Promoter needed for polycarbonate?


New Member
I’m doing some custom headlights, i de-chromed the internal plastics and I need to paint them. They’re marked “pc” which according to Google is polycarbonate. It doesn’t float it sinks, if that matters. So questions..

1: does it require adhesion promoter?

2: if it doesn’t, is there harm is using it anyway?

3: is it better to use catalyst in the spi promoter?

4: can I spray base coat over the promoter or would a primer be better suited?
If it floats promote.

If it sinks I don’t. When I painted golf carts I did not use promoter, just epoxy because they’re not floaters.

I always do epoxy first on any substrate though it may not always be necessary. I’d almost have to guess it will stick better than straight basecoat would.
1. No
2. Bond will be better if you don't use it. It has been my understanding that in situations where it isn't needed using it doesn't allow for as good adhesion. No need for it with PC.
3. Yes. Use it when you need to use ad-pro. Completely changes the product for the better.
4. I would epoxy first then apply base. SPI Epoxy reduced 10% would work well and you would not need to sand. Final prep before sealer I would sand everything with 400. Either by hand or machine.
In a situation where you did use adpro, you can directly base over it, but it's usually better to seal so that you are closer on the greyscale to your color in order to minimize the amount of base used.
Great, thanks for the replies. The parts are all pretty round and contoured, so I am thinking red scuff pad and scuffing paste?