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

https://reidjgcr153.image-perth.org/dormers-you-can-rely-on-the-honest-aging-of-hand-fabricated-copper

I marvelled how patination is both art and chemistry; managed oxidation, acids, and waxes create living coatings that develop with climate yet remain protectively secured.