Yep, this stuff does not stick to bare metal,you must use epoxy or etch primer to avoid adhesion problems.As for not drying that one time, you must have overshot some MEKP . I know this because one time I needed to shoot a spot of this primer and wanted it to dry quick, so I squirted a lot more of the hardener than what they recommend,it wouldn't dry ,even with infared light.So after an hour under the light,I scraped it off,mixed a new batch from same container with proper amount of MEKP and what do you know? I was dry within an hour without infared light.