Working with Copper

[Chris Bacon]

Really?

[markzoom]

I'm just wondering what colour it would go in salt water. All the copper exposed to the sea that I've seen is green. M.K.

[The Natural Philosopher]

No, thats what it gives OFF,when applied to teh coppeer... but thats not waht the stuff IS.

[The Natural Philosopher]

Mm. I wrote that badly. Leaks go green very quickly. Condensation still greens, but less quickly.

I guess the condensation has Co2 from the air, whereas the hard water has calcium and or sodium carbonate (after softening) in it.

I can't remember the reaction routes, but I am fairly sure you need to go via copper or cuprous oxides: The air 'browns' the copper due to a surface layer of cuprous and cupric oxide? And then THAT layer goes to a carbonate in the presence of carbonated water.

I know that no copper that _stays dry_ indoors goes green, but it does brown up quickly.

[The Natural Philosopher]

You are right.

I suspect that is anoher reaction route again.

But copper UNDER teh sea does not...IIRC. It needs air...

[Chris Bacon]

Sorry, David, I've just had one of my infrequent looks at my e-mail, and I see a comment, so I re-open this to answer - outbound mail is currently TU.

To expand on my "Really?": they don't put lacquer on copper pipes to keep them shiny - it would seriously interfere with soldering, so tradesmen/DIYers around the country would go purple with rage!

Regards,

[Bill H]

Can you buy (or make) a more concentrated carbonic acid to speed up the verdigris process? Bill H X-No-Archive

[Frank Erskine]

Soda water.

[Ed Sirett]

or a 1:1:1 mixture of Calcium Chloride Ammonium Chloride Copper Nitrate.

Doubtless obtain pre-mixed from a supplier online.

[Steve Firth]

I have downspouts and gutters in copper, it hasn't gone green, it's brown and currently tending towards black.

[Aidan]

Sculptors' suppliers stock stuff to put a patina on bronze. I don't know if the same stuff would work on copper or if they do a formula for copper.

I heard that roofers would accelerate the growth of the patina on a copper roof by urinating on it, but I can't recall whether this was conversation was about this being a beneficial or detrimental effect. If it was just a long climb down to the toilet it may have caused uneven colouring.

[Tam]

I worked on a job years ago where they were doing a copper roof. When the roof was complete the plumbers went around the site with buckets for everyone to pee in. This was then poured and brushed over the copper roof to accelerate it turning green.

[The Natural Philosopher]

Be patient. It will go..

[<me9]

It depends on the pollutants in the air. Sulphurous fumes cause it to go black (copper sulphide), and the more normal CO2 will give a green copper carbonate colour.

[Steve Firth]

Currently five years old...

[Doctor Evil]

Liverpool must have clean air then, as the copper roof on the Anglican cathedral is green.

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[Andrew Gabriel]

Otherwise known as Taking the Piss.

Oh, more traditionally used to do the laundry...

[Owain]

In the tabloids yesterday that following the appointment of the new Pope, Eggs Benedict have been removed from Rangers corporate entertainment menu.

Owain

[Dave Plowman (News)]

They spray it with some form of acid to make it uniformly green immediately - I remebemer seeing this done to the dome of the art gallery in Aberdeen when I was a kid. One day the new roof was gleaming copper - the next bright green.

[Andy Dingley]

That's a bad idea for patinating copper. It gives you a rapid "green colour", but it's the wrong sort of copper salt. It won't give a stable colour, and it may even accelerate corrosion.