I’ve mentioned before that I use a light bulb kiln to cure the oil on my spoons and bowls. My old kiln got kicked around a bit during the move, so I decided to convert my old shop heater cover into a new kiln. You can get really fancy, but anything that holds some heat in will work. So, just a box with a porcelain light bulb fixture and a recycled electric cord and plug.
There are nine recently-finished spoons in there. I still have to take some photos, then I plan on posting them for sale Monday.
I used to use incandescent light bulbs. They are being quickly phased out. But I’ve found these reptile aquarium heating elements to work perfectly. You can find them many places easily, including pet stores. The come in different wattages and screw right into a light socket. My kiln is about 4 cubic feet of space, insulated somewhat. I find that the 75 watt element keeps the kiln at about 130 degrees Fahrenheit. According to what I’ve heard, wood can start to degrade over 140 degrees, so I keep it below that. And that’s plenty hot enough to decrease the curing time by at least 20x (for both linseed and tung oil). Of course, a kiln like this can also be used to dry chair rungs and things like that.
My new kiln doesn’t take up much space. It tucks into the corner of the shop where it does double duty as a stand, typically holding a bowl of dog treats and other stuff.
The doors are secured with a wooden toggle controlled by a simple handle on the outside.
Inside, the toggle is really a semicircle with a bit of a spiral shaved off one side to serve as a cam
When the handle moves up, the cam catches behind the top rail of the cabinet and pulls the door tightly closed. The rabbet holds the narrower door to its left closed.
And, this time, I got really fancy and dropped $25 on a digital temperature controller. These things are made for greenhouses, pets, and all sorts of uses. I plug it into the wall, then plug the kiln element cord into it. If the temperature gets over the max setting, then the power is cut to the element. Once the temperature gets below the minimum setting, the power kicks back on. There’s a cord with a temperature sensor that I’ve run through a little hole into the kiln. On the display above, it shows that the ideal temperature has been set to 130 F (+/- 3 degrees, thus the 133 and 127 numbers). The actual temperature is currently showing 129 F.
As it turns out, the combination of my box and the 75 watt element keeps the box at around 130 anyway, without the controller, but it’s still some peace of mind. With a little experimentation with different heating elements, you can manage the temperature without a control.
Or, this time of year, you can do as I often do and just let oiled bowls and spoons sit in the sun on a hot day. Just be sure to wipe off excess oil from the surface before it cures!
Dave – terrific idea since you make a lot of spoons. Would you ever use it for one of your bowls?
Thank you for sharing your processes and techniques!
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Yep, I do all the time, Skip. NOT to dry the bowl, but to cure the oil after the bowl is dry and finished.
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I love the little touches you added to the kiln Dave. The way the simple becomes elegant and full of presence. Thank you.
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nice job
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Thanks for that clarification. 🙂
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It’s surprising how hot old light bulbs can get. I have a similar setup for my kiln, and the controller gets moved over to a similar light bulb driven contraption that gets a pipe up to 330º for bending ukulele sides.
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Hi Dave. How can one tell is a spoon soaked in hardening oil is cured throughout?
thank you.
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One little test is to put the spoon in the sun. I find that if there is uncured oil, it will rise to the surface through the pores of the wood.
24-48 hours in the kiln is plenty in my experience. I’ve done some tests with thick paper towels that I’ve allowed different linseed oil samples (and tung oil) to wick through. At room temperature, It’s about a month before I don’t get oily residue on my fingers when handling a sample. In the kiln, it’s cured through in a day. It probably makes the most sense to do a few very thin coats, curing them in the kiln in between.
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Hi Dave, the spoons of course are gorgeous–
I have a box similar to yours we use as a sourdough rising box. I used the same sort of controller as yours. Hardest part of the project was getting the hardware store to sell me a 40 watt incandescent bulb. “No, I want to generate heat…”
Thank you-
John
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Good idea, John. My wife used the kiln for making yogurt or something a few years ago.
Makes me wonder what the Easy-Bake Oven folks have done about the lack of incandescent bulbs now?
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