Electroplating is not limited to metal surfaces. Plastic surfaces can also be covered with a thin layer of gold and other metals. Electroplating generally involves the deposition of metal ions from an electroplating solution onto an electrically charged surface. It requires a conductive substrate. Plastic is not conductive, which means that direct electroplating is not feasible. Electroplating on plastic must be performed in steps, with the plastic surface being modified to be made conductive.
(Freeimages / Eva-Maria Mikkola)
The first method of electroplating plastic is to roughen the plastic surface to allow the metal to adhere. The abrasive surface can then be electroplated to build up layers of metal. This process is referred to as electroless, autocatalytic or chemical plating. The second method is the application of conductive paint to the plastic before electroplating.
Electroless Plating
Start by cleaning the surface of the plastic so that it is free of grease, oil and other foreign elements. To be thorough, you could apply an extensive series of acids and bases. Then, rinse the surfaces with water to ensure that all cleaning agents are removed.
Drop the plastic to be electroplated in a chrome-sulfur bath. The acid will etch the surface to allow the metal to adhere. Another method is to sandblast the surface.
The plastic part should then be dropped into a bath of palladium chloride to allow the initial layer of metal to adhere. This will prepare the component for standard electroplating. The plastic component will then be electroplated with copper as another preparation layer before gold, chrome, nickel or any other metal is added as the final layer.
Paint Approach
To prepare a plastic surface for electroplating using paint, clean the surface the same way that you would for electroless plating. When clean, apply an inexpensive conductive paint. When the plastic is coated with conductive paint, you can begin the normal electroplating process.
Use caution when electroplating plastic to avoid exposure to toxic fumes.