Whenever doing wood finishing with linseed oil or solvent based products for example, or if you use oil stones to sharpen as I do, those oily rags and solvent stained cloths must never, never be left lying loose around the shop.
Always put them into a metal container with a metal lid such as a sealed refuse bin. Strange as it may seem to those who are not familiar with this, spontaneous combustion can occur igniting a dangerous fire.
Two years ago painters working in my town left a pile of linseed oil rags in a garage next to a house they had recently painted. You got it,..the rags later ignited and destroyed the garage and the house. The subsequent fire investigation proved this to be the cause.
Leaving solvent containers open in the work area is asking for trouble too. In a shop I worked in some years ago a stray spark from a grinding wheel from 30 feet away found it’s way into a tray of thinner and burst into flame. Fortunately we had an extinguisher at the ready and all was made safe.
Spontaneous combustion is usually thought of in terms of wet hay stacks or compost heaps igniting from the internal heat they generate. Oily solvent rags can perform a similar ignition in the right circumstances.
So always err on the side of caution and work safely.
Stay safe. Probably can’t hear it too often. I keep a metal bucket of water in the shop when I’m working with linseed oil or tung oil. Every rag gets tossed into the bucket as soon as I’m done using it.
Spontaneous combustion of oily rags nearly burned down a neighbor’s house this summer.
Next time I do laundry (Do NOT mix with the Missus’s clothes!) I take the bucket to the laundry room and toss the used rags in. Sometimes my clothes smell a little like linseed oil but I like the smell so what the heck!