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

https://record-wiki.win/index.php/Snow_Guards_for_the_Long_Wintertimes:_Customized_Copper_That_Keeps_Its_Pledge

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