I was surprised just how patination is both art and chemistry; regulated oxidation, acids

https://blogfreely.net/frazigkbpn/h1-b-the-reality-in-the-patina-why-custom-made-finials-in-copper-are-the

I marvelled how patination is both art and chemistry; regulated oxidation, acids, and waxes produce living finishes that progress with weather yet continue to be protectively secured.