The conditions necessary for decoration in bright copper-zinc alloy plating are uniform color tone, high brightness, and thick plating layer. This paper describes the studies on addition agents to the copper-zinc alloy plating baths for satisfying these conditions.
Addition agents to cyanide plating baths were divided into the following two groups, according to their actions. One was a group of brighteners giving brightening action and the other was a group of color controllers giving uniform color tone. It was found that As and Se belong to the former and ammonia and amines belong to the latter.
Color controllers were not found in these addition agents to the alkali plating baths complexed by tartrates. However, it was found that brightening action was given by the complexing action of amines and sulfamic acid salts in the presence of a small amount of cyanides.
Bright thick platings were obtained by the addition of an adequate amount of these addition agents to each of the baths.