A chemist told me rust does not spread. The top of my refrigerator gives me some doubt. It’s covered in these spots. The center of every spot is a small break in the paint, but the rust all around those spots is on top of the paint.

  • The conditions for rust would be difficult to have but only have them at a single point. The conditions cause rust, then cause more rust, but because of the conditions and not because the rest is already there. In your case, once paint cracks (even pinhole sized), conditions cause rust, which causes more paint to come away from the surface so the conditions for rust touch a larger area.

    I’m not sure how to implement it in this case but you might have luck with using something like this to prevent further spread: https://en.m.wikipedia.org/wiki/Galvanic_anode