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Chrome plated bronze is going black in swimming pool

1998

Dear Colleagues

I have a potentially interesting little problem which I feel sure that someone on the list will have encountered previously. It goes like this:

1) Structure is an outdoor swimming pool (In California, so a site visit would be nice, though unlikely!)
2) Components of concern are lane marker anchors grouted into the pool wall.
3) Materials chrome plated bronze (I don't at this stage have a composition)

The problem is that the plating, much to everyones surprise, is going black.

Has anyone come across this problem before and or does anyone know of anything in the literature that I might be able to get hold of to refer to.

I think that the following are fair assumptions:

The anchors are wetted by the pool water (either permanently or intermittently) and the plating was not supplied black.

I look forward to your replies.

Regards

Graham

Any views expressed are entirely my own, not those of Ove Arup & Partners.

Graham Gedge
- London, UK

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I'll bet that the oxidizing power of chlorinated water is the agent which is causing the black oxidation of a metal or an organic. But I would be doubly curious about the composition, because it doesn't really sound like a chrome 'thing' to turn black that way. I wonder if it's plated with something "just as good as chrome".

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Dear Graham ,

I agree with Ted , but who specified chrome in the first place , even with the toughest of specifications being adhered to it is not a finish I would have considered "suitable" fot the environment , in such an environment where "Free Chlorine" is present the only real long life solution is a high nickel alloy such as "Hastelloy C"

regards

John Tenison - Woods
- Victoria Australia
1998