There are different processes that can be used in zinc plating, and all offer advantages and benefits in specific types of applications. The most traditional of all of these are the cyanide processes, but they are no longer commonly used due to the highly toxic nature of cyanide and its risk to both people and the environment.
Some specific types of applications may still use the cyanide plating processes. There has been a concerted effort in the USA as well as in other countries to reduce the use of this chemical since about the mid-1970s.
Instead of the use of cyanide, most metal finishing companies have moved to the use of zinc acid or zinc alkaline plating. Both of these options provide suitable methods for different types of zinc plating requirements. Of the two, the zinc alkaline electroplating process is the most commonly used in most types of applications and provides a cost-effective solution without any loss of the characteristics of the traditional cyanide plating processes.
Throwing Power
With the correct setup of the factors in the zinc alkaline plating process, the throwing power of the zinc alkaline electroplating is superior to that of zinc acid. Throwing power is the ability of the solution to create an even, uniform, and consistent thickness over the entire part or component.
The measure of throwing power becomes a critical factor with complex parts and components. Poor throwing power means a wide variance in the thickness of the deposit, which has an impact on the final part.
Plating Method
Partly due to the superior throwing power of the zinc alkaline solution, it is typically recommended for rack plating. The zinc alkaline plating is also used for barrel plating as well, but the ability to provide an even, consistent layer over the exterior and interior surfaces of the part makes it the perfect match for rack plating.