Where did the Brass Go?
Q. We have a potential customer who requires zinc diecasts to be plated with brass. We are new to the process of plating zinc diecasts. The few samples we have prepared so far look great after plating, but after top coating and baking, the brass seems to disappear. What are we doing wrong? M.K.
A. Brass is an alloy composed of zinc and copper. Upon baking, the copper component simply diffuses into the casting, resulting in “disappearing brass.” What you should do is put a thin copper deposit on the zinc diecast followed by a bright nickel layer. Then plate with brass. The bright nickel acts as a barrier layer preventing the migration of the copper and as a bonus will improve the appearance of the brass layer.
An alternative product for passivation...
Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.
White Bronze, Copper-Tin-Zinc Tri-metal: Expanding Applications and New Developments in a Changing Landscape
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