Cobalt nitrate is used as an undercoat and can be seen between the transparent patterns of cupric nitrate patinas. Patina application Bronzes are first blasted with fine glass beads to remove any oxide deposits and also to put a fine etch in the surface that helps the patina take hold. After blasting, the bronze is goldish in color and has a satin-like texture. Any areas that are to have a polished finish are polished before the patina is started. To begin the patina the bronze is heated with a propane torch.
Different temperatures can produce varied shades and textures from the same chemical solutions.
As the bronze is heated with the torch it radiates a different glow as the temperature increases. Experience in application tells the patina artisan when the proper temperature is reached. Different methods of application vary the shade and texture produced by the chemical solution. Patterns are created by spraying streams of chemical solution with the atomizer bottle. The heated metal evaporates the chemical as it runs across the surface of the art.