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TAFFY
5th June 1999, 06:54 PM
Hi This is my first look at this new site, I would like to hear from fellow wood turners on their experiences with Microwave drying of turned/unturned wood, I have done this myself and have had some success but having seen some of the videos and articles on the subject I feel that there is a lot more to learn.
replies welcome
Taffy

Neil Ellis
5th June 1999, 07:57 PM
Hi Taffy
One of the latest theories about Microwave drying is: Don't do it!!! It seems that after a few years the internal structure of the timber collapses, thus badly degrading the finished article.

This apparent problem has been known and talked about for at least a couple of years now. It is possible that the problem only comes about if the methods used are incorrect, but who is to say what is correct and what is not in the slightly hit and miss world of microwaving.

One of the most favoured and apparently safest ways of drying and stabalising green timber at the moment is by freezing the work, and from what I have seen of it, this method appears to be probably the best answer to the problem yet. (I am not talking about freezing logs, but the individual items after they are turned, before final turning & finishing.)

Vic Wood has an information sheet that he has done up on this drying method. I am sure he would be glad to share it with you. However he is in the USA conducting seminars and the like until early June.

Hope this has been of some help to you. I'm sure there are others who can jump in on this subject with some more answers and information.
Neil Ellis http://ubb.ubeaut.com.au/ubb/smile.gif

[This message has been edited by Neil Ellis (edited 05 June 1999).]

Marshall Gorrow
6th June 1999, 05:19 PM
I have microwaved rough turned bowls off and on for a couple of years. I have never seen ill effects from the process. The bound moisture doesn't escape unless somehow the cell walls are fractured. Natural seasoning, wether air or freeing causes some fracturing of cell walls. Boiling is also used but that can effect color a well. Probably the best thing is just to wait 3 to 4 months after rough turning. However, sometimes we are impatient. When I do use the microwave, (1) I always start on defrost fr no more than 2 minutes. (2) Let the piece cool at least 20 to 30 minutes before cycling again. I leave it in the microwave. Some put the piece in a paper bag. Ypou don't want the heated bowl to dry too quickly. (3) When it's cool too touch, it's ready to cycle again.(4) after 4 or 5 cycles I some times use the higher settings, although most will advise you to stay with defrost. (5) You can weigh the bowl each and every time. When it know longer loses weight, it is dry. When it is no longer damp to touch it is also dry. I'm sure that the structural integrety will not cause the bowl to collapse prematurally. There may be some mircoscopic differences but probably not as bad as the checks one can get if you let heat build up when sanding. The microwave is also an effective way to eliminate powder post beatles and other little critters that sometimes infest wood.It's not the heat that kill the bugs but the rapid vibrations of the cells in the wood. I'm not saying that there is no measurable change to the stucture of the wood. I just don't think it will effect the usefulness of decorative turned object. If that the case we had better all quit using spaulted stock. There is absolutely no question that the structural integrity of spaulted wood is compromised. This is just my opinion; everyone has a right to disagree.

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Marshall Gorrow
May your next turning be your best!

TASSY
7th June 1999, 09:39 PM
I tried this once and set fire to the piece
and have been too scared to try again
it took months to get the smell out of the microwave

Terry
8th June 1999, 09:59 AM
Re- Microwaving
Try this site it may help.
http://homepages.ihug.co.nz/~rhaslip/microwav.htm

TAFFY
9th June 1999, 09:52 PM
Well, My first qenquiry of others experiences seems to have generated an accross the board response.For those who may be interested I have done a bit of it over the last few years and the process I have come up with is this . First rule: Never boil the sap. I put the micro on high for 2 minutes and remove the piece for at least 10 or until it stops steaming. I repeat this process for as many times as is necesary and then cool the temp down to warm for the last few periods. if the piece is left in the oven on the last try then it will cool slowly and should not crack ( most of the time). I have written down the weights at each time and the length of time it was cooked and left to cool. The end result was a bowl of around 8" was put into the micro 12 times and then left overnight to cool and dry.
You can't rush nature!!
try it Tassy Faint heart and all that.

Taffy

Chris Longworth
11th June 1999, 12:17 AM
Dear Taffy,
Thank you for raising this topic of conversation. Only once before have I tried microwaving a piece of my work, which was a great disaster. This led me to read with great interest the replies you have received. I visited the homepage Terry mentioned in his reply and have just finished microwaving a very wet piece of camphor laurel I have turned into a bowl, with great success, and no smell in the microwave. See what you think Taffy, I will definitely be using this technique more often. Regards, Chris

[This message has been edited by Chris Longworth (edited 10 June 1999).]

jacschnell
11th June 1999, 12:40 PM
I have been microwave drying for about 3 years, mostly on goblets and small boxes. I agree with Marshall Gorrow on starting with defrost and letting the piece cool (completly) between zappings. I did burn one piece (internally) early on but I soon learned (wife won't let me use kitchen microwave)I had to buy a small unit at a garage sale (all of US$20. The pieces did not distort as much as similiar pieces with normal drying in brown bags.

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Jack Schnell

Keith Thurgood
13th June 1999, 09:14 AM
I have had a few smiles to myself while reading the answers re. micro-drying . I too have been barred from using the kitchen " micro ". I now have a unit in the shed & at times SAP a piece but I have found " THE FRIDGE " (even though a little slower ) gives me far better results." THE FRIDGE " has 2 light globes ( 60wt) set on the floor of the unit & a container of water to keep the humidity up , ( 27 ) . The temp is kept at around 30 c with the help of a thermostat switch. ( pinched from an egg incubator )I partly turn or carve a burl then place it in " THE FRIDGE " the time varies from one piece to another but within a short time you will find wot works for your work .If you are not working with burls make sure you keep the water up to it , as the humidity is very important to stop checks & cracks . ( Not a big problem with burls ) You MUST drill holes around the unit , up near the top to allow the escape of some of the heat & moist.
I hope this give you some food for thought , It works that well for me I'm going to cut the back out of two fridges & double my drying space !! Still only one set of controlls .Dont hesitate ,if you have any problems just ask !
Hope this will be some help .
Keith thurgood
( EXPOSED GRAIN )