Parts Washer, What Solvent?

Don't use Kerosene! I carry a sealed pint bottle (made specifically for flammable fuels) of Kerosene to start wet wood on fire when I'm camping. IMO, it's as flammable as straight gas but doesn't smell as bad (doesn't seem to taint food). You mentioned you don't smoke (I do), but all it would take is one errant spark from a grinder or busted light bulb (ever swing a ladder around your shop?) to send your projects up in smoke! I can't imagine what 15 gallons of kerosene could do.

I use Castrol non-flammble solvent. It doesn't work as well as Safety-Clean, or any other flammable sovent but it works well enough, is biodegradeable and I can sleep at night.

Second choice would be Safety-Clean. It's very hard to ignite (you can take a propane torch to it, and until it starts to turn to vapor, it won't start on fire), but it is an excellent solvent.