Microwaving Wood

================================= Yes, the microwave can be used to dry wood. The way most that I know about do it in stages. First, if you have a scale, weigh the piece before you start. Then put the piece in the oven and cook on high for 2-3 minutes. Feel of the piece. If it hot or very warm, remove it and allow it to cool to room temp. Then weigh the piece again. The time will vary from one oven to another (600 watts or 1000?), and some woods will heat faster than others due to density and moisture inside as well as oven power, so you will have to experiment for different species and sizes. Repeat the above procedurs until the piece no longer shows a weight loss after the cycle. Then the piece should be at equilibrium moisture content. Don't over do it!

Ken Moon Weberville, TX

Erwin,

You would be well served to search the archives on this procedure.

take you there. There are a number of similar ways to do it,NONE of which involve heating the piece on high, though! That is thequickest way to destroy the wood. The whole point is to acceleratethe process, but not to accelerate it too much, otherwise the woodwill just warp and crack all to pieces. Please do look in the archives because this has been coveredexhaustively. Here is a quote from a reply I posted almost 2 yearsago on the subject:

------- "I've done this to a limited degree, but only with turned or rough-turned pieces. A guy in my turning club microwaves his blanks, and claims to have very good success at it. Regardless of whether you do them whole or rough-turned (which seems the most sensible to me) the procedure is the same.

There are three basic methodologies to determine the "done-ness" of your wood.

First is the pin-type moisture meter. With it, you can directly test the moisture content of the wood, as you microwave, until you reach the desired level of dryness.

Most people don't have one, so the next best method is by weighing. First weigh your blank and record it. Then, about every three cycles, weigh it again, after cooling. When it stops losing weight, it's as dry as it's going to get.

Third, guess. I've done this on a number of dried pieces that I wanted to crack and warp anyhow, and I just wanted them dry, so I could finish them. Just keep cycling the thing through the microwave, and stop when it feels dry. If it's no longer noticeably cool to the touch when it cools of from microwaving, then it's pretty close to dry. Again, not exact, but works in a pinch.

Now, for the microwaving bit. There are two different approaches to this. One, you put the thing in a plastic bag with a wad of paper towels, removing it from the bag after the cycle, and either drying or replacing the paper towels. The method I use is to just put the piece in the microwave on a paper plate, so you don't get sap baked on to the turntable.

Set the microwave at about 20% power. I would say even less if it is over a 2000 watt unit. Microwave for about two minutes and let cool completely, (usually about 1/2 hour). I generally do this while I'm doing something else, so the wait times don't really bother me much.

As the piece gets drier, you might want to reduce the nuking time from

2 minutes down to 1.5 or even 1 minute, depending on how thin the piece is, and how hot it is getting. Heat is the enemy of drying wood. Too little and it won't dry this month, two much and it will definitely crack and warp. The whole thing is, to keep it getting warm, but keep it from getting --hot--. As the piece gets drier, the cool-down time becomes more important, because it will get hotter with each cycle.

Success or failure in microwave drying is dependent on many things, and I think it is still in the stage of development where it could be considered "experimental," since no guidebook, that I'm aware of, has been published on the topic. I would see the one, key thing to not violate would be to give in to the urge to speed things up a bit by leaving it in for a bit longer or turning the power a bit higher. You'll only ruin the piece and have to start over again. If you want it to go faster, rough turn the bowl and go from there. You'll be drying a lot less wood.

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-- Chuck *#:^) chaz3913(AT)yahoo(DOT)com Anti-spam sig: please remove "NO SPAM" from e-mail address to reply. <

September 11, 2001 - Never Forget

The Glad folks make a vegetable bag with perforations which makes a great microwave aid.

I'm a low power and longer time person myself, and the bag obligingly retains humidity until you remove the piece and reverse the bag. Repeat cycles and reversals after cooling until the bag no longer gets soaked.

Warning - it will muddy the figure of the wood if you steam it.

Thanks to all who have contributed information. I no doubt should be checking this news group more often. If I would have done that I would not have all of you repeating what already has be hashed over in the past. Again , thanks and now to the microwave.

Note that there are really no power levels on a microwave. Medium power means the power is on full half the time. Full power is all the time and low power is 20% of the time. You can hear the tube cycle on and off at the lower powers. Medium power is like using high power for 30 sec out of a minute. The water (or steam) then has a chance to move to the surface and escape. But the magnetron tube only operates at one power level. Greg