thetyreman":c36fmnc6 said:
off topic but custard, do you know if pure tung oil can spontaneously combust?
Yes, it can. It cures in the same manner as boiled linseed oil through absorbing oxygen to form a solid. Careful disposal of rags used to apply and wipe off tung oil is required, just as similar care is necessary for disposing rags used to apply any kind of linseed oil - it's oily rags that spontaneously ignite, not the liquid in the can.
Generally, the best advice I can give is to carefully dispose of all rags used with any finish that contains drying oils, which therefore includes oil based varnishes (the ones that you clean application tools with white spirits, turps, etc), and varnish/oil/white spirits mixes and the like. There is less risk with varnish rag disposal than with pure curing oil finishes (linseed oils and tung oil), because the proportion of oil is smaller, but there's still some risk. Bunched up rags soaked in non-drying oils such as motor oil and mineral oil don't spontaneously ignite, so that sort of ignition is not one to worry about, although they'll burn very effectively if they're set alight either accidentally or on purpose.
I feel incumbent, now the subject's been broached, to suggest a few safe disposal methods for oil soaked rags, although this might be more information than you wanted and also teaching you to suck eggs. However, a friend of mine lost his whole workshop and business through exactly this cause, so I do think it's a subject worth outlining, even if you've heard it before - others may not have and were unaware of the risk until reading this:
*1. Chuck them in a lidded metal bucket, or better still a can with a self closing lid designed specifically for disposing of rags (starves the oxygen).
*2. Spread them out on a non-flammable floor, e.g., concrete, or hang them over the edge of a bench (both prevent heat build up) but you have to ensure they don't fold up in a breeze - weigh the corners down, or trap them in place.
*3. Submerge them in water for a day or two, then dispose (keeps oxygen away and naturally discourages fire).
*4. Burn them on purpose in a fire of some sort - you know they're burning, and you're in control of it (or should be), although even just a few sopping rags do burn for a very long time! Slainte.
