[sbaert]

Unusual, but looks age related. Attack the problem now, while the rust is minimal, as once the cancer starts you can never fully get rid of it.

 

[sbaert]

Not "just paint" but a coat that is meant & intended just for this application. Here is one that is top notch, and cheap to boot.

Eastwood Heavy-Duty Anti-Rust in Black

Spray inside doors and rockers where painting won't be required.

www.eastwood.com