
The destruction of of the woods structure may prove to be much.
And that paper was published March, 1943, so...
But if it worked  well, wouldn't that be neat?

Right now I'm imagining a very insulated tunnel of steel drums with a batch rocket stove or Tlud  venting into the middle.
A set of rails and a low sledge or cart, all steel ,would guide loads down a slight incline.
In one end and out the other, at least 4 drums long.
Large loads cranked along with winches, chocked into place and treated for hours?
Longer?
The insides of a log need treatment, that will take longer than a load of 2x4s.
A chimney near the exit, down low, maybe into a tee.
Wrap it in rockwool not for insulation , rather it could hold the water that the chimney is  cooled it with.
Probably needs a bypass from up higher on the bell.
Collect the wood vinegar, and burn the tar.
Douse the  feed stock when your temperature probe gets to 240 degrees C.

Foundation piers, fence posts, sculpture, artist charcoal, BBQ charcoal , biochar, roast pigs, or goats...


Worst case scenario, you have a giant oven.

Enough sky bluing, I would love to hear your thoughts on this madness!







 
master pollinator
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Location: Toronto, Ontario
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Interesting. I was thinking about this from a different perspective. I was looking at building a tool from an electric paint scraper or wood-burning kits that would char the surface of wood over which it was passed to a depth that would form a charred layer of protection, such that a structure could be built first, and then the exterior could be burnt in the same way that a finished wooden house is then painted.

I was also thinking about pyrolising wooden structural members in a high-temperature kiln that would keep them structurally sound. I don't know if that would work, but I am looking forward to the answer.

Good luck, and keep us posted.

-CK
 
pollinator
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Location: Boston, Massachusetts
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Chris Kott wrote:Interesting. I was thinking about this from a different perspective. I was looking at building a tool from an electric paint scraper or wood-burning kits that would char the surface of wood over which it was passed to a depth that would form a charred layer of protection, such that a structure could be built first, and then the exterior could be burnt in the same way that a finished wooden house is then painted.

I was also thinking about pyrolising wooden structural members in a high-temperature kiln that would keep them structurally sound. I don't know if that would work, but I am looking forward to the answer.

Good luck, and keep us posted.

-CK



Chris, regarding charring on a completed structure/building vs. treating the materials ahead of building... The investment in the construction is potentially at risk due to unintended fire. Cracks and gaps, and enclosed/hidden spaces could harbor embers that might go unnoticed for hours...
Treating in advance as single boards eliminates this risk can also be done at consistent, comfortable heights, horizontally, and even assembly-line style with low skilled help, versus at heights on ladders, working vertically (both low and high) as well as overhead.
There is also the opportunity to select materials based on their "final" appearance, especially for prominent locations, rather than luck-of-the-draw.

I found a link to an association working in these products: Thermowood

I'll do some more looking later, but at a glance, they state durability, stability as major attributes of the process.
 
William Bronson
pollinator
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Location: Cincinnati, Ohio,Price Hill 45205
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forest garden trees urban
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Thanks for finding this!
I'm working on my DIY kiln design, the existence of an industry is heartening.

Seems like these guys even have competition, as they mention other manufacturers using "the registered ThermoWood trademark".
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