As boiled linseed oil dries, it absorbs oxygen and releases heat. The heat is negligible unless the rags are balled up. What happens is that the rags thicken and dry on the outside, making an enclosed container in which the warmth is trapped. The heat builds, the process becomes self feeding. The rags will first smolder, giving off an acrid smoke that smells exactly like an electrical fire. If you then pick up the rags, you should be careful because they can burst into flames the instant they get more oxygen (by the movement of air over the bundle). I would suggest scooping them up with a shovel, or a saucepan and lid.
If you refinish using boiled linseed oil, just hang the rags over something to dry. With normal air drying they do not heat up, do not spontaneously ignite. They simply harden as if varnished. At that point they are safe to discard.
Unboiled linseed oil is also available, but if you use it to finish wood it will not polymerise and will stay gooey.
If you want the boiled linseed oil to penetrate deeply, cut it half and half with mineral spirits on the first coat, then follow with a good rubbing in of straight linseed oil. Rub it on for each coat, the oil wants the heat and pressure to kick over properly and you'll be much happier with the look than if you just brush. Your handle will not ignite, nor will the open container. Just make sure to close the lid each time and you will be fine. Cleanup is with mineral spirits, and treat the cleanup rags the same way as the oily ones.
Hope all this is helpful!
Stephen
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Micah 6:8. Well worth the attempt!
