Zinc Phosphate primer - Painting Exterior Metals

[dhutch]

What surface prep for painting old steelwork?

I am looking for solution to painting rusting and half painted exterior steel work as I have some metalwork, in fact a small excavator arm, that I am restoring and need to repaint.
- Fully washed and degreased but a mix of rust and oil paint.
- Needs to be mechanically derusted to remove loose paint and rust.

But then what do I paint it with?

Dug out some past posts which suggest using phosphate primer which having done a search, I like the sound of. How much of the rust to do you need to remove before applying the primer. I cant get it all back to bright steel, but I can give most it a good go with a wire brush in an angle grinder, and if I can borrow back my compressor a needle scaler, all bar a few bits where we might be down to chipping of as best I can with a screwdriver and squirting oil in there when it starts to rust through in a years time!
- Is that enough do we think?
- Anything more to add?
- Recommended brands of primer?

Past posts:
About outdoor metal railings:

I would generally use Zinc Phosphate primer rather than an undercoat for most stripped back railings, followed by a good quality one coat gloss system.

About outdoor metal stairs:[/]

What often worries me in these situations is the slip factor, Dulux do a Trade Metalshield Gloss and Satin and are superb products. You will have to remove all loose and flakeing paint and sand the existing paintwork, then the exposed metal areas should be primed with a Zinc Phosphate primer followed by two gloss coats.

Dec

Thanks in advance.


Daniel