# Linseed Oil et al ignition



## ahriman (May 25, 2020)

A question for the lumbering masses: I am making some baseboard heater covers out of some recovered cedar fencing. I know none of you have heard of this before, but I finish everything with BLO. As such, I am well aware of the combustibility of linseed oil and take precautions. I also know that linseed oil on furniture etc. does not combust because the heat is able to escape. However, linseed oil next to a heat source-I have a central boiler which runs 170* liquid through the baseboard elements for heating-is a new one for me to scratch my head about. I am inclined to say it is safe, but the more I think about it, the more unsure I get. My backup is Tung Oil. My backup backup is varnish.

Thoughts?


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## ahriman (May 25, 2020)

And BTW, the closest thread I could find to this topic is here ... until it got all derailed, or deoiled, or something. Feel free to point me to the info if it has already been well oiled.


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## Dark_Lightning (Nov 20, 2009)

If the covers are exposed to the air, you should not have a problem, even if heated by your heating system. They will just dry faster. It's when the rags are soaked and in a position (balled up) so that the catalytic reaction can build enough heat for ignition that a problem results. How are you dealing with the stench, in the meantime? BTW, it turns out that a lot of vegetable oils also spontaneously combust in the same kinds of conditions as linseed oil…which is something I only learned in the last couple of years. I had been taught (in the '60s) that only linseed oil would spontaneously combust. Live and learn!


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## ahriman (May 25, 2020)

> How are you dealing with the stench, in the meantime?


Are you talking about the sweet aroma of BLO? Love it, not stenchy to me


> BTW, it turns out that a lot of vegetable oils also spontaneously combust in the same kinds of conditions as linseed oil


Hope you did not find that out the hard way


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## SMP (Aug 29, 2018)

Can you just build and finish them in the garage or something, then install them after they have dried a few hours or overnight to be safe? Or at least don't turn on the boiler for a few hours so they can dry? I don't see the problem in hte summer?


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## PeteStaehling (May 3, 2015)

I never heard of wood finished with oil spontaneously combusting even if near a heat source. Does that happen? I have seen it happen many times with rags and canvas tarps mostly when they were exposed to sunlight.


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## wapakfred (Jul 29, 2011)

You are good to go if the odor doesn't bother you.


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## bondogaposis (Dec 18, 2011)

Linseed oil only spontaneously combusts from the heat of oxidation, once it is cured on a wood surface it is oxidized and will not be any more combustible than the wood itself.


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## Lazyman (Aug 8, 2014)

I sent an email to the Tried and True, who uses BLO on all of there finishing products, asking whether their varnish oil would stand up to heat for use on a trivet. The CS guy told me that the cured finish has a higher ignition point than wood so you should be fine. I tested it with a 450° point right out of the oven and there was not impact on the finish.


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## ahriman (May 25, 2020)

> I never heard of wood finished with oil spontaneously combusting even if near a heat source.


I have not either, but I am just a speck in this vast universe, and I have been talking myself into and out of this.

Thanx all for the comments. I promise to not watch any more alarmist YouTube videos before posting….


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## CaptainKlutz (Apr 23, 2014)

Wood starts to decompose and surface scorch when as the methanol alcohol and other components are released above 180-200°F. The thermal decomposition temperature of polymerized vegetable oil (like Linseed oil) is generally above 300°F, or higher than the temp required to scorch the wood.

If you want scientific proof look up the thermal decomposition data on polymerized vegetable oils. Challenge with linseed oil is that it rarely is used all alone to make a researched polymer. Can not quickly find you any free online references, but did find linseed oil thermal decomposition data in the research papers for Linoleum flooring polymers and some epoxy monomers. But the stuff is too complex for all but the chemist forum members to understand.

I.E. Don't worry about it. You will burn wood before the BLO finish.

Cheers!


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## Dark_Lightning (Nov 20, 2009)

> How are you dealing with the stench, in the meantime?
> 
> Are you talking about the sweet aroma of BLO? Love it, not stenchy to me
> 
> ...


No, sir, I read it here! And according to the Captain, the wood would ignite first. That makes sense, since the BLO is already oxidized when it is cured!


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## Jeff28078 (Aug 27, 2009)

The thing is once it's cured it's not BLO anymore. As mentioned several times it polymerizes. In other words it goes from a small molecule that can off gas and burn easily to a very large molecule that cannot off gas and doesn't burn easily. As long as you allow it to cure fully, no worries.
Having said that I know you said you like BLO as a finish but what's wrong with a water based polyurethane?


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## ahriman (May 25, 2020)

> what s wrong with a water based polyurethane?


Not a darn thing, why do you ask?


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## ahriman (May 25, 2020)

After all that, I ended up using Tung Oil.


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## theart (Nov 18, 2016)

Throw some on some scrap, take it outside, and hit it with a torch. I think you'll find that if the finish is dry to the touch it's not carrying enough solvent to ignite any more easily than raw wood.


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## ahriman (May 25, 2020)

> Throw some on some scrap, take it outside, and hit it with a torch. I think you ll find that if the finish is dry to the touch it s not carrying enough solvent to ignite any more easily than raw wood.


If nothing else, fun with blowtorches


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## SMP (Aug 29, 2018)

> After all that, I ended up using Tung Oil.
> 
> - ahriman


Same concept with basically any hardening oil. Just a conservation of energy equation is all.


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## ahriman (May 25, 2020)

You all are awesome, cannot thank you enough.


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## therealSteveN (Oct 29, 2016)

If it's liquid it has a flash point of 210 degrees F

Cured not so much. I think the wood will be more problematic. But if your heat source is only 170, then if there is an inch of spacing, I would sleep next to it, if it weren't for the terrible smell. 

http://www.kleanstrip.com/uploads/documents/KS_Boiled_Linseed_Oil_MSDS.pdf


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