Official Luthiers Forum!

Hi all.

I'm in the process of using tru-oil, and I've just been throwing the saturated rags that I'm applying with into the garbage beside my workbench.

I know that there are instances where these rags could spontaneously combust. In fact, that happened in my grade 7 wood shop years ago after hours. The janitor was luckily around to avert disaster.

What causes this? Does the varnish need to react with other chemicals/solvents? What precautions should I be taking?

Thanks.

Clint

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-Clint Beacock

Any thing saturated with a combustable solvent or fuel shoud be in a seperate metal can with an metal lid. never throw any solvent based compounds in your general trash collection.

Will do, Michael. Thanks

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-Clint Beacock

Oxidation. Finishes that cure by oxidation, such as for example, oil finishes with metallic dryers, can spontaneously combust in this way. The oxidation creates heat, and in an enclosed space they can get hot enough to start on fire. When I am finishing with something that has such a warning, I will have a bucket with some water to keep it in, until I can dispose of properly.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

It doesn't even need to be something that cures by chemical reaction. Just anything that reacts with oxygen could get hot under the right conditions. Anything that could combust when put in a flame potentially could generate enough heat just by reacting on its own with the oxygen in the air. Heat from sun through a window could also make the difference, which is what triggered a fire in an uncovered metal bin that I put out after hours in 11th grade machine shop (oily rags in a bin, with nothing else). This oil initially had some water in it, but the water evaporated. Any petroleum is not safe. Sawdust in a large pile can generate enough heat to ignite. All kinds of wet or dry chemicals could react. I don't believe the stories of people spontaneously combusting, however.