(QUOTE) I could cause pin holes by cranking up the air pressure. I believe this forces air into the paint that then rises to the surface and pops.

Interesting theory, but in 40 years I've never seen or heard of this happening. Usually it is a surface contaminent, something coming through the air line, or pin hole. If you've ever painted over bodywork with pinholes in it, you'd know how it looks. As I said, I just had it happen on powdercoat myself, and it was very slightly pinholed. I don't know how it is produced in the powdercoting process, but it was there.