Procedure for bumper rust removal and protection

Bmachine

Bmachine

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I am getting a set of bumpers that have some rust on the inside. I have read lots of threads on the forum on the subject and I want to make sure I do this right. I am not after a concourse result. Just a basic clean up and protect.

Penetrol and POR-15 are names that keep coming up. But I am unclear as to the different roles that each play. Do they work together? Would something like this scenario make any sense?

1. Remove loose rust with wire brush or wheel

2. Use Loctite Naval Jelly to neutralize what is left.

3. Apply Penetrol liberally

4. Paint with POR-15

Thank you.
 
Ohmess and I have both used Evapo-Rust with excellent results. Takes a few days of full contact, but it truly dissolves the rust, leaving a clean steel surface.
I bought a quart, and after a couple of uses, bought another 3 qts - JUST TO HAVE ON HAND!
 
POR-15 ideally needs rust to attach itself to and they recommend their topcoat before you can paint over it or your paint won't stick. I would save POR for only the rustiest situations.

Lightly sand away any rust, clean, apply a good etching primer and then paint, you are good to go.
 
Thank you Gary and Chris.

@Gary: It sounds like Evapo-Rust needs the part to sit in it for a while. Since a bumper is pretty big it would be near impossible to "bathe" the whole thing it unless you have gallons of the stuff. How do you guys deal with large objects?

@Chris: This bumper is coming from Hawaii so i fear it will be pretty rusty. Would you use the POR directly onto the rust? Since this will be strictly for the inside of the bumper I don't need to paint it except for a protective coat. Does the POR need to be covered by their topcoat in that case? Or can I / should I use Penetrol on that of that?
 
I would still sand and then prime and paint. Nothing sticks to black POR-15, inside should be grey color I think.
 
Bmachine,

You can just paint the Evapor-Rust onto the rusty areas, then cover it with thin cling wrap. Pull the cling wrap off every day or so and repaint/recover. That works just as well as submersing it, but may take about 20% longer is all.

Alternatively, I've seen some good reports on 'Rust Bullet'. I am using it on some rust areas on the front seat bottom frames (and springs) that were a bit rusty. Treated the springs a couple of times with Evapo-Rust first, but it was impossible to stop the evaporation, so it didn't dissolve the rust as well. I sprayed with a Harbor Freight low pressure high volume spray gun with a 1.8 tip. Worked well, and the company says there is enough flex in the paint that it will not crack when the springs flex. It is a metallic silver in color, and can be sprayed or brushed on. Takes two coats within about 3-6 hours depending on drying speed.
 
Evaporust recommends a wet cloth left in contact with the surface overnight, covered in plastic wrap to prevent evaporation. I have not tried this on my bumper yet (chasing more electrical gremlins after my voltage regulator went and shot 19 volts through the car for a while), but plan on doing this.
 
Bumper

I'm about to go through this process using POR15, after treating any rust with their metal prep and ready product. I'm planning to lightly sand anywhere I'll be painting with POR15 to give it a bit of a key, both on the back, and on the front of the bumper behind the rubber. I've got a little rust underneath the chrome around the holes where the rivets and metal mounting strip were in contact, but you won't see it when the rubber goes back on.

My question is - I have new rubber mounting strips, which I'll be mounting with new rivets, I'll probably coat absolutely everything you can't see with POR15 after I've mounted the metal strip, before reinstalling the rubber, to protect the new rivets and mounting strips. also, I'll also be cleaning and going over the whole rubber strip with Gummi Pflege while it's off. But how about putting some kind of sealant between the rubber and the bumper to stop water ingress ? obviously water gets trapped in there which is why these things rust so badly. I know you can get stainless strips now, but I didn't get those !

Sorry if it doesn't make sense, it's hard to explain.

One other question, I'm ordering new fasteners from Walloth & Nesch, would it be a bad idea to use copper grease when mounting them ? reason being I'll need to remove them again for painting next year.

Thanks for any tips - I've already had a good read of previous posts which have been extremely helpful, as usual.

Damien
 
Top coats will stick to POR 15 if you apply them while the paint is still tacky. Once dried you need their tie coat primer. Unless the part is exposed to UV, there is no need for a top coat. I have some old parts that have been exposed to a few salty winters with POR 15 and then trim paint and have held up very well. . Ideally POR 15 is a three step process. Marine Clean then their acid etch .You can apply it to bead blasted and clean metal if you etch it first with their (or some other?) chemical.
 
I'm just about to reassemble my bumpers following rust treatment and fitting of new metal strips. I'm considering using some kind of sealant to stop water getting in to rot the new strips, has anyone done this ?
 
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