Drying wood with Silica gel

Some time back a woodturning friend had a brainwave when his wife bought some silica gel (which is, in fact, in bead form) for drying flowers. He thought if it could dry flowers, why not wood? He presented the idea to the guild, citing a couple of small plates as examples of the success he had achieved.  When I dry wood for re-turning or to completion I use both the “shelf” method and the microwave (I have my very own :)) depending on my need for speed and of course size. Mostly I use the microwave for hollowforms and tubes while large bowls and platters get the “bag and switch” treatment if they are of any size. My issue with the latter is that I am not that disciplined that I monitor things religiously enough over long periods. The microwave on the other hand  can be a bit too aggresive requiring each piece to be monitored carefully during the process. The silica gel seems to be in between the two methods so adding it to my arsenal seemed like a good idea.  

Silica Gell sold by Lee Valley

I purchased a small jug of gel from the Lee Valley Tools gardening catalogue. Lee Valley’s gardening section – to me at least – goes completely un-noticed. I did not inherit my mother’s green thumb nor her love of mucking around in the garden. Nor was she able to instill any horticultural desires through endless hours of forced weeding; I preferred my father’s shop.  But I digress. The gel is available in 2 Kg. containers for about $20+ dollars, as I recall. The instructions include three methods of use: “air” drying, oven drying and microwave drying. Basically, the air method takes 5 or more days, the oven method requires a few hours and the microwave even less. The air dry method is much faster than traditional “shelving” methods, the microwave method adds a greater element of control and the oven method is – to me at least – a new tool completely. All three require a container to hold both the piece and the gel, so obviously it needs to be compatible with said shelf, oven or  microwave.  A word of advice: although various kitchen bowls might be ideal from your perspective, that view will probably not be shared by all in the household. Like the  microwave – you may have to get your own :(. The piece must be completely covered so the container should be just large enough to accept the piece and of course you must have enough gel to cover the piece: you may have to buy more than one jug. 

My first venture was with a small hollowform turned from green, spalting Arbutus turned to about 1/2″ wall thickness with a fairly large lump of wood where it had been chucked. It was a shot in the dark because the wood was quite spalted. I kept it in the material for 5 days as per the instructions (for drying flowers). It had lost all its weight in water because reburying it for another few days caused no additional change in weight. There was about the same change in dimension as I would have expected in any other drying method but unfortunately there was a crack through the large chucking mass which could be expected (it dried slower than the thinner portion).  The only thing left was to reconstitute the gel by drying in the oven. All in all, not a bad first experiment considering the short drying time.  

Next effort I will fill the vessel with silica gel but also bury any portions that have a heavier cross section so that water is pulled from that portion at about the same rate as the thin portion. Hopefully drying in this way may not cause the uneven shrinkage.  

As always, I encourage your comments and questions, so please refer to the tag line at the bottom of the article to post a comment.  

 

About Ed Pretty

I am a professional woodturner, specializing in gallery work, commercial work, teaching and demonstrating. I have been turning since 1958, so... a long time. I use this site to present my work to the public at large and to let people know that I am available for teaching private lessons in woodturning. Wood turning is one of my passions (the other is motorcycle touring). It is my desire to pass on everything that I have learned over the years to others so that the craft of woodturning will grow.
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