A number of products similar to WD-40 will work. Make sure they
contain a silicone lubricant. Most of what you spray will be the
petroleum solvent carrier, just as is the bulk of WD-40. This
is, of course, flammable. But it evaporates quickly, and with a
silicone lube, the remaining silicone film is NOT flammable.
WD-40 itself is probably safe too, since after a few moments,
the remaining film has lost most of it’s really volatile
componants (use the stuff with ventilation, for this reason).
And remember, steel is not flammable, and starts out at room
temp. It keeps a thin film, even a modestly flammable one, cool
enough so it won’t burn. I’m assuming, here, a film of a more
oil like material than a film of kerosene, so we’re talking about
the remaining oil, not the initial highly fluid sprayed on stuff.
And for really cheap and effective, forget the sprays. Get a
quart of any decent light motor oil. Most good motor oils have
corrosion inhibitors in them, and they really don’t burn easily.
Hit em with a torch, it might smoke a bit, or even burn while the
torch is on it, but remove the torch, it goes out. Safe enough.
You can use such oils to lubricate ingot molds, for example,
without setting fire to the shop. Or quench red hot tool steels
in them to harden. Similarly, no great flare up results…
Traditional “machine” oils are similar, but usually without the
corrosion inhibiting or cleaning additives. Just wipe the tools
down with a bit of the oil on a rag when you’re done using them.
Remember to store oily rags safely. Don’t pile them up all in a
bunch. hang them up on a towel bar or similar such solution, so
they cannot trap any heat that might build up from spontaneous
combustion. That is also much less a possibility with the
synthetic motor oils, as they are more combustion resistant in
general. Usually, when you go to use the tool, the slight film
of oil is not a problem. In those cases where it is in the way,
you can remove it easily enough with a little denatured alcohol.
Same thing if the tool has gotton cruddy with dirt or dust being
attracted to the oil. Just wipe it down again, or if it’s gummy,
clean it off with alcohol (or kerosene, or WD-40, which is mostly
kerosene anyway) and then re-oil it.