whats the secret to painting plastic parts

[guest01]

He all be painting some metric bikes. A lot of them use plastic fenders. I have been sanding with 180 then use 3 coats of catalized primer. Sand with 400. Seal with catalized sealer. Then I spray 3 light coats of hok paint. I keep getting some etching going on. paint cracking from solvent in paint I guess. How do I stop this??? Isn't sealer supposed to stop this?

 

[ezrider]

there are diffrent plastic primers for diffrent types of plastics, make sure your using the right one, try using an epoxy primer, you may have to use a water born primer. you did not mention if you were using a plastic primer( adhesion promoter). 180 may be too coarse try usijng a finer grit say 320 or 400 then using the plastic primer than epoxy primer /ubbthreads/images/graemlins/bigokay.gif

 

[guest01]

I am using the adheasion plastic primer first. my jobber said if i use this first I could use regular primer.

 

[rex]

You really don't need the regular or surfacer primer.Clean the plastic real good with soap and water and a plastic prep,plastic prime it and seal it.I'd probably lightly use a grey scuffy with the S&W for some light scratching but test a hidden spot to see if it's too course a scratch.If you want a better cusion thin your sealer a little more and use 2 coats if you can,but I wouldn't bother.Once it's flashed start painting.You want to keep the thickness down even more than a metal base.

 

[John Pierce]

Hey Reef, wassup? Yeah, what Rex said... I just use a coupla coats of HOK's sealer/primer directly on the plastic after I've sanded it with 220 - it doesn't really need the epoxy primer. Wash with soap and water *very* thoroughly before you start sanding - plastic is notorious for getting imbedded dirt and oil in the pores and sanding just pushes it in deeper.

JP