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

https://www.scribd.com/document/1040872073/Finials-That-Finish-Well-100-Years-of-Copper-Integrity-143726

I was surprised just how patination is both art and chemistry; controlled oxidation, acids, and waxes develop living coatings that advance with weather yet remain protectively secured.