Home › Forums › Explore Media › Oil Painting › The Technical Forum › Walnut oil fire – is this story plausible?
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August 6, 2021 at 8:48 pm #1426741
Today I went to my favorite local art supply store to buy some supplies. I was speaking with the clerk about walnut oil and she said the owner decided not to carry it anymore because of the fire hazard. I reminded the clerk that we all know that all drying oils are a fire hazard because they dry by oxidizing, and that chemical reaction is exothermic, so oily rags or paper towels that are clumped together so the heat can’t escape can easily reach combustion temperature.
But she said that the owner had decided that walnut oil was especially dangerous because a friend of his used it on a new floor he was finishing and the floor burst into flames! Is this plausible? I think there’s got to be more to that story – either there was some other source of flame, or the “walnut oil” was some hardware-store wood-finishing product that combined walnut oil with some flammable solvent, or something. Walnut oil dries slightly slower than linseed oil, so if anything it should generate slightly less heat per unit time than linseed.
What do people here think?
August 7, 2021 at 1:00 am #1426751Walnut oil seems a slightly odd choice to use for this purpose, but what do I know.
A flat surface of drying oil should radiate the heat out of oxidation faster than the ignition point. Or paintings themselves would catch fire.
HOWEVER, maybe a wooden surface acting as a sponge could act in a similar way to a scrunched up rag. The depth of the wood taking up oxygen and building up heat faster than it could radiate it away?
One would think one would hear of more fires this way, but this is my first. Perhaps it requires a very open wood surface, plus a heated room, plus poor air flow.
insert pithy comment here.
August 7, 2021 at 9:19 am #1426820Anonymousa friend of his used it on a new floor he was finishing and the floor burst into flames!
We just can’t explain these things. but we do know that many people believe in lots of unbelievable stuff. I understand that human beings also burst into flames by the process of spontaneous human combustion. Now if we are composed of 90% water, (basically just cucumbers filled with anxiety), then they need to stop selling all of this hazardous bottled water, much less walnut oil.
August 7, 2021 at 1:09 pm #1426855I think it’s baloney! But, then I’m considered to be a cynic!
Linseed Oil dries faster than Walnut Oil, so it would seem logical, from mere common sense, that Walnut Oil (which dries slower than Linseed Oil) would present less of a fire hazard, that an oil that oxidizes more rapidly.
wfmartin. My Blog "Creative Realism"...
https://williamfmartin.blogspot.comAugust 7, 2021 at 5:59 pm #1426878<p style=”text-align: center;”>Don’t light a match after covering your floor with any combustible.</p>
August 9, 2021 at 1:24 am #1427111Then fire inspectors need to shut down supermarkets urgently. Many of them sell linseed and walnut oil (I mean those without additives, really drying), plus some carry high grade alcohol, and smaller items like fill ups for lighters. They are just asking for a trouble!
Ilya K
C&C always welcomeAugust 9, 2021 at 5:09 pm #1427239I had a walnut once that combusted spontaneously before I could eat it.
-- 'You just do it till you get it right'.
August 10, 2021 at 1:13 pm #1427375If such a thing actually happened, would we not have read about it in the news? I know that rags soaked in linseed oil can combust under certain circumstances — low air circulation, high ambient temperatures. But I’ve never heard of such a thing happening with walnut oil, which does not dry as rapidly.
August 10, 2021 at 5:17 pm #1427404If such a thing actually happened, would we not have read about it in the news? I know that rags soaked in linseed oil can combust under certain circumstances — low air circulation, high ambient temperatures. But I’ve never heard of such a thing happening with walnut oil, which does not dry as rapidly.
When the news reports of fires from “oil soaked rags” they don’t usually specify what sort of oil was involved. All drying oils are capable of spontaneous combustion if rolled up as wet rags or paper towels. The difference between walnut oil and linseed oil WRT drying time is fairly modest so all it would take to start a fire with walnut oil would be a slightly bigger ball of wet rags than with linseed oil. Graham, Utrecht, Blick, etc, all have warnings about this. Here’s the MSDS for one of Blick’s walnut oils . . . http://www.dick-blick.com/msds/DBH_SDS_010451002.pdf Don’t underestimate the dangers of improper disposal of walnut-oil rags or paper-towels.
The comment about grocery stores makes no sense – hardware stores and art supply stores have plenty of linseed oil on the shelf and they don’t burn down either, because a drying oil in a sealed container has no access to oxygen.
Which is also why it’s irrelevant to the original question since if a walnut-oil-treated floor exposed to air could spontaneously combust we’d also be seeing paintings drying on the wall combusting. So I don’t think the original story is plausible, but nothing to do with walnut oil – it would be equally implausible with linseed.
August 10, 2021 at 9:25 pm #1427428Anonymousthe owner had decided that walnut oil was especially dangerous
The rest of the entire world has not made such a decision. No, walnut oil is very decidedly not especially dangerous. Flash point is the temp where enough vapors are given off to be ignitable. The flash point is >215F. There is no way that the temp of that floor was hot enough to boil water, even if the walnut oil soaked into the wood and cured, dried, and polymerized. Walnut oil is not classified as a flammable material, flammable means that the material has a flash point of 100F or less. Walnut oil is well in the combustible range and can burn if heated over 320F. So no, walnut oil just will not ignite and burst into flames by simply applying it to a wood floor at normal ambient temperatures.
A couple of communication errors could have occurred here with the parties involved. The product may have just been a walnut colored finishing product, containing stain, solvents, and no actual walnut oil, or it may possibly have been a walnut oil based product, that was formulated with some walnut oil plus various sundry other highly volatile solvents that were flammable. If significant fumes were generated from a highly volatile solvent, and an ignition source was there, for instance, an older gas stove with a pilot light on near the bottom of the oven, or some other source of a spark, etc. , then the fumes from a volatile solvent could possibly be ignited, but not just neat walnut oil nor any vapors from walnut oil at normal temperatures. Another unlikely scenario would be if the home owner had left walnut oil soaked rags on the floor and they were all contained and bunched up, and then spontaneous combustion could have occurred.
August 11, 2021 at 12:57 am #1427440The comment about grocery stores makes no sense – hardware stores and art supply stores have plenty of linseed oil on the shelf and they don’t burn down either, because a drying oil in a sealed container has no access to oxygen.
You are taking my comments too seriously.
Ilya K
C&C always welcomeAugust 24, 2021 at 9:39 am #1430137OSHA requires us to make available a ton of SDS (Safety Data Sheets) regarding everything from hand soap to solvents, etc. I looked for walnut oil- Unrefined walnut oil has a smoke point (usually ref. for cooking) of 250-324° F, refined walnut oil – 400° F. Application techniques do vary, but I’ve never seen any application that brings walnut oil or similar oil much above 150° F.
Oxidizing chemistry presents a new monster into the equation. Strange and dangerous problems can quickly occur such as: if Chlorox 5% is used to clean wood before oiling, the residual chlorine can set off a fast oxidation and subsequent catastrophe. Another example is the making of gun-cotton, used back in 1700’s–1800’s, and it’s very explosive.
Anyway, the most suspect walnut oil situation would come from using an organic solvent with the oil to help it flow. Mix that with a liquid dryer and the stage is set for spontaneous combustion. But, walnut oil alone I would deem as safe, but store it in a metal enclosure.
Art Always Outlines the Artist
September 13, 2021 at 4:55 pm #1434858- Why would anyone use plain oil as a floor finish? It wouldn’t be durable enough to walk on.
- As for it bursting into flame, that’s not very likely, and probably impossible.
September 13, 2021 at 5:40 pm #1434862It’s the solvent in the oil that’s flammable. Drying oils such as linseed or walnut or tongue oils all cross link and provide a very durable finish. Multiple applications of these type oils become highly wear resistant.
Art Always Outlines the Artist
September 13, 2021 at 6:59 pm #1434873I spoke with the proprietor of the shop and he confirmed for me that the clerk who described the fire had it completely wrong, thus confirming my suggestion in the OP that it was not likely to be true.
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