Rust is not a living breathing animal. There are products designed for rust protection and are not magic potions. They do not just cover up, they do work. For a successful repair you need to eliminate the rust because finish products may stick to the rust, but the rust does not sufficiently bond to the base metal and will not allow for a good moisture barrier. You can eliminate rust and prevent it in metal that has rusted through in area's, but it will not have the strength it had when new. Phosphoric acid removes rust, etches the metal in preparation for adhesion of top coats and converts it to a zinc phosphate which is proven to inhibit corrosion. Rust will not develope without moisture. This is where the so called magic potions come in. There are a couple of products on the market. What these products do is to seal the metal from moisture. With the absence of moisture you are assured rust will not (ever) return. This is from my 25 years experience in restoration and as a chemical sales rep. as well as dealing with over 500 accounts per month and asking them what works. Good luck with your projects and I hope this helps.
