Boiling Rough turned blanks

[Jim King]

We are currently testing various drying forms of rough turned boiled bowls. Here are the results of a group of rough turned peices 10 days after boiling. As you see on the graph we had a moisture content of 100% when cut until fresh rough turned. 10 days later all have dropped at the same time drasticly to 15 to 25% moisture content and seem to have stabilized. Dont ask my why but this is how it worked out. Not a one cracked. Now we will throw them into the lumber kiln for a week and get them down to 6% or less. We are doing this with other forms also but the process is much slower so when we get results we will publish them.

[Stu Ablett in Tokyo Japan]

That is really interesting Jim, please keep us informed, it is an alternative to the DNA route.

Cheers!

[Joe Tonich]

Man....be carefull boiling, nasty things could happen. I remember a guy at 'The Pond' who got scalded when a bowl swelled and it blew up on him. Lots of pain and suffering. Make sure you have an oversized pot......

[Ben Werner]

sounds cool, Keep the data coming
How long do you boil something for??

[Jim King]

We boil a minimum of 4 hours per rough turned inch thick and 8 hours is no problem. The good part is of course that the peices dry to ambient levels very fast and the unusual part is that when put into the kiln to get down to 6% the boiled blanks are fine and one year air dried non boiled blanks will crack. Why ?

[Michael Cody]

Jim - boiling has been fairly well documented and IMHO proved to be the best overall way to control drying rates and cracking on the majority of species found in wood turning. I believe what happens is boiling breaks down the cell walls and lignin in the wood, plus it forces the water out of the cells into the areas between them, and then it's all reabsorbed equally. This also relieves the stresses within the wood. Because the cell walls don't inhibit drying after being boiled and they are all equal, the wood drys very fast with little distortion and little if any cracking.

[Rob Bourgeois]

I believe what happens is boiling breaks down the cell walls and lignin in the wood, plus it forces the water out of the cells into the areas between them, and then it's all reabsorbed equally. This also relieves the stresses within the wood. Because the cell walls don't inhibit drying after being boiled and they are all equal, the wood drys very fast with little distortion and little if any cracking.

YEP. I worked for a chemical oceanographer and we would boill wood sample to get the lignin "mobile" so we can then get a profile from the wood on a mass spectrometer. There was a series of steps between boiling and getting a liquid for the mass spect using some nasty chemicals...

[Ben Werner]

when you say boil you mean just in plain old water right?? I've never done any of these drying procedures but I feel I should start.

[Dave Smith]

Thanks for posting the info Jim. Boiling is akin to steaming wood for bending. I believe the lignum is melted, for lack of a better term, when heating the wood thus relieving stress. When the wood cools the lignum solidifies. In the case of bent pieces in a form the solidified lignum maintains the new shape when the wood cools. It is not surprising to me that air dried bowls still crack in the kiln.

I have seen pictures of your boiling operation and I don't think you have to worry about a piece sealing off the vessel and resulting in a steam explosion when it is dislodged. For people boiling in small pots be mindful that a piece with little clearance around the side could swell and seal the pot. If that happens the water below the seal will pressurize and when the piece is dislodged a steam explosion can occur.

Jim is there any chance I could get a copy of your results in a database. I am willing to publish the information on my alcohol soaking blog if you want. In either case I would like to use the information in presentations that I do.

Dave Smith

Boil bubble, toil and trouble, mostly trouble in Longview, WA.

[John Shuk]

I have to wonder about boiling. With the cost of energy what it is right now, does this make economic sense. I personally am trying to do all I can to "avoid combustion" at this point.

[Ken Werner]

Hey Ben, I'm not sure your mother [aka SWMBO] will let you boil wood on her stove for 4 hours....
-dad

[Ben Werner]

yeah well.... I'll cross that barrier once I know how to do it

[Vaughn McMillan]

Hey Ben, I'm not sure your mother [aka SWMBO] will let you boil wood on her stove for 4 hours....
-dad

Sounds like a good off-season use for a turkey fryer.

- Vaughn

[Ken Werner]

Good luck. Maybe you can pick up a hot plate at a garage sale. Then you'll be stuck [er, your dad will be stuck] with a big 'lectric bill.

[Jim King]

Very happy to keep the data coming as fast as we develop it. Our business is wood so the more information we can develop and get out there the better it is for everyone.
We boil a minimum of 4 hours per inch of a rough turning and 8 hours will not hurt a thing, and yes just plain water.
I appreciate you guys responding as to why this is working. As much as I have talked about this on many sites no one until tonight has given a logical answer like I was inclined to believe.
Boiling is really quite economical unless you make soup out of your scraps. Just get an ugly pot or half barrel and put it in the barbeque pit. Not pretty but it works .
http://www.exoticwoodworld.com/index...tic&sc=process