Gents

Starting to do a little work on my 70 Cutlass. Had it up on the rack today and really looked over the frame and underbody areas. The frame is real solid, but has a scale of typical surface rust all over it. Also, some seamed areas of the under body have some surface rust. I have no experience with POR15, is this the best product to use if I wire brush these areas and paint them over? I am not, and won't for a long time, doing a "frame off" even though that would be the best way to handle this. Just need to get somewhat of a handle on stopping the rust from getting much worse. Seems to me the last time I had my hand in an old car (late 80s/early 90s) there was a product that you sprayed on rust and it turned it black, meaning it was being neutralized? Is there such a thing?

Looking for recommendations-undercoating, paint, or POR15.

Also, how tough is POR15 to use? I haven't looked into it at all yet.

Thanks for any tips.

 

I don't have a lot of experience with POR15, but I don't believe it will convert the rust. Use a wire wheel, then a rust converter(the stuff you referred to that turns it black) & then paint it. The rust converter is basically a phosphoric acid solution that eats away at the oxidation. I've used all kinds & one of the most effective I've seen is actually available over the counter, I got some at auto zone. I believe its made by Kleen Strip.

 

I have heard that POR15 IS the best to use. They have a good website at POR15.com. Some of their paint can be applied right over rust (after the loose stuff is removed).

They also have "chassiscote black" that can be applied that mimics the factory semigloss (but is too shiny IMHO.)
If you look through some of the pictures in my link below, you can see some before and after results. I used the standard clear and the chassiscote. This was my first experience with POR15. I did not use all their prep chemicals, as I cleaned it all with other stuff. The directions even said some of it can be put on right over rust. Bare metal may be another story. Download their instruction sheets and go by them.

Use cheap disposable brushes, as cleaning them is impossible. Wear thick nitrile gloves and old clothes. If you get it on your skin, you will have to wait 2 weeks for it to wear off. It is like painting with epoxy. The fumes are not too objectionable and do not accumulate too bad in an enclosed garage (though I would not recommend that.)
If you get POR15, try getting the small cans - they are convenient.

 

I agree with Rob, the way POR15 works is that it seals out all possibility of external water intrusion, it will not convert the rust however as was stated. A possibility is to use converter, then topcoat with your favorite enamel to make a hardened exterior shell. I have used both products but not together.

 

Also keep in mind that POR is not UV stable and will turn chalky over time if not topcoated.

 

Thanks for the advice. I think I will use a rust converter everywhere I can get to, after wire brushing/wheeling. Then just hit it with some decent paint.

Is there any reason not to use an undercoating along the frame areas, and the underbody? Or, would paint be a better way to go? I don't know if the typical undercoating in the spray cans is all that good of a product.

Thanks again.

 

A rust converter will neutralize the rust making it inert. As stated a rust encapsulator will seal the rust preventing further exposure to moisture. POR 15 is a type of rust encapsulator.

A rust converter is not a good idea to use if you get down to good clean metal. It will not make a strong bond to the metal. Also most of the rust converters require using an oil based paint for the topcoat. Using anything other than an oil based paint will probably bleed through.

Three rust encapsulator products are POR15, Eastwood Rust Encapsulator, and Rust Bullet. The one downside to POR15 was mentioned in this thread, it is not UV resistant.

 

i sprayed my entire 65 olds dynamic 88 convertable with por 15. i striped the car down and sprayed the under body, the top half, fender wheels etc. everything i could except the outer body and dash of coarse. it is great stuff. once it hardens you cant chip it or scratch it. it drys in a gloss finish. all you have to do is run a wire wheel or wire brush over it to clean the loose stuff off, and paint it. you would want to cover all your plugs, wires etc. its some of the best stuff i have ever used. caution make sure you wear rubber gloves and a resperator and have good ventilation. once that stuff drys on your skin. it does not wash off, it wears off!! i found out the hard way. it took about a week to week and half. before it went away. chris

 

I have also had great experience with Por15. As long as the metal isn't totally cancer rotted & soft, Por15 is a fine product to use. It hardens to a very solid surface. I have only used the cans & brushed it on. I didn't know spray cans were available.

Where did you find the spray cans?

 

THEY DONT MAKE IT IN SPRAY CANS THAT I HAVE EVER BEEN ABLE TO FIND. I WHICH THEY WOULD. I USED A CHEAP SRAY GUN FROM HARBOR FREIGHT.

 

It's not available in spray cans...one good reason being that the product, being a urethane paint, contains ISOCYANATES....bad, bad stuff. AT A MINIMUM wear a GOOD respirator (something like a 3M Paint Spraying Respirator---not just one of those white fabric thingies) if you are spraying it and use a paint booth or a place with good air flow around it.

 

found that out the hard way. first time i sprayed it. i was not thinking and did not wear a respirator. ended up in the er a couple days later with respirtory infection could not breath
had to take medicine for awhile. good stuff, but bad stuff!!!!