2K on Bumper Covers

E

El Toro

Member
When repairing bumper covers such as small spots to striping paint off to bare plastic what SPI primers are recommended and what steps should be taken,do you use flex additive? I use turbo after good cleaning but most is collision work on newer cars so don't see long term Thanks
 
!st always clean with an alcohol based wax and grease remover, never a solvent. (Honda first advised this about 15 years ago) Depending on the mold release, some can be smeared with a solvent cleaner.
Sanding should always be done with a grey scuff pad and sanding paste.
TPO, TEO, PP and PE all need a coat of adhesion promoter.
At that point for long term and chip resistance coat with epoxy next but in you case the turbo will save time.
Does not need a flex added but with any primer on a bumper you want it thin as possible.
 
Thanks but does this apply to old covers or used covers. New OEM cover with no primer I do as you say and no problems. I have a 04 Boxster to re do the front cover so will be sanding down to bare plastic.
 
I don't know what a boxer bumper is made out of.
If off the car should have a code on back.
If real flexible it does not need adpro, just clean and go with epoxy.
A simple test is, with a single edge razor blade, shave a small piece off an edge and put in water, if it floats you need adpro, if sinks, epoxy and go.
 
We had a 00' Boxter wreck that I fixed years ago. Repaired the torn plastic, sprayed epoxy over the ereas, filler, more epoxy and refinished. Paint never flaked and always looked good.

Now I would use plastic adhesion promoter if needed but I never did back then. Wasn't using waterborne back then either. Just the old prepsol.
 
Flex additives were really old technology for acrylic lacquers and enamels. Pretty sure the bumper covers are some form of polyurethane anyway. The house of color adhesion promoter I used seemed more like like super 77 spray adhesive.
 
Standox's most modern 2K products still require the addition of a flex additive (15% before activation) so I'm not sure what to think about the whole flexibility thing sometimes. I know there are a lot of primers out there that shouldn't be used on flexible parts.
 
crashtech said:
Standox's most modern 2K products still require the addition of a flex additive (15% before activation) so I'm not sure what to think about the whole flexibility thing sometimes. I know there are a lot of primers out there that shouldn't be used on flexible parts.
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I remember reading years back in the old SPI forum Barry mentioning the chemical name of what the flex additive actually is. And he also pointed that it stays on the paint for only a few months. I kinda figured it was one of those products that companies like to sell just for the sake of making some extra coin. I have no idea if it's snake oil or if it has any real value to the quality of the paint job.

I hate being so cynical at times........
 
Does any one use a " flexable primer " like SEM or other co sells? Other wise I use SPI Turbo all the time every day.
 
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