A brass plated key.
Brassing is the process of depositing a thin layer of brass on the surface of a metal object. This process takes place in a chemical bath that is charged with electricity. The thickness and quality of the brass lining is determined by the time in the bath, the chemicals used, and the configuration of the tank.
The process that applies a brass plating to an object is known as electroplating. In this process, the substrate (the metal object or surface to which the brass will be applied) and a brass source are immersed in a chemical bath. Electricity enters the system through the brass and exits through the substrate. It transports brass particles through the solution, towards the substrate. As soon as these particles reach the substrate, they adhere to the surface and bind to it.
The composition of the chemical bath in which the brass is immersed is significant. Brass is almost always made in a cyanide solution. While other chemicals can be used, most companies continue to use cyanide because it reacts well with brass.
The substrate material and brass are held in the plating tank while the brass plate grows. It can take anywhere from a few hours to a few days or weeks to create a layer of brass on a substrate. The time the process takes depends on the desired thickness of the final product.
The temperature of the chemical bath also influences the time it takes for the brass to grow. The ideal temperature range is between 95 and 105 degrees Fahrenheit (35 and 40.5 degrees Celsius). A plaque grown at 75 degrees Fahrenheit (24 degrees Celsius) will take about twice as long to grow as a plaque grown within the ideal temperature range.
There are different types of containers that can be used for brazing, the most common being barrels and tanks. Barrel plating is useful for small objects that must fall freely. The cylinder rotates throughout the process, creating a uniform brass surface on all sides of the substrate. Tank plating is most often used with large sheet metal. In tank plating, the substrate is lowered into the tank where the coating is deposited evenly on the flat surface of the substrate.