Almost had a fire today...

The culprit was an old T shirt that I used to wipe my hands with, and maybe the bowls that I sanded out for the only show I do any more, maybe 150 bowls and walnut oil. It had been sitting in the shop for a month, on the lathe, and I set it outside yesterday to put in the trash. I set it on a black plastic bag of very dry shavings. It had a couple of folds in it. My guess is that the added heat from the black plastic bag and sun light were enough to trigger the combustion. My son was taking a smoke break and let me know. I have experimented a number of times with walnut soaked oil rage, even putting them in tight balls, on gravel, in direct sun, and hand no combustion. This time I was not experimenting... I will never do that one again...

robo hippy

I did an experiment several years ago with paper towels that had been soaked in linseed oil. The same thing can happen with tung oil and walnut oil as you know. Anyway ever since my experiment I put the oil soaked rags and paper towels spread out flat on the ground in the garden until they are completely dry. In the summer that's usually a couple days.

Wow!! :eek: Thanks for the warning!

Thanks for the heads up. Accidents happen but it sure helps to be careful. Though it can be messy I have an old coffee can with water in it and all my flamables go into that when done, then outside until they get to the burning barrel. I know not everyone can burn paper but we live in the country. Not sure what I‘ll do if we move. Think I’ve seen an industrial disposal container for combustibles.

I remember someone commenting that all of their shop rags went into the wood stove... Good place to store them. I have always taken proper care of the rags with oils that have hardeners in them. Still surprised that the walnut oil went off. I have had damp rags for months in the shop... Just summer sun and the black plastic. Might have to try it again in the drive way some summer solstice day...

robo hippy

Thanks for the warning. What is the correct way to prevent a fire? I usually spread my rags with poly or other volatile finishes out flat to dry in a non-sunny area, believing that, once they are dry, the danger is passed.

Try lighting one after they are dry, and see how fast they burn.

I think the 'official' way for a business to handle combustible rags is a bucket of water. Most of us place them on gravel or concrete which can not catch fire. On metal is good too. Mostly keep them flat, not wadded up. Any solvent based finish and/or 'heat treated finish that has chemical driers added are really dangerous. The untreated walnut, linseed, or tung oil finishes are very slow to dry and generally do build up any heat. The other rags dry out over night. Another solution is the fire place or wood stove.

robo hippy

Uh, I put them in a combustible rag container, problem solved.

I typically put the solvent and oil paper towels outside and not wadded up. That way, it would be difficult for them to ever reach the ignition point. I suspect that they dry out/cure quickly. Sometimes if I leave them in the shop, I put them into a metal container. But it is always somewhat of a concern.

Just as dangerous is dripping oils onto wood dust or shavings--my best friend set his new shop on fire this way. Two 48" exhaust fans kept it going out the back wall until a hose could be found--saved it yeah.

i always use nitrile gloves with finishes. I always ballup any rags or wipers that i am using and wrap them in the gloves as I am taking them off and one glove over the other. they are in there tight and the oxygen can't get to them. you need that to get them going.. i was taught to always spread them out and have also used buckets of water. always have respect for rags with any finish in them as it doesn't take much to set the off
ron

"Another solution is the fire place or wood stove". not really good for the environment. that and burning garbage in the fireplace or stove. the neighbours don't appreciate the smell either
ron

I spread my used rags out on gravel or hang them to dry on a metal ladder in the driveway. Once they are dry, usually overnight, I toss them in the trash.