Primer over metal?

I use either Gunze or Tamiya primer.

Alternatively you can also sand the parts with 400 grid paper or soak them for a bit in vinegar. I do both at times depending on the part and where it is going to be used.

I was doing some PE harnesses a couple of months ago and wanted the same answer to that question. I took a couple of pieces of PF fret and tried different thigns. On one piece I primed one side and the other I left bare. The other piece I etched in vinegar. I painted all of them with the same acrylic paint at the same time, and once it was cured I twisted them into tight little bends to see which popped off the easiest. Surprisingly none of them did. All three scrape off easily, but they didn't just pop off. Since then I've just been cleaning the PE parts with alcohol and painting them with acrylic.

Thanks for the advice I think I will try just cleaning the parts and then painting them, maybe some clear coats will stop the paint scratching off!

QUOTE: Thanks for the advice I think I will try just cleaning the parts and then painting them, maybe some clear coats will stop the paint scratching off!

That's what I usually do, and it works for me. Doesn't mean it will work for you though Some primer that adheres to metal should, in theory, make the final color coat much tougher. Problem is that I haven't found any primers that adhere to PE that well. For white metal parts I use Tamiya primer. It works well, but I haven't use that many white metal parts. Anyway, good luck with it. Hope it works OK for you.