I marvelled exactly how patination is both art and chemistry; regulated oxidation, acids

https://cesarfksk421.yousher.com/100-years-of-patina-the-designer-s-case-for-hand-fabricated-copper-cupolas-by-salvo-metal-works

I was surprised how patination is both art and chemistry; managed oxidation, acids, and waxes develop living surfaces that progress with weather yet stay protectively sealed.