What is everybody's favorite chemical for removing cured epoxy?
I've picked up a complete, but poor condition Greene bolt action in a trade. For reasons unknown, a previous owner painted all the metal with a silver flake epoxy, including all the seams around the bolt and lugs. The coating looks very much like Pettit Trailercoat, which is an aluminized urethane epoxy. I have managed to strip all the surface coating, and free every single moving part, except for the bolt, which has no handle and remains stuck shut. I have located a spare bolt handle, but I must remove the current bolt. After a few days of experimentation, here is what I have tried and my thoughts on each approach.
Clean Strip Premium Stripper - Half hour soak softens the surface enough for a bronze brush to scrub surfaces clean.
Acetone - Half hour soak softens enough for a bronze brush to scrub surfaces clean. It evaporates too quickly for brush application, but immersion worked well for the small parts.
Xylene - About as effective as acetone, but more useful - the slower evaporation rate allows for useful brush work, and wrapping the work in tinfoil greatly enhances the soak time.
Methyl Ethyl Ketone - Seems about as effective and useful as Xylene. Evaporation rate somewhere between Xylene and Acetone.
Heat - Epoxy should soften around 400°F, but that is well into the tempering range of modern steels. I have no idea if it would harm 1860s alloys, nor do I know if such alloys would respond to modern re-heat treat methods. Photos of other rifles show the bolts as either bright or blued, not case-hardened.
NONE of the chemicals have succeeded in softening more than a thin layer of epoxy, even after 24 hours. This isn't a problem when you are scrubbing accessible surfaces, but now I must penetrate into the inaccessible bolt lugs and races. I have soaked the action overnight in each of the above solvents, and the bolt remains firmly stuck. This evening will be day 2 of the MEK soak, but I don't expect it to be any better than day one.
*Edit - I am aware that there is a button that must be pressed to unlock the bolt. That locking system has been removed for cleaning, and is not the source of the bolt remaining stuck.
So, if you need to remove thin coats of cured epoxy, any of the above chemicals will do nicely. If you have ever succeeded in softening thicker layers, I would love to hear your thoughts and experiences!