How would one go about to fix this issue on my bumper? Would the cracks come back if I were to spray 2 coats of epoxy over it? Bumper is off a 1982 camaro. The cracks are not through to the other side if that helps. Thanks for any replies on this issue.
Bumper repair or epoxy it
- Thread starter Pete
- Start date
metalman
Oldtimer
The cracks are the 38 year old dead paint and who knows maybe repaint as well. I agree it has to be removed if you want it to last.
Stripping the old paint off of those old covers isn't easy with sanding. Not sure what is available in your area but here we have an outfit that might be able to media blast off the paint. They know what to use and how to do it without wrecking the plastic. Still need to surface it and epoxy would be the way to go with that.
Stripping the old paint off of those old covers isn't easy with sanding. Not sure what is available in your area but here we have an outfit that might be able to media blast off the paint. They know what to use and how to do it without wrecking the plastic. Still need to surface it and epoxy would be the way to go with that.
Chris_Hamilton
Trying to be the best me, I can be
Soda blasting would be the best choice....bumper safe paint stripper then sanding would be the only other real option. Straight sanding would be my last choice if I was doing the job.
www.semproducts.com
If in doubt about what type of plastic, do this. Cut-off a small sliver of the bumper on the backside. Get a glass of water. Put the sliver in the water. If it floats it needs adhesion promoter. If it sinks it doesn't. Like Crash said once....."If it's a floater you need promoter"
Paint Strippers | Refinish | SEM Products
www.semproducts.com
If in doubt about what type of plastic, do this. Cut-off a small sliver of the bumper on the backside. Get a glass of water. Put the sliver in the water. If it floats it needs adhesion promoter. If it sinks it doesn't. Like Crash said once....."If it's a floater you need promoter"
Thanks, so more sanding is required. Fun times ahead for me. I have removed all layers of paint/primer already which took forever and now down to the urethane. I have checked it and it sinks, so no promoter needed.
once the spidering is gone, just fill in with a bumper glaze. I imagine there will be an indentation.
once the spidering is gone, just fill in with a bumper glaze. I imagine there will be an indentation.
Chris_Hamilton
Trying to be the best me, I can be
Ok I see that the paint is stripped. Before I would sand it out (which will weaken that area considerably), being that it's urethane and the cracks are not through to the other side you could try this. Use a heat gun and heat that area until its hot enough that the plastics starts to goo. Then let it cool. That should be enough to cause those cracks to reform a bit. You could try paddling it with a putty knife while its hot like that.
One thing you don't want to do is thin that area down so much that it becomes an issue. Thin it down and fill it with glaze it will be weak and the glaze will crack really easily. Heating it will de-stress and allow you to keep the material.
One thing you don't want to do is thin that area down so much that it becomes an issue. Thin it down and fill it with glaze it will be weak and the glaze will crack really easily. Heating it will de-stress and allow you to keep the material.
I would put it in the sun for a day or 2, clean it with 700, and spray 2-3 full wet coats of unreduced epoxy. Put it back in the sun after overnight dry for a day or 2. Sand it with 180 or finer and see if the spider webbing is gone. My guess is it will be, and if it is, it will not come back. I've done this on lots of very thin fiberglass parts that are more flexible than that bumper, with excellent results. Can't beat epoxy as a flexible repair material, better than any urethane, IMO.
metalman
Oldtimer
I missed that the bumper was stripped!!!
Its like flex cracks from a possible impact similar to what fiberglass does. I was with the repair in the video until he used water based primer and 320 to block. I don't know anything about that primer so I would have used SPI epoxy.
The few times I repaired modern bumper covers ate enough time that I understand why production shops mostly replace the covers and reserve repairs for smaller minor damage. Seems there are better materials these days for repair and filler.
!!Its like flex cracks from a possible impact similar to what fiberglass does. I was with the repair in the video until he used water based primer and 320 to block. I don't know anything about that primer so I would have used SPI epoxy.
The few times I repaired modern bumper covers ate enough time that I understand why production shops mostly replace the covers and reserve repairs for smaller minor damage. Seems there are better materials these days for repair and filler.
metalman
Oldtimer
I once brought a pair of old Harley fiberglass saddle bags to the blast shop. He had me wait while he test blasted and turned out whatever paint someone put on them was so soft and gummy he couldn't do the job. Had to use paste stripper and hand strip.Soda blasting would be the best choice....bumper safe paint stripper then sanding would be the only other real option. Straight sanding would be my last choice if I was doing the job.
Paint Strippers | Refinish | SEM Products
It is a urethane bumper, and no adpro is needed.
Corvettes starting in 74 have this issue from deterioration but worse as with the gto endura bumpers.
First, afoot note to what im saying for repair, not all epoxies have good flex, so im only speaking for spi epoxy.
If cracks are not repaired, they will work its way through urethane primer and paint to show up again.
How we do the vettes and gto is 3 to 4 coats of spi epoxy unreduced, next day sand smooth with 1500 and base.
Spi is flexible at 4 inches thick and when cured stronger than a gell coat.
They are not coming back with this repair.
Corvettes starting in 74 have this issue from deterioration but worse as with the gto endura bumpers.
First, afoot note to what im saying for repair, not all epoxies have good flex, so im only speaking for spi epoxy.
If cracks are not repaired, they will work its way through urethane primer and paint to show up again.
How we do the vettes and gto is 3 to 4 coats of spi epoxy unreduced, next day sand smooth with 1500 and base.
Spi is flexible at 4 inches thick and when cured stronger than a gell coat.
They are not coming back with this repair.