Tips for painting raw metal bumpers

Rustynj

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Expecting my dirtworx bumpers any day. How many coats of primer, top coat? Any additional coating? Any tips welcome. Largest paint project to date.
 
One coat of Rustoleum self-etching primer followed by a coat or two of Rustoleum Satin Black works really well on unpainted bumpers like that and is how I painted my two Dirtworx bumpers.

Make sure to adhere precisely to the timing instructions for subsequent coats though. You can apply a second coat within 30 minutes or so but after that you have to wait something like a week IIRC for it to cure before more coats. If you don't the paint will craze!
 
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I followed this process for my rear bumper and sliders, both of which were shipped raw.

Wipe down dry, then scuff the surface lightly with a 3M pad or 600 grit sand paper. Wipe all debris while dry, then clean with mineral spirits and allow to dry.

2 coats Rustoleum self etching primer, followed by 2-3 coats Ace Hardware Satin Black Enamel (both rattle can varieties). Follow the timing instructions to the tee, as mentioned above.

I went with the Ace product because my local store didn't have the Rustoleum in satin black when i did the bumper and It turned out so well, I used the same for the sliders. Very happy with how both turned out.
 
When I painted my rear flares I used Acetone to clean, sanded with scotch brite red, acetone again, dry. 2 coats primer, wet sand after 15 min with higher grit scotch brite, dry sand after 4 hours with same level pad, and then apply the red, and then clear coat 30 min after. The paint held up really well for 3 years before I sold them. They had rock rash but the primer below stayed mostly intact and underneath the flare held up very well considering they were exposed to whatever the tires threw at them.

Freshly painted and dry
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After 3 years on a DD and a lot of trail time
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Ideally, I would sand blast everything, spray with two coats of epoxy primer and two or three coats of single stage urethane. Maybe you could find somewhere that does wheels to sandblast and powdercoat or sandblast and paint with catalyst paint.

DIY spray paint doesn't seem to hold up too well if you intend to drive it in the NJ winters at all. Otherwise it's likely that sanding off rust and painting your bumpers will become a yearly ritual every spring.
 
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Not to hijack the thread, but I just got a new bumper and want to leave it in the aluminum finish. Would I just sand it clean it and apply clearcoat?
 
Not to hijack the thread, but I just got a new bumper and want to leave it in the aluminum finish. Would I just sand it clean it and apply clearcoat?

If it looks good 'as is' I wouldn't touch it.

If you are going to clear coat it you will need to scuff it up (be precise with your pressures to keep the grain in the same direction throughout), wipe clean with alcohol and quickly clear coat so it doesn't flash corrode.
 
If it looks good 'as is' I wouldn't touch it.

If you are going to clear coat it you will need to scuff it up (be precise with your pressures to keep the grain in the same direction throughout), wipe clean with alcohol and quickly clear coat so it doesn't flash corrode.

Typo on my end. It is bare steel not aluminum so wouldn't it rust if I left it as is
 
Expecting my dirtworx bumpers any day. How many coats of primer, top coat? Any additional coating? Any tips welcome. Largest paint project to date.

1. wipe down the bare metal with alcohol or acetone to remove contaminants. You don't want to sand them into the surface.
2. scuff up the surface with a green SOS pad or use sandpaper if you like.
3. wipe down with acetone or alcohol again
4. self etch prime 2-3 coats following directions on can for drying times
5. top coat 3 coats (2 light and one medium) following directions on can for drying times
6. if you want add a clear coat following directions on can
 
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Typo on my end. It is bare steel not aluminum so wouldn't it rust if I left it as is

Sorry, I mis-read, thought it said it was aluminum. Yes, it would rust if bare steel. I don't think you can just put a clear over bare steel. Find a decent aluminum color paint and follow steps above.
 
I don't think you can just put a clear over bare steel.
Not to hijack the thread, but I just got a new bumper and want to leave it in the aluminum bare metal finish. Would I just sand it clean it and apply clearcoat?

You can clear over bare metal, but results will vary, and I’ve heard of guys having to redo it multiple times to get it right. From what I've seen/heard, it's generally not very durable, and you really need to find a DTM clear. I have used Eastwoods diamond clear (DTM clear) on restoration parts with good results. It has held up for me for ~5 years now, but that's on an always garaged, rarely driven vehicle. I really don't suggest this for something that's going to see regular use.

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I use Dupli-Color Bed Liner spray as a topcoat for a lot of things like bumpers, roof racks, brackets, etc. They offer 2 different types. One has a heavier texture. This one has a lighter texture and is the one I use. BOTH textures are terrible as a bed liner but this one can be put to other uses.

Duplocolor Bed Liner Aerosol.jpg
 
Not to hijack the thread, but I just got a new bumper and want to leave it in the aluminum finish. Would I just sand it clean it and apply clearcoat?

You can get some that specially made for aluminum wheels that would be a good option- Read the instructions close some companies want you to go over it with a red Scotch-Brite pad to open the pores.
 
OK I’m not trying to sound like a know it all but to support my earlier post back in the day I worked in a metal fabrication plant-

There are a lot of cutting fluids, oils, soaps and release agents used in the process of fabricating metal to keep it from binding in the equipment and to prolong tool life - Washing things a couple of times with hot soapy water is a really good habit for anything that you plan on painting or resurfacing. Even if the manufacturer says they do all the cleaning ahead of time things get handled with human hands and skin oils and contaminants get on the metal... And in it.
 
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Hit it with a can of brake clean and wipe it off before applying your primer. Then shoot it with 2-3 coats of your favorite paint and install once it’s dry.

Sanding smooth surfaces before painting them has always been a funny one to me. People love to scuff plastic flares then casually ignore the unnecessary scratches they just caused from using too rough of a grit. If you think you’re giving it something to “adhere” to, you’re not. You’ll be repainting them in a 3-4 years regardless.