When you talk about zinc chromate today, it refers to a protective coating. Zinc chromate plating is a finish that acts as a corrosive resistant coating to a base metal such as steel. It does not have a long history of usage, and what it has is, interestingly enough entwined with its color.
The Beginnings
Zinc chromate plating, sometimes mistakenly thought of as painting, has its origins in the 1920s. The Ford Motor Company is responsible for its origins. They applied it in car production. It became known as Ford Zinc Chromate. There was also
* DuPont Zinc Chromate
* Berry Brothers Zinc Chromate
Such terms referred to those who made the product but also the specific color employed. Each company opted for a singular color but no uniformity existed. In fact, no such standards existed until much later.
In the 1930s, the United State Military adopted the use of zinc chromate plating to act as an anti-corrosion barrier. They did not officially apply it as the norm until 1936. By the 1940s, it had become the standard. At this point, they began to establish consistency for the “color” of zinc chromate. They required reliability and uniformity in both performance and color. The standard color employed for American military aircraft became is now known as zinc chromate yellow.
The military also employed zinc chromate green. The black pigment created the green color that proved so successful in providing the aluminum wheel wells of military planes with additional protective measures. This time, the green zinc chromate plating made the airplane components more durable and provided them with increased resistance to UV light. They adopted this measure during and following the years of World War II, ending the application of this particular process in the early 1950s.
The Importance of Color
Color in zinc chromate plating is not simply a matter of fashion, style or preference. It actually indicates the level of protection the process confers as a finishing agent. While yellow remains a preferred color in several industries, it does not confer as much protection from corrosion as do the darker colors.
Zinc Chromate Plating Today
Today, zinc chromate yellow and zinc chromate green are still very much a part of several industrial applications. The automotive industry, which gave birth to the process, continues to be a main employer of zinc chromate yellow. It also remains in use for aircraft. Aircraft companies frequently employ it in covering aluminum alloy components. As a means of providing improved corrosion resistance, zinc chromate plating is a viable process that gets the job done and done so cost-effectively.
