A Bronzer can also be relate to the printing trade. The trade has often used real gold leave to embellish leather hard backed books. This was a very expensive method and highly crafted.
Bronzing was an easier and cheaper method particularly used on greeting cards. The area to be bronzed was printed with a slow drying yellow base ink, the printed sheet then passed under a curtain of gravity feed bronze powder which stuck to the ink. The surplus was shaken off before a series of oscillating brushes polished the bronze to a lustre. Inevitably there was always a gold cloud surrounding the press when it was operating, covering everything in the machine room including us printers. The bronzing machine was a mobile piece of equipment which could be attached to various printing presses. I occasional had one attached to my machine, we got 7/6d extra allowance per week it was called a milk allowance and was expected to help wash the bronze from your throat. Some days I used to walk out looking like 'Shirley Eaton' from Goldfinger. LOL This was in the days before H&SE.
I guess it could have been a similar process in the jewellery trade i.e. a base lacquer applied to the parts to be 'gilded/bronzed' and then dusted with bronze powder before burnishing.
I dread to think of the health implications which some of us have worked under.
