Rusty Angle Bead in Condensation-Prone Bathroom

[Steverob]

I have a rusty metal plaster angle bead in my bathroom on the window frame. I have rubbed the paint off, sanded the beading to bare metal and applied rust kill products, oil-based primer but the rust returns. Most recently I tried Jenolite DirecttoRust spray paint in loads of layers but the rust was poking through after just three weeks. This was disappointing given the paint is intended to kill rust.
I know others have asked the same question - has anyone found a good solution to this problem that doesn't involve ripping out the beading and starting again? I've been thinking of apply a thin coat of epoxy resin after sanding down, or trying a thin layer of white vinyl and painting over the top... Thoughts?

 

[opps]

When you say epoxy resin, which product specifically are you thinking of?

The beading would have had a galvanised finish. Sanding it would have removed the galvanised finish. That said, it you have rust, the galvanising had failed any way.

It is difficult to tell if the rust is the result of condensation or damp in the plaster. And the damp in the plaster could be a result of condensation.

 

[Steverob]

I'm not thinking of any particular resin: just something that flowes and will make a good seal. The galvanising had already failed before I sanded it. The rust is being caused by condensation I am pretty sure.

 

[GhostIntMachine]

You may need to bite the bullet and pull the rusty galvanised beading off, replace with stainless steel or plastic beading and reskim the corners. i noticed on a recent (domestic) job.that the plasterer who came to skim the walls brought plastic beads and BZP screws with him - the ensuite was being enlarged but still had areas of plasterwork above the tiled areas.