Por15 on surface rust on roof

[Micah Wells]

I've got some surface rust in a couple of areas on the cab roof. Could I use a por15 type product? If not, what do y'all recommend outside of a respray?

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[kennythewelder]

You have to remove the rust before you treat is with anything. Even navel jelly will work, but it needs to be as rust free as posable first. We use Ospho at the shop, and I used that when I worked offshore on oil drilling rigs. Por 15 will work, but again you have to remove the rust. If it was me, I would take a wire brush on a die grinder and get rid of all of the rust I could then treet the metal.

 

[Micah Wells]

@kennythewelder, thanks for the response. You wouldn't recommend using any of the rust to primer converters?

 

[kennythewelder]

@kennythewelder, thanks for the response. You wouldn't recommend using any of the rust to primer converters?

The rust to primer converters arnt near as good as ospho is. But if you do use a rust to primer converter, again clean off all of the rust first. As for what I would use or do, clean off all of the rust. Then, ospho, or navel jelly. Then prime or por15. Then paint of some kind. Keep this in mind. Primer is porous and will not prevent rust. It will just slow it down. In a short time, the rust will return if you dont put some paint down. Even rattle can paint is better than nothing. I like the rust-oleum 2X ultra cover over primer.

 

[MrPink]

you could but the correct way to do that is sand it down, rust converter(of any kind), primer then paint it.

 

[DerekTheGreat]

I repainted my roof last year. Had rust like that but like others mentioned I wire wheeled as much of it away as I could, sanded with 120 grit in the areas the rust was, shot etch primer over the same areas and then primer surfacer followed by primer sealer, base coat and then clear coat. Where there was still paint, I feather sanded. Chips and peeling paint were awful, but same principal there. I believe for feathering I used 240 grit and then 400 everywhere else. I wanted to keep as much of the original zinc phosphate and ecoat as possible. Came out decent and you can't tell there was rust before.

 

[deadbeat]

Make sure you pop that moulding out so you can get the channel clean as well, looks like rust is in it too.

 

[someotherguy]

As mentioned if you use POR15 you still have to paint on top of it. POR15 will not last in direct sunlight.

Richard