Here's a Q&A from the most recent newsletter from professional woodworker David Marks. Hope this helps.
bobby g
Hi David,
I wanted find out how you dried the wood you use for turning. I am just starting to turn and wondered if there is any advantage to buying/building a small kiln, or if any of the alternate methods (alcohol, microwave, etc.) work any better or faster than air drying. I appreciate the time to answer.
Jim
DAVID'S ANSWER:
Hi Jim,
I read your email and I think the following article that is posted at my website should be helpful:
Alternative Ways To Dry Wood Turnings Green wood is wood that is freshly cut from the tree and still quite wet. The water and sap that is in the wood makes the fibers more flexible, enabling the turner to produce nice long shavings.
The downside to turning wet wood is having to wait long periods of time for the pieces to dry. The rule of thumb is to rough turn the piece to a wall thickness of ¾ inch to 1/ 2 inch and then put it in a brown paper bag for 6 months or until it reads eight to ten percent with a moisture meter. Here are three techniques that I have found to work well for the small shop without using a kiln. The microwave oven works surprisingly well to dry bowls with minimal cracking. I usually rough turn bowls or vessels to a wall thickness of ½ inch thick and then place them in the microwave and push the one minute cycle button. When you take the piece out it should feel warm to the touch. Let it set until it has completely cooled down. At this point I take a pen and put one mark on the bottom and then back in the microwave oven it goes for another one minute cycle. By the time I have 35 to 40 lines marked on the bottom; the bowl is dry and can be remounted on the lathe for final turning.
The second technique I like is boiling the wood. A lot of research has been done by wood turners worldwide and the general conclusion is that this technique works quite well on a variety of woods with minimal checking. One of the big advantages to this technique is that you can use it on large pieces of wood that are too big to fit into a microwave oven. I use a 50 gallon drum that contained vegetable oil and was free from a local food processing company. I cut off the lid and I use a propane stove designed to cook crabs as the heat source. Boil the wood for one hour per one inch of wall thickness. After removing it from the water, let it drip dry on a rack and then put a brown paper bag over it and let it set for a couple of months or until dry.
The third technique that I would like to share with you is alcohol drying. This technique is very straightforward and faster than the boiling technique. Rough turn the stock to a wall thickness between 1 inch to ½ inch. Place the bowl in a plastic garbage bag and fill it with enough denatured alcohol to completely submerge the piece. Let it soak for 24 hours to ensure good penetration. Remove the bowl and let it drip dry for an hour. Then cover it with a brown paper bag and set it on a rack making sure the bowl is upside down. You will find that small bowls with approximately ½ inch thick walls should dry in about 5 or 6 days and larger pieces with 1 inch thick walls should dry in about 10 days. The alcohol can be recycled and all three of these techniques have the added benefit of killing any beetles that might be in the wood. At the very least, if the alcohol doesn't kill the bugs, it will give them one heck of a hangover.