Monday, December 2, 2013

"Firing" bowls and spoons in oil.

This summer I experimented with heating wood in oil, and posted a thread on the Bodgers site. Lots of dialogue in that thread, but here are the basics of my post.

I bought a $30 slow cooker/crockpot to do the heating. Blanks of various woods in various states of dryness have been submerged in flax oil and are happily warming now. I have it on the "low" setting, which seems to be about 275 degrees. After the first few hours the oil came to temp and moisture began to condense on the lid, which means some wetness is getting forced from the wood. I also saw lots of little bubbles coming from the ends of the wood as air escaped and oil entered. Now eight hours into the experiment and the bubbles have slowed considerably and no more moisture is condensing on the lid. I will unplug before bed and let cool overnight and see what it looks like in the morning. Of course I have been doing all of this outside, with fire extinguisher handy! :D Tomorrow I plan on cutting a few of the blanks in half to see how much penetration I got. I am curious to see if the oil reached the center of the blanks and if the moisture is still in the greenest pieces. I also wonder if the oil has penetrated to the center, if it has cured or if it will still be wet. If still wet, I will probably take some bits and put them in the oven at 225 degrees and bake them. Maybe I can force them to cure? Or maybe I can start an awful oil fire in my home. My wife should love that. More later.

Hi everyone,
So, some background info on where I got the idea from. Dan Dustin, in his little book "Spoon Tales", talks about a New England tradition of cooking axe handles in oil to harden them. He says he learned it from a blacksmith in New Hampshire named Norris Patch, who was a friend of his grandfather. Anyway, he writes that he raises "the temperature slowly over a period of about eight hours, then 'cook[s]' the spoons for about two hours at 213 degrees Fahrenheit in a mixture of about half beeswax and half walnut oil, boiling off the moisture and replacing it with wax and oil." When I spoke with him recently he said that he also soaks his wood in water for years before using. Not sure of all the other tricks he has learned over the last forty years of spoon making, but the results are really different than my spoons. His are heavier, stiffer, yet really fun to hold. Thanks to him for the idea. More on my results soon.

Hi again.
So, the results:
After "firing" the wood in oil and letting cool overnight, I cut each piece in half. All of them were fully saturated with oil. It penetrated right to the center. No wonder Dan's spoons are heaver than mine. They are truly full of oil. Once that oil polymerizes and hardens, the wood should be quite strong. No wonder artists have used linseed oil for centuries as a medium for oil paints!
Second, after "baking" pieces of the "fired" wood in the oven at 225F for 2 hrs, I found that very little oil left the wood. No real change in color or texture or weight. I will keep an eye on them over the next few days and see how the baked ones cure compared to the ones simply fired.
I will abstain from weighing in on the reasons for decorating crafts, though oiling does not seem like decoration to me. It seems like protection, allowing for a long, useful life for your spoon.
Next, I will "fire" one of my first bowls. I just built my first lathe a few weeks ago, and finished my third bowl today (along with running this experiment).

More (and more dramatic) results to report:
My eldest daughter was turning eight yesterday, and had been asking for her own special bowl like what Mommy and her sister have. So on Friday night I set about turning her a little kuksa out of relatively green maple. The wood cut wonderfully and even spun moisture out the ends during turning. Definitely green wood.
Emboldened by my recent experiments, on Saturday I put that new bowl into a mixture of linseed and beeswax, along with an older bowl that had already air dried. I cooked them both for eight hours and they reached a max temp of about 270F.
The results:
As you can see, cracks emerged in the end grain and the edge distorted pretty significantly in the green bowl. Live and learn. I will probably try to repair with epoxy.

Besides cracking the green wood, the oil/wax cooking also had an interesting impact on the dry bowl. Below is a shot of two bowls made from the same spalted birch. The one on the right has been simply soaked in oil for a few days. The one on the left was cooked in the oil/wax bath. It turned much darker than the other bowl, and did seem to warp more along the rim than the other.


  1. good day Eric, I went through your blog posts, and there is some great stuff, like this above here. Really like it… I'll keep following for sure!

    1. Thanks David. If you want to read the whole thread, check out the Bodgers site, ask and answer section, under the same title.