Need help with prepping and painting plastic bumper

Gary Longfellow

Promoted Users
I need advice on repairing,priming and painting a plasic bumper on a newer mustang.I have been painting using spi products for over ten years but have not needed to paint a plastic bumper.I purchased one from the salvage yard and it has scrapes and the paint is peeling in places.What products are best for filling scratches in the plastic? Also I use spi epoxy all the time but not sure how to use it on plastic.Please advise.
also I would like to paint it base clear coat using universal clear .Do i need a flex aditive to base and clear??? also what plastic filler to use for scratches? Adhesion promotors needed?
thank you
Gary
 
First determine if the paint on the bumper is OEM or refinish. If its refinish it needs to come off for best longevity. If it's OEM that's great. leave it on because it will be an excellent base for what you are going to do. Sounds like bumper has been repainted if it is peeling as that is a red flag. Because of that (peeling) I would also try to determine if it is an OEM bumper or an aftermarket one. If it is aftermarket I would see about returning it. Only reason to buy a bumper from a salvage yard is to get an OEM one. Doing all the work that is required to fix it is kinda pointless on a aftermarket one. Borderline on a OEM one when you consider what you can a quality aftermarket one for.

Irregardless if it is peeling that means it is refinish and it needs to come off. There are plastic specific paint strippers available SEM is a good choice. Either of these two work OK.

Or you can sand/blow it off. Most of the time even when using stripper you will have to sand the cover to get it all off. It can be painstaking and time consuming. If it is OEM paint underneath you want to leave that. Urethane stripper is designed to only remove the refinish paint. Not the OEM as that is the best base to start with.

So after you get the paint off, you can sand light scratches/gouges out of the cover without any filler. Deeper gouges, most body shops just use conventional glaze. In thin coats it works pretty good. Yes it will crack if flexed to much but if you hit something that flexes it that much there is going to be other damage anyway.
I've generally only repaired bumper covers the Collision Repair way which is to fill defects on the plastic directly then prime. If you have the time a better way would be to sand and expose the gouges trying to feather them out slightly and remove any fuzzy plastic, then adhesion promoter on all the bare plastic and then epoxy. After epoxy has set up for the required time 24 hours (min) -48 hours (better) then apply your choice of either conventional glaze or a bumper specific product like UPOL Stronghold. Get everything corrected then re-prime with epoxy after applying adhesion promoter again over any bare plastic areas exposed during the sanding process. Sand the primer until it's ready for paint just like you would a metal panel. Never use anything coarser than 180 grit during the entire process.

No need for any flex additive in your clear. If you use epoxy for your primer it will help with minimizing any cracking. But again generally you only get cracking if you bump or hit something.

Ask more questions if you have them. :)
 
First determine if the paint on the bumper is OEM or refinish. If its refinish it needs to come off for best longevity. If it's OEM that's great. leave it on because it will be an excellent base for what you are going to do. Sounds like bumper has been repainted if it is peeling as that is a red flag. Because of that (peeling) I would also try to determine if it is an OEM bumper or an aftermarket one. If it is aftermarket I would see about returning it. Only reason to buy a bumper from a salvage yard is to get an OEM one. Doing all the work that is required to fix it is kinda pointless on a aftermarket one. Borderline on a OEM one when you consider what you can a quality aftermarket one for.

Irregardless if it is peeling that means it is refinish and it needs to come off. There are plastic specific paint strippers available SEM is a good choice. Either of these two work OK.

Or you can sand/blow it off. Most of the time even when using stripper you will have to sand the cover to get it all off. It can be painstaking and time consuming. If it is OEM paint underneath you want to leave that. Urethane stripper is designed to only remove the refinish paint. Not the OEM as that is the best base to start with.

So after you get the paint off, you can sand light scratches/gouges out of the cover without any filler. Deeper gouges, most body shops just use conventional glaze. In thin coats it works pretty good. Yes it will crack if flexed to much but if you hit something that flexes it that much there is going to be other damage anyway.
I've generally only repaired bumper covers the Collision Repair way which is to fill defects on the plastic directly then prime. If you have the time a better way would be to sand and expose the gouges trying to feather them out slightly and remove any fuzzy plastic, then adhesion promoter on all the bare plastic and then epoxy. After epoxy has set up for the required time 24 hours (min) -48 hours (better) then apply your choice of either conventional glaze or a bumper specific product like UPOL Stronghold. Get everything corrected then re-prime with epoxy after applying adhesion promoter again over any bare plastic areas exposed during the sanding process. Sand the primer until it's ready for paint just like you would a metal panel. Never use anything coarser than 180 grit during the entire process.

No need for any flex additive in your clear. If you use epoxy for your primer it will help with minimizing any cracking. But again generally you only get cracking if you bump or hit something.

Ask more questions if you have them. :)
thank you very much for the info
Gary Longfellow
 
Chris has given great information and I would like to add before sanding clean clean and clean. Sem and other co's make a plastic cleaning paste that is used before sanding.
 
I have used the search bar with no success with how to's for a 2003 ford ranger front bumper valance, The back of the valance has some numbers with AB stamped on it. I cut a piece of the material off and it floats in water so I assume to adpro, epoxy and paint?
 
Did you price out a replacement part first? I would think if the paint is peeling, it is most likely not factory paint and the time to get that off would be better off with a replacement. The replacements come brown they say not to remove because it is the primer the factories use on plastic.
 
I have used the search bar with no success with how to's for a 2003 ford ranger front bumper valance, The back of the valance has some numbers with AB stamped on it. I cut a piece of the material off and it floats in water so I assume to adpro, epoxy and paint?

If it floats then yes you would use promoter.:) Prep it with a grey scotchbrite pad and scuff stiff or the equivalent. Then apply the Ad-Pro per the instructions.
 
So use a gray scotch bright or up 180 grit sand paper? what adhesion promoter do you recommend?
 
So use a gray scotch bright or up 180 grit sand paper? what adhesion promoter do you recommend?
180 grit should be the coarsest that you use in the entire process. Example....when sanding old paint off the cover or sanding any type of filler. Anything coarser than 180 on a bumper cover is to aggressive for the plastic substrate. (cover)

Grey scotchbrite (3M 7448 or equiv) is used in conjunction (usually) with a sanding paste (Presta Scuff Stuff or equivalent) as your final prep before applying adhesion promoter.

SPI Adhesion Promoter is an excellent product. It is my preference nowadays. There are many others, check with your local Paint Jobber.
 
Back
Top