Quote:
Originally Posted by jeremy_haak
They start of a bright copper colour, but quickly fade to a brown colour that lasts much longer.
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The oxidation of shiny bright copper doesn't occur fast enough for many old time roofing contractors, and so they used to brush horse urine onto them to speed up the process. They go from shiny "copper coloured" to a dull orangey-brown to a browny-green and finally to the classic dull green. There isn't really any black in the sequence.