Texian said:
Bill,
Sounds like, the more gentle the process, the better. Even if it takes a couple or three days (sealed in plastic between sessions), is better than weeks or months when successful. Have a couple small pieces of oak developing small cracks while drying after alcohol soaking and wrapping in paper. I understand that oak is a problem child, but it was worth a try. Have a spare m'wave oven in the barn, and will attempt the process.
All drying methods are are based on the same thing, controlling loss from the exterior to a rate which can be replaced from the interior until an equilibrium is reached. Joy of microwaving is that it moves water from the center outward much faster than plain air drying, because even bound molecules escape faster with increased energy. Like all good things, however, it comes with a price tag.
Two large cautions on oak, which, given your location, is likely to be one of the many "red" oak varieties. First, every ray fleck you see is a potential fracture line. It is a structure built to transfer moisture radially more rapidly than simple cell to cell diffusion, and is structurally unsound. If you have a great rate of curvature, such as a small diameter piece or tight curve on a larger, your chances of saving are greatly reduced. Sharp edges are out for the same reason.
Second, it's going to smell terrible. You mentioned the barn. It will develop somewhat the same odor. Don't use any microwave the wife may use in any place she might drop in. Ask the man who
once dried elm in the kitchen, and purchased a new micro for the wife.
With the microwave it is actually important to get the piece close to uniform in thickness. You hear it often when applied to air drying, where it applies but little, but in this case a lot of wood around a spot provides insulation which can allow heat to build up and ignite the interior. Dense areas like knots, which are generally drier than the rest of the wood anyway, are another potential trouble source. So calculate your anticipated shrinkage from the tangential/radial tables, and use only a modest fudge factor to determine your wall thickness if you're planning to turn/dry/turn (TDT), so you can dry it rapidly and not ignite. I consider micro drying more suitable to non-TDT pieces, where warp is of no consequence.
Can't say I've ever observed it, but my microwave says not to use color paper towels or brown paper because of the risk of ignition. Might be something to think about. I used vegetable bags where they would fit the pieces. They are micro perforated to preserve high, but not dewpoint high moisture around the vegetables. Plastic with a few larger holes works well. Longer times on lower settings versus high and short for me.
Almost forgot. Do yourself a big favor and spin the daylights out of the piece to get as much unbound moisture as possible out before you begin the process. That way you'll speed things up and minimize evolved water stains.
