Front bumper spraying?

hi everyone,i have just bought a red front bumper from this site and i need to spray it black. due to experience of getting my current front bumper resprayed, 3 times, i am trying to find out if the bumpers are made from a reactive plastic ? my friend has sprayed lots of cars for me but has failed 3 times with my supra front bumper. on the third attempt he ground back to the base plastic and filled with epoxy, this was thought to be the answer to the two previouse attemps failing. the failure is blisters in the paint after 4 or 5 weeks. we even tried leaving the grey primer for 3 weeks to see what happened, it was ok, but after applying the black paint and laquer, 4 to 5 weeks the blisters start appearing all over the place. ? herbiemercman.

I am not a sprayer but if i recall primer is not water proof and could hold a small amount of water, also has you mate got a good water/filter trap, this could cause micro blisters with the water in the air line, had this happened to me, also is it black base coat that you are using if yes dont leave it too long before putting on clear less than an hour with some of the paints that i have used. are the blisters in the clear or base. are you using panel wipe before painting as grease from your hands could cause problems. hope some of this helps if not someone on here will know the answer. regards chris

If they are micro blisters, then its down to moisture in the paint, can be caused by quite a few things like, bad water traps, contaminated paint sprayed in damp conditions, paint/primer left too long between coats etc etc!

If they are fish eyes, spot where the paint has not adhered, its down to grease on the surface

Where was it sprayed? in a proper booth, was it baked afterwards?

I presume your mate used 2K paint?

When you sanded the bumper down to bear plastic did you plastic prim the bumper before putting on the primer , if you did'nt thats your problem the paint is not slicking to the plastic . Rich.

many thanks, chris, tricky and richard, all your comments make much sense. i will take the replacement bumper to somone who has more suffisticated equipment all be it i would like to see if my friend suffers the same problems with the replacement bumper as it is sprayed red from toyota and is in very good condition. herbiemercman.

You also need to use a good quality thinners.

At first you tried plastic primer?

The bloke that painted Mark Evans E- Type on the tv I recall mentioning that some primers, I think he said acrylic in this instance shouldn't be wet sanded prior to putting on a top coat as they'll absorb and hold onto moisture. I don't know if it's possibe to dry them out first if you do wet sand.

hi merckx, thankyou for your comments, i think you are right as my friend tried evrything, but i know he or i was not aware of this idiosyncracy with acrylic grey primer being pourous and absorbant. removing all traces of grease and moisture are very important. the only thing that confuses me is WHY has this situation only shown itself on a plastic bumper? herbiemercman.