When we took stock making in school one of the students remarked that he put his stocks in the oven to heat them. The instructor asked him if his home owners insurance covered arson. Messing with solvents in the basement is fine so long as you get the job done before the fumes reach your furnace or water heater. NUFF SAID?
There is nothing inherently dangerous with putting your stock in an oven heated no higher that 175F. Cosmoline melts at 113–125 °F (45–52 °C) and has a flashpoint of 365 °F (185 °C).
It is not going to explode, and is not a risk so long as you have not saturated it with flammable solvents.
So far I've de-cosmolined about six stocks with no ill effects (I do open the windows though.)
Ideally, it would be done outside in a homemade solar oven over a period of days or weeks, but in Canada there is a brief season for utilizing that free heat.
I have heard of guys covering their stocks with kitty litter, and placing them in a black plastic bag out in the sun, or in their car on the dash.
I place the UNTREATED stock in the oven, and remove periodically to wipe off with a clean, blue shop towel (moistened and slightly damp with cool tap water.)
I apply mineral spirits at the very end (after I am satisfied I have removed as much cosmoline as possible) to remove the tacky residue. At that point, I have finished exposing the stock to heat.
I don't leave the room when I am working on a stock, and I place aluminum foil on the lowest rack to catch any dripping.
I have tried whiting mixed with acetone, and a heat gun. As well as kitty litter inside a foil pouch.
By far the easiest, and cleanest method, is just to stick it in the oven untreated and bare.
Once it starts flowing, it is like watching sap ooze out of a tree.