On a bodyshop forum some time ago a guy did a test with epoxies. He sprayed them out then tested with lacquer thinner, to see if they would come off. He tried several types of epoxy, testing at a couple days, a week, etc. I did a test with Kirker at the time and I do not remember the exact time I waited , a day two days????? . . . but nothing came off with the lacquer thinner. I can throw some leftover in my shop refrigerator and get a few more days out of it. But given normal temps it's sandable in a couple days in the sun or the next day if given some heat. I admit, I do mix and match materials, but have found a "system" that works and stay with it as much as someone may stay with one line . . and for the same reason, it works.