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

https://page-wiki.win/index.php/Dormers_That_Don%27t_Deceive:_The_100-Year_Performance_of_Custom_Copper_by_Salvo_Metal_Works

I marvelled exactly how patination is both art and chemistry; managed oxidation, acids, and waxes develop living coatings that advance with weather yet stay protectively sealed.