|What is Patina|
As a general term, patina refers to the change in an object's surface resulting from natural aging. (Patina preservation is the reason to avoid all but very superficial cleaning of old objects.) In bronze sculpture, patina specifically refers to the surface of the bronze itself often altered by the sculptor with acid or the application of other chemicals.
Bronze with 24K Gold Patina
Why does patina matter on a bronze?
Alas, no. One has only to compare
patinas on Rodin bronzes. Look through the patinas of the fine photos
in this Boston College Online
Rodin Exhibition, then study some of the newer Rodin bronzes on the
auction block. The patinas on these later re-castes are often times as
subtle as black shoe polish.
A light touch is key: Some sculptors of the American West employ tinted highlights, and certain contemporary bronze sculptors use high color. Unless these accents truly reinforce the intent of the piece, color can degrade into kitsch