Need advice for refinishing black bumpers

[DMC3165]

A few years back the black finish on my tear bumper greyed out for now apparent reason. I sanded it down and re-sprayed it with dupli colors trim black. The result was better then I expected. But now its looking shabby again. So I did it again. It looks good but not great. There are a few spots that really don't cover evenly. I'd like a more professional look without the professional price. Anyone have any tips or advice? I'll post pics later.

[DMC3165]

Pics. Not bad from a distance. But not happy with it up close.

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[sdg3205]

A few years back the black finish on my tear bumper greyed out for now apparent reason. I sanded it down and re-sprayed it with dupli colors trim black. The result was better then I expected. But now its looking shabby again. So I did it again. It looks good but not great. There are a few spots that really don't cover evenly. I'd like a more professional look without the professional price. Anyone have any tips or advice? I'll post pics later.

Hey Chris,

When I towed 3205 out of the Arizona dessert, 75% of its fascias were toast. I had all the black on my bumpers professionally painted in satin black. In addition, they matched the near perfect original rear paint for the front. They also did the fake grill and the details around the DMC emblem and the spoiler.

It set me back about $540, but was well worth it. I love the look of the car with a more robust and permanent black. The light shines not only off the stainless now, but also the fascias!

With a little research I'm sure you can find something similar. All I'm saying is you wont regret it.

[DMCMW Dave]

Just keep cleaning and repainting.

But you could try something else.

The original finish is NOT paint, but the bare urethane. You can actually get fantastic results (with a lot of elbow grease) just sanding the original finish, using progressively finer wet-sand paper up to about #1800. And then just wax it or leave it.

[sdg3205]

Pics. Not bad from a distance. But not happy with it up close.

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It's starting to peel because of lack of prep work. The painter who did mine said he had never had such a hard time prepping a surface for painting. The first few attempts "fish eyed." 30 years worth of silicone and petrolium-based shiners, cleaners and "blackeners" basically get absorbed into the fascias and can be very hard to get out.

[DMC3165]

Was the bare urethane clear coated? I may try this approach next. How do you recommend removing the paint? Especially around the letters.

[Bitsyncmaster]

Was the bare urethane clear coated? I may try this approach next. How do you recommend removing the paint? Especially around the letters.

I found MEK with a Q-tip will clean out the letters and I saw no degrading of the plastic with the MEK. Not saying to soak it in MEK.

[outatym2001]

Was the bare urethane clear coated?

No.

It would be the most expensive solution to your problem but I recommend going the professional body shop repair route like sdg3205 says above.
Many years ago I personally did one hell of a good job painting my front and rear fascias with SEM Trim Black 39143. Near the same time I also used SEM Trim Black for the three metal trim pieces for the windshield.
Oh boy am I disappointed! Tiny rocks have chipped away at the paint and so I took the windshield trim pieces off and had them professionally powder coated with an exterior use powder coat.
I still have tiny chips in my front fascia where the black is. Some day I’ll pay the money and get them professionally done.

Wet Sand Bumper?
http://dmctalk.org/showthread.php?2391-Wet-Sand-Bumper

[DMC3165]

So I stripped my bumper today. Was a hell of a workout but was able to strip it down to the bare urethane. I'm definitely going to re-spray it. It's just too much for me to get the letters perfect.

I picked up SEM Trim black, but I also picked up SEM flexible bumper primer for urethane. Anyone tried it? I think it should give me a nice matte primer surface to work with. Will post more pics tomorrow.

[sdg3205]

So I stripped my bumper today. Was a hell of a workout but was able to strip it down to the bare urethane. I'm definitely going to re-spray it. It's just too much for me to get the letters perfect.

I picked up SEM Trim black, but I also picked up SEM flexible bumper primer for urethane. Anyone tried it? I think it should give me a nice matte primer surface to work with. Will post more pics tomorrow.

Looking forward to hearing the results

[Michael]

I would recommend Dave's approach to the bumpers, but if you are going to paint them, prep, prep, and more prep. Paint work is 90% preperation, and 10% painting. The 90% thats covered up must be done right.

Although I have never refinished a Delorean bumper, I have done hundreds upon hundreds of plastic bumpers, I am assuming there is no damage to correct first, so here is my advice:

After paint removal, wetsand the bare urethane with no harsher than 600 grit. Then move to 800. The reason being is you don't want to scar the urethane and have it start to "fuzz-up" on you, so basically you are sanding just as much as needed to give the surface some tooth for the primer to bite into. Now it's cleaning time again(no matter how clean you think it is, do it again with a good surface prep agent(I use an alcholol based prep that I wipe on and off). There are a lot of oils trapped in plastic/urethane bumpers, and these things are like giant sponges of sorts. If it has ever been dressed in the past prior to paint, it's even worse...As much dressing as I keep on my black parts, there is no way anything would ever stick to them no matter how much cleaning I did.

So now you have wiped down the bumpers and they are bone dry, now what? There are several products on the market to treat the bare urethane to accept coatings. "Bulldog" brand adhesion promoter comes to mind. This is a clear treatment sprayed on the surface just prior to paint. In some brands, they recommend painting over it while it's still wet. If you are going to rattle can the black, SEM also makes an adhesion product of their own. But first you MUST prime. This is where the rattle can method falls short. On most parts SEM is a God send. It dries flawless and you really have to try to mess up the finish it produces. But the front bumper is going to be subjected to a lot, and you have the adhesion problem to deal with so a 2 part primer(with hardener) is recommended here. If you must use a spray can type, be sure its an epoxy primer. Don't go overboard here, just a few light coats to cover the surface...and be sure to get black primer, not red or gray.

After priming, a light scuff pad prep and more cleaning agent/adhesion promoter. If I were doing this I would use a base/clear application designed for urethane, with some flex agent and dulling agent added into the clear for a semi gloss finish. If done right, it would look as good as(if not better) than factory dressed bare urethane bumpers.

If you are going to the spray can method, use the afore-mentioned SEM plastic adhesion promoter, followed by the SEM bumper paint. I believe SEM has a line of bumper coatings for this rather than using the old standby "Trim Black"..but ask the counter rep abvout which would work better.
SEM likes to be sprayed in warm weather, it's very hard to get this stuff to lay down in a cold climate. So make sure the temp(both ambient and surface) is at leat 70 degrees. Shake your can hard for at least a minute...it's hard to get mixed. You want your coats to be ligt and even, this stuff is also pretty transparent and hard to cover with. Resist the urge to spray heavy coats down(which is why I said earlier to use black primer). The plus is SEM dries quick, so by the time you have your first coat down on both bumpers, the previous will be ready for the second coat. Preferably you should be painting out of direct sunlight so the paint will flash for a few minutes, rather than dry as soon as you spray it. The final coat should be heavy enough to be wet for a few seconds...if you see a reflection you're getting it too heavy. Don't try to make a flawless, orange peel free reflection. In fact don't worry about the finish at all, if you keep your coat light and even it will dry flawless.

[1batt4u]

Why don't you bring it to PJ Grady?

[DMC3165]

When the bodywork gets to a point where I can't handle it then Grady's my go to guy. In this case I only wanted to the bumper right now and not the whole fascia. My biggest fear with that is after the rear is done I'd want to do the front to match and turn a small project into a big one and driving up the cost unnecessarily right now.

Anyway here are the results. It took me all week after work but its done and I'm more then happy with the results. I stripped the bumper to bare urethane attempted wet sanding it to buff it out but the letters were too much for me. So I continued to prep for paint. Primed it and sprayed it. I also used a heat gun to aid in the drying process which helped a lot.

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[dvonk]

good job chris, it looks great! :thumbup: