Hi We have an internal metal staircase frame that needs a top coat that is hardwearing. We would have got it powdercoated but it was too hard to move in the end. It is not too exposed as the treads are all wood, but something close to the powdercoating would be good. It has a highbuild thinners based two coat primer on it at the moment. Kind regards Duncan
Assuming the existing coating is a 2 pack epoxy primer and is beyond it's overcoating period, you would need to mechanically abrade the surface to create a key before applying 2 coats of Rust-Oleum 9200 Rust-O-Thane.