S.H. does not generally occur until all the water or solvent has evaporated. The evaporation uses the energy given off in the self-heating reaction.
I am not aware of S.H. in SH, and would certainly be inclined to rule S. H. to ignition out if the SH is not close to dry.
John Lentini, CFI, D-ABC
Fire Investigation Consultant
Florida Keys
[
www.firescientist.com]