SoreFeet is right, however, if you go into this business:
Clean as much rust off the steel as possible, by scraping with a knife, manual or powered wire brush, and/or sanding. Rust converter does turn ferric oxide (rust) into ferric phosphate, which protects the metal. Using a good primer is more important for subsequent protection than whatever the top (color) coat is, so don't omit a coat of primer.
I'm beginning to think that Trek paint was ***t. I've posted previously about my '82 frame that's seen extremely little use, and yet the paint is very chippy. It has some bubbled areas near/on the BB, and bottom of downtube and also at the base of the head tube. Well today I went at them with a knife, and all I can say is: "A Friday-afternoon paint job, after lunch at the bar!" In the bubbled areas, the paint would actually chip up in sheets, with practically no adhesion. It didn't even look like there was any primer there.