Seems like there is a lot of misinformation on what POR 15 actually is. First it does not react to rust, it dries in the presence of moisture and forms a seal to keep the ingredients needed for metal deterioration to continue. Effectively moisture is a catalyst similar to how a two part automotive Urethane works. It is far superior at holding out moisture than a single part primer and Rust-Oleum the same that a modern two part urethane paint is far superior to an old air dry enamel. One note. POR 15 contains iso- cyonates. You need to use a respirator when using with plenty of ventilation and should use a supplied air type. I spray por 15 after properly prepping the metal, just like any other paint product. The final product is only as good as the prep.