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Copper Oxidization - The Thermal vs Chemical Causes

 

High I'm an Electrical Engineer within the Power Industry. Do you have any ideas on the following: I have observed surface oxidation on the copper of a set of electrical bus-bars. The colors observed would indicate that the copper has been subjected to temperature though adjacent components would not support this above 170 °C. The oxidation is very similar to that of tempering effects displaying the colors green blue and purple migrating along the length of the bar.

How could this oxidation occur other than heating? If it was temperature related, at what temperature would you expect this discoloration to occur at. What book reference would you recommend to understand the issue further?

Dave Kent
- Rochester, Kent, UK

I would like to find out the mixture amounts per substance (vinegar and salt) to oxidize copper wire. All information on the subject would be appreciated.

Thank you,

Annie English-Hogg
visual art student - Ireland