I used acetone because the resin was kinda slippery so I wanted to remove all the mold release. I don't know which primer I used but that has to be it. I've got some great automotive primer now, but dag nab it its gonna be a bitch getting the paint off. I can put it in the tub and scrub away, but its foam filled and if I get too much water in there, I don't know how it ever dry out.