bowl rough-out drying question

[Ted Evans]

Hi all, I have an upright freezer that I converted into a kiln for drying my rough turned projects, starting with 40w, 60w and 75w bulbs. My question is, when the wood is maple, walnut and cherry, end grain both inside and out plus the rim, has been coated with anchor seal, should the items be allowed to drop from 32 plus MC down to a lower MC before placing them in the kiln or, can one put them in while the MC is still high? Any thoughts and/or suggestions would be appreciated. Ted

[Chris Studley]

I'm no expert (or even novice) regarding the drying of wood.

That said, what comes to mind for me is... What happens to the other pieces in the kiln when you place a wet piece in there? I would imagine that it would change the environment, RH, for all of the pieces in the kiln, kind of like placing something hot in the refridgerator, it brings up the temp of the gallon of milk sitting next to it.

Obviously the RH changes everytime you place a new piece in the kiln, but I'd imagine the more wet of a piece you put in the more it effects the drying rate of everything in the kiln.

[Russell Neyman]

Hi all, I have an upright freezer that I converted into a kiln for drying my rough turned projects, starting with 40w, 60w and 75w bulbs. Ted

I assume you have some sort of temperature gauge, and you track that. The converted refrigerator/freezers I've seen use one light bulb, with an adjustable opening to control the internal temperature, opening it to lower it, and close it to raise it. I'm no expert, but from what I've heard a kiln of this type should be kept between 75 and 100 degreees, and my friend keeps his about 85.

[Jamie Donaldson]

The function of a kiln is to lower the moisture content in a controlled environment, so put the rough-outs in immediately. If wood is allowed to partially air dry you run a greater chance of checking, and the humidity and temp in the kiln must be modulated to avoid rapid changes. If the air in the kiln is not vented in a controlled manner you will have a mushroom farm when you open the door.

[Steve Kubien]

Throw 'em in right away, and ignore moisture content. Seriously. There are easier ways to do this. I blogged about it in March of 2011.

http://greenleafwoodstudio.com/2011/03/building-and-using-a-homemade-wood-kiln/

[Ted Evans]

Thanks to all for your comments and thanks Steve for the link to your article on the subject, I found it to be very informative. Some time back, I convinced my wife that the old freezer was too hard on her to defrost it and that she really deserved a frost-free one. So I had to do something with the old. I drilled a half dozen or so holes in the top and bottom and mounted a light bulb fixture in the bottom. I have dried quite a few peieces of spalted maple with great success. Some walnut did ok, some not so good and the same with cherry. I did leave them set in the basement until the MC had dropped to about 20% or so before placing them into the kiln. This time I am going to put them in as soon as the Anchor Seal dries.

Some walnut bowl blanks.

230827

The bottom with the light bulb.

230828

This is the remote Temp/hum transmitter inside the freezer.

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And this is the receiving unit outside of the freezer. This setup allows me to read the temp/humidity without having to open the door. Looks like it is time to change the battery.

230833

The MC is checked and written on three locations on the bowl before placing them into the kiln and then periodically checked until it drops to 10% or less. The wood in my shop measures from about 8 to 10%, occasionally a little higher. I am hoping that the suggestion to promptly put items into the kiln will reduce some of the cracking that I have experienced. Thanks again for your comments.

[Steve Kubien]

I take my pieces out every couple do days and weigh them so I know how much weight (moisture) they are losing. When I do this, I carefully look for any checks that have started to develop. These get a dose of thin CA and the accelerator. Knots get CA'd before I even use the anchor seal.

I have probably it 200 bowls of various sizes through my kiln and I have only lost 1 because it checked bad enough to become firewood.

[Ted Evans]

I take my pieces out every couple do days and weigh them so I know how much weight (moisture) they are losing. When I do this, I carefully look for any checks that have started to develop. These get a dose of thin CA and the accelerator. Knots get CA'd before I even use the anchor seal.

I have probably it 200 bowls of various sizes through my kiln and I have only lost 1 because it checked bad enough to become firewood.

Thanks for the tip on looking for checks, that is something that I have not done as I have not been paying much attention to individual bowls until I thought they were getting close to the 10% figure. Sounds like a good idea to me, I appreciate the info.