Boiling Wood

Boiling wood before drying has various effects on the outcome. May 23, 2011

Question
Does anyone have experience boiling wood before drying? I have heard it releases the internal tensions in burl and crotch woods so they not only dry better (less defect), but dry faster. I have heard this is the preferred process for madrone in the west.

Forum Responses
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
Boiling wood, which would also include steaming wood, has been researched. In fact, when using a preservative for treating, sometimes the wood is boiled in the preservative. The process is actually covered by a patent issued to Danny Elder a few years ago. When boiling wood or heating it to 212 F in a saturated atmosphere, the amount of moisture in the cell walls is reduced to about 22% MC (instead of 30% MC), so some shrinkage does occur. When the wood is brought out into the open after steaming, it immediately has a large amount of flash off of moisture. The process also seems to open up the wood so subsequently it dries faster.

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From contributor B:
I have an original volume of Audels Carpenters and Builders Guide, 1923. Lots of their advice is folksy and not necessarily laboratory tested. They say, "Boiling timber in water has much the same effect as steaming but is costly and probably weakening in its effect." (Vol. I, page 11.) It also talks about seasoning by immersion in water, salt or salt water, smoking, soaking for two weeks then air drying, boiling in oil (for wooden teeth for mortise gears), etc. Seems like they tried a little bit of everything back then.

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From contributor E:
Wood turners have been doing this for a long time. They will rough out a blank bowl/plate/etc, boil it, let it dry, finish turning it. It helps prevent cracking, etc.