Hi Guys
I even used Por's Metal Etch or Metal Prep and still had problems with pealing. Jordan you are probably on track with your comment that the prepared steel feels like 100 grit sand paper.
Here is an example of the problem I was having this is a lower fender where new steel has been welded in to replace rusted area.
I really should have ground the steel area with 80 grit disk to give the Por 15 something to mechanically grab on to. Guess the rule with Por 15 is if the metal feels smooth it will not stick.
The other side of the getting paint to stick is as Bob mentions you have to use Por's Tie Coat Primer if you want the top coat to stick.
Cheers Phil