I marvelled just how patination is both art and chemistry; controlled oxidation, acids

https://www.scribd.com/document/1041762894/Cupolas-with-a-Century-in-Mind-The-Instance-for-Hand-Fabricated-Copper-Craft-224458

I marvelled just how patination is both art and chemistry; controlled oxidation, acids, and waxes produce living coatings that progress with weather yet continue to be protectively sealed.