I read the POR 15 instructions for trunk and floor pan restoration, but unsure about one thing. It doesn't say anything about removing old paint or primer. It just says to wire brush to remove loose particles, Marine Clean and then metal ready, then POR 15. Is this correct?

Also, my floor pan is pretty good, some rust, but I wanted to clean it up as well. Again, I see mostly red oxide primer. Do I just do the steps above and POR 15?

Please help.

I don't think the Metal Ready will etch the metal properly if it doesn't get to the metal. (paint in the way)

They say that the POR will stick to old coatings but your ideal surface would be rusted "seasoned" or etched bare metal. They say you won't get the full benefits of the coating without it coming in direct contact with the metal.

IMO, knock off the loose stuff, etch any clean bare steel, ruff up the rest and lay the stuff on.

The general commentary I see on painting over finishes with POR is that the more of a painted or finished surface it is, the less reliability POR will have.

The ideal finish, as already stated is something along the lines of a "roughed up" bare metal. Theoretically, it can be applied directly over rust, but on that note, you're not repairing anything, you're just covering it up, and that just ain't right!

So, to answer your question, get rid of as much of the existing finish as you can and apply POR over bare metal that has plenty of "tooth".

Bare metal, metal ready, POR, Tie-coat priner, truck spatter paint,(or if interior floors, red priner.