Just to look in a differant direction, I am in the process of covering the frame on our 66 Burb, and have been looking into the Eastwood products. From what I have figured out, the Rust Convertor is for something that is solid rust. The Rust Encapsulator, seems to be more for a minimal rust, bare metal, paint kind of thing. There are a number of reviews for it, and it seems to be extremely well liked, and not as severe or costic as the Por 15.