rust

I've recently become a huge fan of Fertan - it seems to do what it claims to do.

There used to be something based on FishOil. Waxoil dries out and needs re-doing periodically.

Hmm, I had some paint on stuff, but once rust has started, it seems to just harden it and slightly slow its progress. my guess is that the open end of the coating is still open when this happens. I had a frame used for an aerial mast lift/lower device which was supposed to be galvanised then nylon dipped but it still started to rust around where the bolts went. Brian

The coatings I've had most success with I have bought in France. One which seems difficult to obtain now is "Vernis pour Rouille", literally Varnish for Rust. It's just a clear varnish which is very runny and seals all the pores and indentations of the rust. I've used it on some bare reinforcement rods for example and they're still just as when they were first coated.

The other coating I have used is more widely available, it's Owatrol. It's very similar to "Vernis pour Rouille" and seems as good. It does take longer to dry out thoroughly though and never seems to go as hard as the other.

I have successfully used phosphoric acid in the past, but you need to neutralise it after it has killed the rust.

But that's for cleaning and removing rust before coating with some sort of rust preventive. If you just use phosphoric acid and then leave things it will rust even faster I think as you've exposed the bare metal again.

Iron phosphate rather than bare metal.

I used some kind of rust converter on some iron garden furniture and then painted it. Not a complete cure, but its looking better than it was.

Iron phosphate from iron oxide actually. Turns rust into iron phosphate. It wont rust more because iron phosphate is a tough layer and any fresh rust will end up as phosphate as well.

There was a prodct called Kurust which was solvent-based and quite useful but since 2010 it has gone water-based so cannot be used if there is any hint of existing paint or oils.

Phosphoric acid is soluble and can be washed off, leaving clean iron phosphate.

yes it used to be good