I use 'Adhesion Promoter' by Dupli-Color. An 11 ounce can is under 6 dollars at automotive parts stores.

Sprays on clear like Tamiya metal primer, dries faster and I think is the best without going to an expensive etcher primer... especially on smoother surfaces. Of course, I still prep them with a light scoring of wet sand paper.

Much less expensive $$ and you get more than twice the amount. Will work on plastic as well.




Jeff