Coating your surface rusted floor pans with POR-15 is a great idea. First step is to scrape away all the old surface rust with a wire brush. After the dust/rust particles have been vacuumed up, thoroughly clean the surface with POR-15’s Cleaner/Degreaser. Next comes the Metal Prep (also from POR-15), then you’re ready to apply the Rust Preventative Coating.
Tip: Use the cheapest paint brush you can find to apply the POR-15 Rust Preventative Coating, as it will be destroyed after one use. One coat of POR-15 is all it takes to stop those old surface rusted areas in their tracks.
Once your floor pans are treated, they’re ready for insulation and carpet!