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

https://www.scribd.com/document/1042186110/Snow-Guard-Truths-Copper-s-Unequaled-Longevity-in-Alpine-and-Coastal-Projects-173583

I marvelled just how patination is both art and chemistry; regulated oxidation, acids, and waxes create living coatings that develop with weather condition yet continue to be protectively secured.