Oil and rags catching fire you tube video

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I wasn't aware of this self combustion of oilly rags until a couple of years ago, since then I've taken to either washing out the rags or using tissues and burning them when I'm done
 
I was doing a small job with osmo polyx oil and after only an hour a shop wipe was warm and smoking that was scrunched up with oil on.
Luckily i was in the room working and i always dispose of rags and wipes in a bin full of water after work…but i was surprised at the speed of this reaction
 
A scrunched up rag insulates the heat of reactions so it can reach ignition point. It is easy to avoid this problem. When you are finished open the rag and hang it over a convenient rail so the air can take the heat of polymerisation away. The reaction should be finished the next day when it can then be binned. I've done this when I use oil finishes and never had a problem.
Nigel
 
Its not just oil's, Fibreglass resins & particularly Peroxide catalyst are highly prone to spontaneous combustion.
At my first job at Thames marine's boat factory we had a fire one summer. Bins were usually old drums but there was a refuse strike so piles of GRP waste was stacked outside in cardboard boxes, It was lunchtime & most of the crew had gone to the canteen, I came up out of the cabin with my fibreglass brush & roller, I looked out of the door at the yard & nothing, turned & put the tools in the acetone, stripped my gloves off & looked back outside.
There was a 30ft high inferno, maybe 2 - 3 seconds?
I shouted "Fire!" at top of my lungs & started of the boat, Three others had just washed up & came out of the toilets, we all grabbed a fire extinguisher & went at it. The heat was terrific but fortunately we caught it just in time. Another minute & we would not have been able to stop it & the whole factory would have gone.
 
I think danish oil is also something to be aware of.
Any "curing" oil is an issue. Tung, linseed (boiled or not), etc.; or any finish containing them. The curing/hardening process produces heat (chemists say "exothermic"), and the oils are flammable. The fire triangle is heat/combustible/oxygen, and it seems like there's always some oxygen lying around. Spread the rags out - hang them from a clothesline, for instance - so that the heat dissipates or, as others have suggested, put the rags in a bucket of water, which cuts off the oxygen supply. The reason your furniture doesn't catch fire as the finish cures is that the film is thin and so spread out that, again, the heat dissipates.

Danish oil is an oil/varnish mix ("long oil varnish" in paint shop terminology), so, yes, it can be an issue.

Oily rags per se aren't necessarily an issue; if you've been working on your old sports car and have rags covered with motor oil, that's not so dangerous - well, the rags aren't anyway, no judgment made on the sports car - because motor oil is not a curing oil. That doesn't mean they're harmless or that you can leave them lying around. A rag soaked in motor oil is flammable, too, and an external source of flame, like a spark from a welding torch or a bench grinder, or an idiot with a cigarette, can catch them on fire. So best to put them in a covered metal container right away.
 
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Spread them out, or put them in a container with a close fitting lid. It's the half way house of a loose bundle open to the air which can get hot. Worse if the weather is warm.
 
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I invigilated exams and we were given a bag with all necessary accoutrements. In the bottom were loose spare batteries for clocks, calculators etc. ......... and mountains of paper clips. I pointed out to the lady in charge (a very intelligent person who had a first from Cambridge in about 1955) that this mixture was unwise (this was an unbelievably and unrealistically safety conscious environment) and she was quite surprised.
 
I knew about how Danish needed to be laid flat or washed after use but its just something you read on the tin, or are instructed briefly in, but 99/100 nothing is going to come from chucking the rag in the bin.

Until one of the big antique places(glorified junk shop) where makers, etc etc sell their wares or produce. I heard it burnt down, with everybody including us losing everything - 1xdining table in oak,2 coffee tables and 1x 4 door cabinet, all reduced to ash.

From what info from the fire brigade, they think it started in a cupboard where cleaning materials used for finishing were kept. And in that it kind of rammed it home the dangers were in fact real, and cloths needed proper care and disposal.
This is something i do now. All rags are gathered up and put in the sink, where i wash them through with water. Most oils you can wipe or squeegee on, and its normally paper towels to clean off the excess, so simply soaking them you're not really losing money or anything. Actual cloths are laid flat till dry, then washed on hot and soapy.
 
I am aware of the risk from fire fighting training and put my rags in a bucket of water. It was good to see that experiment and actually see the process in action. It also showed that a metal bin would be a safer option and give you a better chance of getting the thing outside before the plastic just adds fuel to the fire.
Regards
John
 
I find it interesting that the fire risk potential of polymerising oil soaked rags is something that seems to need to be relearnt or reminded about in the case of longer term users every few years, and that spontaneous ignition of such rags does happen with, in some cases, major losses, including potential loss of life.

I guess the warnings about this phenomenon printed on the containers is possibly forgotten, not seen, ignored, or not taken seriously by users. I remember using linseed oil at my furniture traineeship. Immediately after we'd finished the guy I was helping with the oiling job took the soaked rags and chucked them into the lit workshop wood burning stove. At the same time he warned about the fire risk and said something along the lines that by chucking them in the stove he knew for sure the rags were on fire, and that was the end of it, ha, ha. Slainte.
 
As others have said, I systematically burn those rags before the end
of the day. The knowledge that they cannot burn twice helps me to
sleep that night.
 
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