rust treatment

Jun 19, 2008 7 Replies

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Fred 18 years ago

Hello,

I know you can get a black "paint" to paint over rust, but how does it work and is it any better than using normal gloss paint? Presumably forming a barrier to stop water getting in is half the battle?

The one I have seen is bizarrely water based, I would have thought water is the last thing you want to apply to rust! I know they are not quite the same but the Ronseal and Hammerite metal paints that are supposed to stop rust forming in the first place require a special solvent, don't they.

Thanks.

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meow2222 18 years ago

The best rust treatments contain phosphoric acid in water. This converts existing rust to a stable compound (iron phosphate I guess).

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Martin Pentreath 18 years ago

Sounds like Coca Cola to me. At last, a use for the stuff, I certainly wouldn't risk drinking it.

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The Natural Philosopher 18 years ago

Neither water nor air cause rust. Its both together. Or water plus some other oxidant like whatever seawater has in it.

Eliminate either one and you are on a winner.

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Dave 18 years ago

But doesn't coca cola rust/rot the gut? I wouldn't risk drinking it either.

Dave

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meow2222 18 years ago

far too weak unfortunately

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Rod 18 years ago

Ah - but our CC doesn't contain high fructose corn syrup (like it does over there - but not the passover version IIRC).

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Martin Bonner 18 years ago

The oxidant in sea-water is just dissolved or entrained air. The reason sea-water is so powerful at rusting is that it contains chloride ions which either make the rust layer more permeable, or catalyze the process (I can't remember which now - it's more than a quarter century since I did Metallurgy!).

Quite - which is why the Titanic hasn't turned into a pile of brown sludge - the air can't get to it, so it doesn't rust.

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