Anyone here that knows about paint? I tried to paint a chassis having a unknown paint. Mostly one coat that has peeled away from the metal. I'm using some oil based universal tractor paint. The oil based would not bond, it turned to a gel like rubbery grease. 2 days later and it is still spongy and soft. All that damn sanding and elbo grease down the tubes. Any clues as to what happened?  I sure don't want to go through this again.   Thanks...

Don't know why your paint is peeling. Did you use some kind of a spray on chassis prep/cleaner and not rinse it off soon enough? I know some metal preps require thorough rinsing, and should not be allowed to dry on the surface. This causes (i think) metal oxides to remain on the surface that are high in PH. 

 Next time use either POR15 or KBS chassis paint. Strongest stuff known to mankind on bare or rusted metal. Just follow the directions closely for prep. JUST DON'T GET ANY OF THE PAINT ON YOUR SKIN......USE GLOVES!!!!!!!!!!!!!!!!!!!! If you go tothe  KBS website they explain exactly how and why to prep metal properly or else you will have peeling.

It sounds like a prep issue. Silicone or oil on it. A good etching primer may be needed. Primer sticks to metal, paint sticks to primer, paint does not stick to metal very well. I found that Rustoleum is good for just about any application from their spray bombs. You might have defective paint that lacks enough activator or did not have an activator in it.

The frame is a 99 Olsen, the OEM paint was mostly peeling way from the steel. I sanded/buffed as best I could and used rustlium brown primer on the bare spots. The problem is where the new paint is going over the OEM paint. Before painting I wiped it down with mineral spirits. The new paint looks okay where it was on primer, but not where it went on the old paint. Maybe I should have sprayed primer on the whole frame.

Testing the new paint on some various samples is a good idea. I'll try that . It just might be this new paint. But whatever the source, I sure got a lot of extra work to do now.   Thanks for the hep & ideas.

There are so many different paints out there it's easy to run into problems. The fact that the new paint does OK over the primer says the new paint works well, it just doesn't want to play nice over the oem. It sounds like sanding the oem paint opened it up and the new paint is attacking it. Is this new paint in spray cans? Brand?

Could the original coating perhaps be powdercoated?

Yes I'm pretty sure it was powder coated, and through the years it has seen some spray can work. The areas that had weld seem to have not weathered well. The cage and longer tubes look decent, but that is the areas that had the worse reaction to the new paint. The primer I used w Rust-oleum red lead and the paint was Valspar tractor & implement.