Hi @Steve5, I 100% agree with @DIYGnome that this is swarth left on the roof. The rusting is on the paint layer; it hasn't penetrated from beneath. ...
Hello @Steve5 these products (or any of your choice) claim to be designed/intended for use on painted metal (like Colorbond)A rust converter productht ...
@andekara Don't be afraid - it's not rocket science! You can do it easily. If you're worried, practice on a small pieces of wood first. you can ding i ...