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

https://www.scribd.com/document/1039869947/Salvo-Metal-Works-and-the-Truth-of-Copper-Personalized-Chimney-Shrouds-that-Endure-183965

I marvelled how patination is both art and chemistry; managed oxidation, acids, and waxes produce living finishes that advance with climate yet continue to be protectively sealed.