Heating wood in oil?

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Heating wood in oil?

Postby ericgoodson » Wed Aug 07, 2013 3:08 pm

Dan Dustin in the US treats his spoons by slow cooking them in warm oil, which he says drives out the water and forces in the oil. I just bought one of his spoons, and it has a lovely finish and feel. Hard yet welcoming to the touch. Does anyone have experience with this technique? How hot should you cook it? How long?
Also, has anyone tried baking an oiled spoon or bowl at a low temperature to speed the curing process?
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Re: Heating wood in oil?

Postby gavin » Wed Aug 07, 2013 4:06 pm

I have not tried this as I carve few spoons - but take a piece of scrap wood and treat it in various ways. Note the results. Take pictures. Report back!

There can be a tendency to spend hours in front of a screen and not enough on the tools - I know, I can do this myself!
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Re: Heating wood in oil?

Postby ToneWood » Wed Aug 07, 2013 8:42 pm

Interesting. I've heard of boiling bowls in water, steaming, baking, microwaving, and oiling but not heating in oil before - would that count as frying? :D Watch out for "chip pan fires".
Part of what you write makes sense to me, heating the oil is an interesting way of thinning the oil and allowing it to, perhaps, penetrate the wood more easily without chemical thinners. It might even help the oil dry more quickly (assuming a setting oil like linseed or walnut oil used) - although it might also break down the oil in an unusual way but I'm guessing you probably don't get it really frying, just a gentle warming.

As for driving out water, that sounds a little more dubious to me - frying tends to seal moisture into food, although it probably drives out some water near the surface. For a slim spoon I guess that might be enough. I would think it would be better to dry your wood first though, so that it soaks up the oil more readily. I'm just guessing though, I would be interested to read more about this though.

I thought Gavin baked (or microwaved) his chair/stool legs(?) to dry them out quickly - or perhaps I just imagined it! :D Drying very slowly has worked best for me so far, fast drying risks splitting as the outside usually dries much faster than the inside. I wondered about kiln dried wood but read something recently that suggested that wood kilns use steam.
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Re: Heating wood in oil?

Postby ericgoodson » Thu Aug 08, 2013 12:39 am

Thanks Gavin and Tonewood. 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.
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Re: Heating wood in oil?

Postby ToneWood » Thu Aug 08, 2013 7:32 am

Sounds like it might have been successful. :) BTW I wouldn't normally expect the oil to penetrate to the middle of the wood - just a little bit into the surface.
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Re: Heating wood in oil?

Postby gavin » Thu Aug 08, 2013 11:59 am

I should have asked this earlier: Why do you worry about getting the oil in beyond the surface? What is the merit of saturation? Just 'cos someone selling spoons does it as a point of product differentiation - why should you? Any oil will wear off in time, and even if saturated all the way thru at one time the oil will gradually leach out in use. Given the risks of fire and energy intensity and one extra item of slow cooker that you now must store for very occasional use - would you not be better to just smear the surface with some oil: raw linseed, olive, rape, groundut... ? Your finger makes a handy applicator! I quite like using inside of a walnut - much cheaper than walnut oil and delightfully low-tech.

Would you not be wiser to spend more time carving another spoon and less time decorating? As far as I can see - and do correct me if I am wrong - you undertake an un-needed activity here.
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Re: Heating wood in oil?

Postby bulldawg_65 » Thu Aug 08, 2013 4:20 pm

Dan Dustin isn't the only fellow that uses hot oil to oil his spoons. Many of us do. I have a crock pot filled with linseed oil that I soak my spoons in for a few hours at a time. The oil penetrates much deeper. Cures on the surface much higher. It isn't frying because the oil doesn't get hot enough. It needs to get to 375 degrees F to qualify as frying. The reason you want the oil deeper in the wood is self evident. When the oil polymerizes it adds strength to the spoon and makes it even more water proof.

Would you not be wiser to spend more time carving another spoon and less time decorating? As far as I can see - and do correct me if I am wrong - you undertake an un-needed activity here.


The reason for decorating is to make your piece more pleasing to the eye and to show a little bit of artistry in your work. Could the time be better spent making another spoon? Perhaps, but artistry is the difference between being a craftsman and a mere producer. To put it in another way. Why are there so many designs for chairs? I mean a simple four legged stool does the job, so why make one with spindles or arm rests or backs even?
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Re: Heating wood in oil?

Postby gavin » Thu Aug 08, 2013 10:10 pm

bulldawg_65 wrote: The reason you want the oil deeper in the wood is self evident.

I am sorry. I don't get this. Can you pls add to my understanding and explain why it is self-evident?

bulldawg_65 wrote: When the oil polymerizes it adds strength to the spoon and makes it even more water proof.

Are you suggesting that deep penetration is necessary to polymerise the oil? I know very little about this and am curious.
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Re: Heating wood in oil?

Postby gavin » Thu Aug 08, 2013 10:25 pm

bulldawg_65 wrote:The reason for decorating is to make your piece more pleasing to the eye and to show a little bit of artistry in your work. Could the time be better spent making another spoon? Perhaps, but artistry is the difference between being a craftsman and a mere producer. To put it in another way. Why are there so many designs for chairs? I mean a simple four legged stool does the job, so why make one with spindles or arm rests or backs even?


This is an interesting philosophical point. I believe a great deal of artistry can be shown off the knife and before decoration.
I submit that you can only be a craftsman once you have produced in volume, hence my suggestion you'd be better to carve another spoon.

bulldawg_65 wrote:To put it in another way. Why are there so many designs for chairs? I mean a simple four legged stool does the job, so why make one with spindles or arm rests or backs even?

There are different chair designs because various chairs have different applications: table, side, reading, desk etc. Chairs have backs because backs make them more comfortable. I don't think oiling a spoon alters its performance, only its aesthetic.

However well-decorated a Ford Edsel may be, it is still an Edsel. Even undecorated and filthy dirty, an E-type Jaguar is still appealing. If your spoons aren't glorious to look at and sweet to use before you decorate them, you fool yourself that decoration will help appearance or performance.
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Re: Heating wood in oil?

Postby ericgoodson » Thu Aug 08, 2013 11:32 pm

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.
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Re: Heating wood in oil?

Postby ericgoodson » Fri Aug 09, 2013 12:00 am

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). Here is a shot of my second bowl. Feedback appreciated.
image.jpg
my second bowl!
image.jpg (180.66 KiB) Viewed 6002 times
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Re: Heating wood in oil?

Postby gavin » Fri Aug 09, 2013 8:18 am

ericgoodson wrote: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). Here is a shot of my second bowl. Feedback appreciated.
image.jpg

Eric,
I salute your experimentation and prompt feedback. I have learned by it!

Re your bowl you want feedback on:
Will you
    1. take more images
    2. measure max rim diameter and height?
From that you can calculate aspect ratio and compare that ratio to other bowls that you like.
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Re: Heating wood in oil?

Postby ToneWood » Fri Aug 09, 2013 9:15 am

Result! Well done Eric - very interesting, I didn't expect the oil to penetrate so deeply. I agree with Gavin's point that you don't really need it to penetrate very deeply, we are just aiming to protect & seal the bowl/spoon & perhaps give it a glossy/oily sheen - but I see you point: if the oil penetrates completely & you scratch or bump the bowl, there would be no need to re-treat the surface, as the new surface is already oiled! A regular oil finish is quite resilient though, as there is always some penetration below the surface. When you mention beeswax, it makes even more sense because that normally needs to be warmed to make it usable* - I've used a warmed beeswax-linseed oil mix on a few items but I always give them several coats of oil first.

*I came across an old recipe for furniture polish which involved mixing/warming beeswax with white spirit (or might have been turps), to make a white cream that can be used cold. Haven't tried it though, prefer to avoid harsh chemicals.
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Re: Heating wood in oil?

Postby TonyH » Fri Aug 09, 2013 10:50 am

It would be interesting, as a sort of control, to see how far cold oil penetrated as well.

The use of hot oil to increase penetration when oiling tools (e.g., wooden planes) is something I have often heard recommended - of course this is with seasoned wood, so separate to any acceleration of drying.

For example: "Gransfors Bruks axe handles are soaked in hot linseed oil and dripped dry" - The Axe book, p6.

Does getting the wood well soaked with oil reduce seasonal movement by reducing water absorption ? Might cooking a bowl in oil reduce the distortion when drying by replacing the water with oil ? (In the back of my mind there's some dim memory of archeological methods of preserving old waterlogged wood)
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Re: Heating wood in oil?

Postby ericgoodson » Fri Aug 09, 2013 11:13 am

Gavin, thanks for the advice. Right now I am just sorting out the basics of making a bowl--getting a convex surface on the outside, figuring out how to make the base without "catching" and making a mess, leaving a smooth surface in general, rounding over the lip, avoiding tear-out, more gracefully removing the core, learning to sharpen my tools, etc... There is a lot to learn. Is there a place on this site where people who are geographically close can get in contact? I could use some instruction. Once I get things figured out a bit more, I will try copying bowls I like. I love Robin Wood's Porringer, and would like to buy one as a model.
ToneWood, again thanks for the feedback. I agree that, for a surface finish, you need worry only about the surface of the piece. I also agree about your beeswax point. Why use turpentine to drive something into wood when you can just use heat? Especially for items that come into food contact. I think what interests me is not what is happening on the surface, but underneath. If drying oil polymerizes and bonds chemically with the wood through oxidation, you are not just protecting the wood, you are changing it into a different substance, the result being stronger and more rigid (and noticeably heavier) than normal wood. I have soaked some spoons and kuksa's in oil for a few weeks, and after curing they do behave differently than wood that has been more quickly treated. They repel water better and seem stronger. I think this heating process might do the same without weeks of soaking, with the added benefit of pushing wax into the wood as well. We will see with time.
Thanks again to you both for your comments.
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