Adsorptive Coloring of Anodized Aluminum by a Spray Process.

Certain shades of color are employed to only a limited extent, and only small orders are received for a given color, thus setting a problem in terms of the usual method of coloring anodized aluminum in immersion baths. The spray process is an innovation which is also applicable to the coloring of items of intricate shape. All that is needed to operate the process is a spray cabin plus a number of storage vessels holding various coloring baths and connected by pumps to the cabin. Spray time, temperature and concentration of colorant correspond to those employed in the former immersion process. Main advantages are: (1) the smaller volume of the coloring bath required; (2) the flexibility afforded by rapid changeover from one coloring solution to another; and (3) the smaller floor area occupied by the system and the possibility of siting the coloring bath storage tanks away from the spray line.