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Drying wood blanks in the microwave? (Read 474 times)
 
Mark Putnam
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Drying wood blanks in the microwave?
May 26th, 2016 at 10:32am
 
The saga continues!

In my quest to (a) harvest free wood for turning and (b) dry that wood as quickly as possible, it has been suggested that I try drying harvested wood in a microwave.

Does anyone do this effectively? If this topic has been covered previously, can you point me to previous posts in order to duplicate effort?

Thanks for your time.
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Tom Coghill
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Re: Drying wood blanks in the microwave?
Reply #1 - May 26th, 2016 at 10:55am
 
Mark,

It has been discussed, but others are better at bringing up those discussions...

What I have found is that for the birch trees found here, the heat generated within the rough turned bowl during the microwaving process can cause the wood to change color  (See photo).

My suggestion is to go at it slow - Microwave for 15 - 20 seconds then let it stand for 10 minutes or so... then zap it again and let the heat dissipate again till cool. 

I found that I can take a very green 8 inch blank, rough turn it, process it thru the microwave and complete the final turning in a weekend.  I find that it will still move slightly afterward (in the weeks to follow), however usually not very much.

Good Luck and take it slow (especially if you are using your kitchen microwave and not a shop microwave)

Tom
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Chris Gunsolley
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Does wood lose color as it dries, regardless of method?
Reply #2 - May 26th, 2016 at 11:03am
 
Tom Coghill wrote on May 26th, 2016 at 10:55am:
What I have found is that for the birch trees found here, the heat generated within the rough turned bowl during the microwaving process can cause the wood to change color  (See photo).


Apparently, people note that the wood tends to lose color whether you microwave the bowl to speed up drying, or whether you boil it in water. Also, wood with moisture in it simply has more color. Which gets me to wondering, does wood simply lose color as it dries?

In other words, perhaps it's not the method, but the mere fact that it's drying that makes it lose color, and this will inevitably occur?

If you were to compare the same bowl after it was turned green, to that same exact bowl after it had sat drying in the conventional method a year later, would you see a color change? If not, what exactly would allow the wood to retain its color in a slower drying method, as opposed to a faster drying method?

To me, this all makes sense if you simply attribute the loss of color to a loss of moisture content in the wood...

One factor that is not accounted for in this assumption is the potential influence of heat on the color of the wood. The heat is applied on both boiling and microwave methods, but not in a slower drying method...
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« Last Edit: May 26th, 2016 at 11:05am by Chris Gunsolley »  
 
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Mark Putnam
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Re: Drying wood blanks in the microwave?
Reply #3 - May 26th, 2016 at 11:04am
 
Thanks, Tom. As it turns out we have a spare microwave that may now become the "shop microwave." So we should be good to go.

Do you cover the wood in anything (paper bag, etc.)? And do you run the microwave on High or some other setting?
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robo_hippy
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Re: Drying wood blanks in the microwave?
Reply #4 - May 26th, 2016 at 11:59am
 
If you haven't figured this one out, then never ever use the house hold microwave for this...... unless you live alone, and even then, not a good idea.

robo hippy
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Tom Coghill
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Re: Drying wood blanks in the microwave?
Reply #5 - May 26th, 2016 at 2:17pm
 
Mark,

Good - use the microwave in the shop (Robo+1).

I do not coat nor cover the wood (although putting it in a paper bag would have merit....).  Look at the photo.  The variations in color in that bowl I will not find in bowls that I don't microwave.  The "naturally" dried, are all the lighter color.  I have attached another photo of the same bowl showing more of the variation I mention.

I roughed this to about 3/4 inch thick, zapped over a period of 12 hours, and final turned to 3/8 inch thick and carved the outside to add variety and interest.  It was a bowl I donated to a charity for an auction.

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