I full well understand sanding paint finishes, mechanical and chemical adhesion, and despite paint prep the POR peeled off. As someone responsible for the rust repair, the prep, and the painted products in my shop, I have to remove any such liability as this adhesion failure from my processes that would lead to rework.
I will use POR in inaccessible areas not affected by topcoat, such as inside of doors or other cavities. But for any area that is accessible for proper prep, ie: sandblasting or other abrading process, I use epoxy primer followed by the topcoat (given all the proper sanding steps in between). To date, using this process in my shop has been without any failure/peeling issues. Other than wetsanding, no special adhesion promoters or other crutches are required to insure one paint product plays nice with the others.
When POR was first formulated, I would suggest it was designed as a stand-alone product to combat rust issues. I've been there, done that. Bought POR years ago when all they sold was the black and silver, no other products. It wasn't until they realized it had UV deficiencies (fading on the black, silver turned a greenish shade) that they came out with other top-coating products, and it wasn't until they had adhesion issues that they started marketing their own adhesion promotor and metal etch. I don't need all these band-aids for epoxy primer to be compatible with the top coat of my choice, as a simple mechanical adhesion (wet sanding) will suffice. I stand by my statement that POR was/is a stand alone product as it does have adhesion issues with other manufacturer's products. Any calls to their tech line to discuss any failure of their product is quickly dismissed as an improper prep issue. As many of their customers are hobbyists who may be unfamiliar with how paint products should work together, they are more than accomodating to sell them more products to get the POR to function correctly for their circumstances.. If they are using it in conjunction with a top coated finish, hopefully it works for them.
Last edited by MPandC; 12/14/2011 6:21 PM.
