Rust converter/etch primer/catylzed paint or epoxy primer

[laserjock]

Okay guys. Yet another question about fighting the rust monster. I've done a lot of reading on epoxy primer. It doesnt like most of the metal prep treatments (most of which involve phosphoric acid in some form or another). I'm about to strip my truck down to her knickers and I plan on sandblasting the frame and underside of everything at a minimum. There are always those places that are hard/impossible to get to. I'm thinking like a POR type metal prep in spray form for the nooks and crannies. I've had some success with that in the past on surface rust. Follow that up with an acid etch /rust prevent primer like the implement stuff from tractor supply then follow it up with the catalyzed black in that line.

The alternative is sandblast the best I can and then prime it with epoxy. I've always been freaked out by putting epoxy over "questionable" metal. A lot of guys swear by the epoxy and I can see why but just sealing the rust up without "neutralizing" it seems risky to me. Maybe I'm just paranoid.

Which sounds like the better route to slow down the rust monster?


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[94f450sd]

About 7 years ago i used a rust converter made by dupont on my car.followed by dupont vari prime self etching primer followed by dupont urethane primer.last time i seen the car it sat outside unpainted/uncovered for 5 years.nothing ever came back.


Im in the process of doing a 71 chevelle now.taking care of the vinyl top rust the same way except im using SEM rust seal.

Ive recently used the por15 paint.the formula or something is different.used it when it first came out,walked around with stained hands and face for 6 months.stained the shop floor.2 weeks ago i washed it off in the shower with no staining of skin.

 

[TahoeTom]

http://www.hotrodders.com/forum/ospho-solution-rust-removal-175465.html
Here is probably more than you wanted to read on the subject. There are lots of opinions and approaches. This thread is one guy's method that he has used for years. A popular epoxy used by a lot of the guys on this forum is SPI (Southern Polyurethanes). According to SPI their epoxy shouldn't be applied over rust conversion products. This guy does it without issues. Maybe because he sands the metal to remove excess dried Ospho before epoxy. He doesn't rinse with water as some rust converters require. I don't want to rinse with water to deal with rust, as it seems like it would just cause rust. A product I have been using is Picklex 20, but it is expensive.

 

[junk]

I personally have had good luck with Epoxy Primer. I've used a rust convertor called PHIX and put epoxy over it. I believe most acid etch primers are more picky about what they go over and what goes over them. I believe they need to be shot over bare metal. No existing finish or bondo. Epoxy as the first round of primer works well for me. I would say make sure you shoot either Urethane or topcoat over it during it's recoat window. Basically a Wet on Wet application. Epoxy primers are typically hard to sand so you don't want to have to scuff them before recoating them.

 

[laserjock]

Wow. Got through about 3 pages of that ospho thread. Lots of info there. I am thinking of going with the SPI epoxy. I've done a lot of reading and not really heard anything negative about it. The implement paint is somewhat attractive for the frame and running gear because I can brush it on and it not look too bad. It's also not too finicky about what it sticks to. Easy to touch up underneath too. It's catalyzed so it should be better than regular old rustoleum. My buddy used it on his antique Porsche and it turned out pretty good. No data point on longevity yet but I guess we shall see once I get it apart. Maybe just black epoxy primer shot on everything would be fine. Guess it wouldn't have to be top coated on the undercarriage.

If I pull the cab like I'm planning, it will get epoxy once its all cleaned up. I'm replacing the front sheet metal and doors so they are all going to get primed and painted fresh. Bed will get cleaned up underneath and get epoxy for sure.

A wise man once told me there was no right or wrong...only consequences. Pick something and go. I'm bad about over analyzing. I guess that's the scientist in me.


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[freebird01]

ive had very good luck with SEM rust shield as a chassis paint and under body paint. it passed the same salt spray test as POR-15 but its half the cost and you dont need all the prep like POR-15

 

[laserjock]

I'll have to check that out. I looked at POR 15 paint but wow, they are proud of it.

 

[freebird01]

i had a truck frame done with it that sat outside in the weather for 2-3 years uncovered and it was still shiny when i cut it up and scrapped the project...i bought it through summit racing

 

[warmblood58]

My e350 van has rusty rain gutters, everywhere else fine. I have used POR products before and have product to use up. I think I will scrape, degrease, etch, POR putty (epoxy putty) and then seal with POR 15, then use their self etching primer so I can paint over gutters with conventional paint . . . hope that will work!