There are many types of coating solutions that are used in both brush and tank coating. The solution used is determined by the base metal of the workpiece to be plated, the purpose of the plating, and the desired metal finish on the finished workpiece.

There are many different chemicals that are used in solutions made for specific coating purposes. Often there is more than one way to plate the workpiece. In some applications, a single solution is sufficient, but in other cases, more than one solution is required. The use of two tanks is sometimes referred to as duplex coating. A duplex coating is a two-layer deposit with each layer achieving a different purpose.

An example is the use of gold and nickel plating solutions on copper jewelry. The nickel prevents the gold from dispersing into the copper and causing the gold to tarnish. Gold is the final layer to provide the fine finish desired on most jewelry. In applications where corrosion resistance is important, the copper plating solution seals the surface, while the nickel provides corrosion resistance. In the salvage of worn parts that require thick deposits, copper is an inexpensive and easily applied deposit that achieves the majority of buildup, while nickel provides a hard, wear-resistant, and/or corrosion-resistant topcoat. .

In most cases, a pre-plate deposit is required before the final step of applying coating solutions in what is called a build-up coating deposit. A thorough water rinse is used after completing the plate preparation step. The pre-plate is used to obtain maximum adhesion of the build-up deposit to the base metal. When used, it is actually the preplate that provides the molecular adhesion between the base metal and the investment deposits. The proper pre-plate, if required, is determined by both the base material and the final coating solution. In a few cases, more than one pre-plate solution is required. Both nickel and copper can be pre-plaque solutions.

The electroplating process occurs when metal in ionic form is moved from a positive to a negative electrode. An electrical current passed through the plating solutions being used causes the workpiece to become coated with the metal in the solution. Electroplating is done for many reasons, usually to beautify, insulate, or protect an object. It can also be used to increase the corrosion resistance, conductivity and weldability of metal objects. Plating protects in one of two ways, either sacrificially or mechanically. Zinc and cadmium protect the base metals they sacrificially coat.

They are more reactive to corrosion than iron or copper alloys, so they corrode first, before the base metals. Copper, nickel, chromium, and most other metals commonly used in plating solutions mechanically protect the base metals. They protect the base metals by forming a protective layer; therefore protection is good only as long as that coating is intact.

If there is a defect or break in the protective layer, the base metal will corrode before the coating. The most common metals used in plating are copper, nickel, gold, silver, chrome, zinc, and tin. Copper is the most common of all metals to be coated with another metal. Its finish is smooth, ductile, and easy to weld, but it is rarely used as an end plate because it tarnishes easily.