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-   -   Process when painting car with urethane bumpers (http://www.hotrodders.com/forum/process-when-painting-car-urethane-bumpers-222069.html)

TNshadetree 07-24-2012 07:10 AM

Process when painting car with urethane bumpers
 
I'm painting a 85 Monte Carlo SS with urethane bumper covers and I am considering what steps to go through.

I have planned on only using epoxy and then SS urethane paint on the bumpers which are prepped with 400 grit. While the body is prepped with 180 and will get epoxy, 2K surfacer and then SS. Just curious what process you guys usually use.

Since I don't want to use a surfacer on the bumpers I've considered addressing them separately. I've considered a couple of ways.
1. Shooting everything with epoxy, mask the bumpers while I shoot the body with surfacer. Then after blocking out the body, sanding the epoxy on the bumpers with 400 so they are ready for the SS.
or
2. Shoot the body with the primers and block it out while keeping the bumpers masked and raw. Then addressing the bumpers first by shooting epoxy followed by SS to cross-link. Then I would mask the bumpers up while I shoot the body with the SS.

What is your usual process?

cyclopsblown34 07-24-2012 07:50 AM

Thanks for posting this question. I'm about to start on a 1990 T/A and the front bumper has a little damage on it. I was considering sanding or stripping it to urethane and then epoxy primer, flexible filler, epoxy primer and then paint.

AutoGear 07-24-2012 08:14 AM

When I did my 87 TA; I scuffed the bumper covers and side skirts, minor body work (flexible filler, used a 2 part epoxy suitable for urethane to repair a crack). This is where it gets murky; I know I used Bulldog adhesion promoter, but I can't remember if I applied it to the substrate and then put my epoxy sealer over it, or vice versa. The next day I applied Bulldog (2 very light coats, heavy coats can cause problems) and shot my base clear over the top.
Im not sure if you need the sealer or not; but the base I used didn't cover great, and I wanted an even substrate. 4 years later and the bumpers look great; the rest of the body is starting to show its age now (parked outdoors, sees rain, drive down a dirt road quite often)

cyclopsblown34 07-24-2012 08:16 AM

Thanks Nate. :thumbup:

AutoGear 07-24-2012 08:30 AM

Chip;

No probs. I repaired a lower valance for a tooner kid; and he was pretty short on bucks (apparently cutting coils to save money, means every time you drive over a bump, you have the extra money to repair the flattened muffler, wrecked rims and ground f/x). This time I wetsanded it, spotted in over some nicks and dings, used DUPLICOLOR adhesion promoter and some left over black semigloss from a snowmobile project. It didn't fail.

cyclopsblown34 07-24-2012 08:34 AM

Quote:

Originally Posted by AutoGear (Post 1576656)
Chip;

No probs. I repaired a lower valance for a tooner kid; and he was pretty short on bucks (apparently cutting coils to save money, means every time you drive over a bump, you have the extra money to repair the flattened muffler, wrecked rims and ground f/x). This time I wetsanded it, spotted in over some nicks and dings, used DUPLICOLOR adhesion promoter and some left over black semigloss from a snowmobile project. It didn't fail.

You're fiddling with all kinds of car stuff. That's way cool.

MARTINSR 07-24-2012 09:48 AM

I know you don't want to hear this but there is no way I would be painting that car without removing the bumpers. The time spend removing them is FAR less than trying to do a different procedure than the body and masking them off over and over and all that, it is MUCH faster to remove the bumper and work with them off the car.

Brian

cyclopsblown34 07-24-2012 09:54 AM

Now that Brian has posted in here. What is your preferred procedure for repairing damage to these urethane bumpers? I had one years ago I fixed and the discolored area of the urethane shone through the paint like a beacon saying lookit what Chip screwed up. It's been so long ago, I cannot remember the procedure or materials I used.

AutoGear 07-24-2012 09:55 AM

TOTALLY missed the part where he said leave the bumper on. When I removed my bumper covers, I found all kinds of dirt/trash behind them. This would have been absolutely awesome to have blown out from behind the bumper when you're on your last color coat pass with your spray gun. They take literally minutes to remove. Side note; my TA used different length fasteners for different parts of the plastic, so put em back where you got em

cyclopsblown34 07-24-2012 10:02 AM

Exactly Nate. removing the panels is way easier and cheaper than fixing dirt that ends up in the topcoat.

MARTINSR 07-24-2012 03:09 PM

Quote:

Originally Posted by cyclopsblown34 (Post 1576675)
Now that Brian has posted in here. What is your preferred procedure for repairing damage to these urethane bumpers? I had one years ago I fixed and the discolored area of the urethane shone through the paint like a beacon saying lookit what Chip screwed up. It's been so long ago, I cannot remember the procedure or materials I used.

I have to say I have zero bumper repair experience if it involves a tear. We send out all bumpers with any kind of structual damage and have at everywhere I have ever worked.

We have them "remanufactured" and they do a pretty darn good job. Check in your area and see what they would charge. If they ask you how much they sell for new always give the the lowest price you can come up with because they usually set their reman price in relation to the new replacement cost.

Brian

tech69 07-24-2012 07:46 PM

Quote:

Originally Posted by cyclopsblown34 (Post 1576675)
Now that Brian has posted in here. What is your preferred procedure for repairing damage to these urethane bumpers? I had one years ago I fixed and the discolored area of the urethane shone through the paint like a beacon saying lookit what Chip screwed up. It's been so long ago, I cannot remember the procedure or materials I used.


some guys swear by plastic welding and some swear by plastic repair netting on the backside. Some people actually think heating up a screwdriver and remelting the plastic onto each other is welding...sort of, but the oils in the bumper will make it hard to adhere to each other and it will fail. Anyhow, the correct way is to locate the type of material it is inside the bumper cover. It will be a few letters like a paint code. Then you get the correct plastic rod and do a test on the backside to make sure it sticks well. Then you weld it. Most use hot air.

The correct way to net repair is to groove out the backside and frontside with a die grinder. Then throw tape in the hole you made bigger by grooving it out. Then add your plastic repair, then net, then more plastic repair. When it cures take the tape off and do the outside. Most people don't wait for it to cure and do both sides together.

Use flexible filler to top coat.

If you're working road rash than stick 80 grit on a da on it carefully. Then go over it with 180 for a long time to take the little fur balls out that collect when using 80 grit. Using 180-220 with the paper wet will get the fur balls out really fast. If you don't account for the fur balls you will be disappointed when you prime and see your wet primer so I'd never suggest 80 grit to someone who hasn't done many bumpers. Then use plastic repair if needed or a flexible filler . Some people use brown flexy crap that sands like junk instead of a flexible filler but I think it's junk and doesn't adhere well. Once you got the fur balls out you prep like anything else you'd spray but you spray a little adhesion promoter on bare plastic beforehand and add adhesion promoter to your primer, depending on what 2k you use. No need for adhesion promoter in your paint or clears anymore, or at least that's what is now guideline.

MARTINSR 07-24-2012 11:14 PM

Henry, the other day a guy came in and did a demo with a plastic welder that was REALLY good. That sucker worked like magic, but it was damn expensive. I forget how much but it was thousands as I remember.


Brian

TNshadetree 07-25-2012 08:12 AM

Since I don't have repairs to do, do you guys think I'm OK with my 400 prep for the epoxy then paint? Or should I go a step courser like a 220 or 180? There is only one place where I'm down to the plastic itself so is there any need for a adhesion promoter before the epoxy?

With 400 my worry is whether the epoxy has enough tooth, with 180 or 220 I'd worry about sand scratches showing through. Perhaps I worry too much. Right now the plan is 400, epoxy, paint.

cyclopsblown34 07-25-2012 09:10 AM

Thanks Henry and Brian. I'm not dealing with much more than maybe some gouges on this car and none I saw went all the way through the bumper. I definitely want to do it right and figured you guys could set me straight.

TNSHADETREE, sorry for the threadjack.


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