I've Heard of Painting between the lines but, can this be done?

like it was mentioned, por15 just seals and it dont stick if there is a lot of rust

you gotta get to it somehow

p.s. dont take a bath in that stuff it sticks to / soaks into your skin for 3-5 days and will not come off. says right on the can once dry there is no known solvent

my daughter didnt believe me she is a chemist and guess what, she tried everything she could think of and it didnt come off lol

if it's still wet rubbing alcohol removes it

but you have to find a way to clean that spot. then squirt it. if you can see it make some kind of whirly scraper with a drill and coathangers or something and get the surface rust off the best you can