Front grille repair

I have been doing paint and body as a hobby for 35 years. You never let epoxy primer dry in a paint gun. If you do that, even MEK wont touch it. At that point you might as well remove your air fitting and toss the paint gun in the trash. As soon as I am done spraying anything especially epoxy primer, I clean it out right away.

I have used lacquer thinner in a pinch to clean out epoxy primer. It doesnt mix with epoxy primer, it makes it look a whole bunch of little tiny bread crumbs floating in the lacquer thinner. Do what you want, but this tells me the lacquer thinner is not mixing in with the epoxy primer. If any of that swill is left behind during cleaning it will dry, solidify, and ruin the gun.