: Ive always taken others's word for it, that it will ignite. And Ive read of
: several shop fires caused by it. I suppose I could crumple up a rag in the
: wood stove, along with tinder, and check it in the morning to see if it
: went off. Did yours tend to simply ignite, or was there pressure inside
: it? Fire the stove can handle, but explosion is not a good idea...

Rags are porous, so don't see how there could possibly be any pressure buildup.

: I usually drape the rag over the top of the remaining oil, so I can re-use it
: the next day.

As long as it's spread out, it's not a hazard. I don't believe linseed oil gives off any flamable vapors. Spontaneous combustion is caused by heat from the oxidation of the oil (that's how it cures), which is trapped if the rag is wadded up. If the heat is allowed to escape, such as when the rag is spread open, it can never get hot enough to ignite.