Electroless plating is a method of depositing a transitional metal on to a metallic substrate using a process of chemical reduction. The actual deposit is usually in alloy form, for example, with electroless nickel an alloy of nickel phosphorous is deposited. The alloy content can be increased or decreased as required.

The advantage of this type of deposit is that in comparison to electroplated nickel the coating is far more uniform with hardly any variance in the distribution of thickness across the component.

Another advantage is that this deposit can be made even harder by using a subsequent heat-treat operation, for example the as-deposited hardness would typically be about 500Hv, whereas after heat treating this would increase to 1000Hv.

Typical examples of electroless plated components include valves, microwave guides etc.

Electroless finishes: