CURING POR 15

ch1ll said

all paint will peel when coated to smooth metal, the surface of the metal needs to be roughed up with scotch bright or sand paper for the paint to have something to hold and stick to.

my experience with por 15 has been that it did not stop the rust.

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I agree. All primers need tooth on bare steel. Paint manufacturers recommend #80 under epoxies and other DTM (direct to metal) products and the bare metal needs to be coated within 8 hours or microscopic rust will be too much after that. Low humidity conditions will widen the 8 hour window. POR15 encapsulates, it does not "treat" the rust like conversion products. 2 totally different products.

Por15 is tough stuff. It's catalyst is moisture. 40% - 70% is best. If you do not encapsulate all of the rust, the rust will continue and start to creep under the coating. Rust "converters" like Rust Mort and Ospho use the rust to turn into another product that becomes a hard black primer that needs to be neutralized and sanded before topcoating. I could cut and paste a bunch of technical terms and links but I'm trying to put this in a nutshell. I hope this helps.

Like most subjects, there is a ton of info out there about all of this. The OPs problem is not enough humidity (catalyst). Humidifiers have been suggested but I do not know if that will help or not. Too much humidity is a problem too and just like other product the mixing ratio has to be correct. Its just harder to control when its the humidity instead of a mixing ratio in a cup. Too much or not enough catalyst in an epoxy primer can cause drying problems also.