quote:Originally posted by Johnny Woods:
I have achieved the best results by using the following methods:
After blasting I apply self etching primer. As soon as I have finished shooting the primer I apply two pack (urethane) in body colour or black, solvent based not water based. It's very important to overcoat the primer within a few hours, the sooner the better for maximum adhesion. If I am spraying a small part I overcoat the etching primer as soon as it has flashed off. If you leave it until the next day it would be necessary to Scotchbrite the primer and even then it would not be nearly as well stuck as if you had done it immediately after shooting the primer and would chip off much easier.
I then overcoat that with Wurth body schutz (or equivalent product from 3M).
I would not use Por 15 at all. From what I understand it was developed to paint over rust and does that very well but does not adhere to clean metal nearly as well as self etching primer.
Always call the tech line number on the side of the tin to make sure you get the drying windows right, this is the key to maximum adhesion. Dont use anything that comes out of a rattle can unless it's small unimportant parts that are not worth cleaning you gun out for.
Wear an air fed respirator for anything containing isocyanate.
Johnny
Actually it adhered fantastic to sand blasted metal which is in there spec sheet. hey push for their product "Metal Ready" which etches it and increases the mechanical adhesion but that sand blasting is really optimum.
I etched primed parts of mine but epoxy does adhere better. Modern epoxies are head and shoulders above what they used to be and provide a moisture barrier.