Electroplating plastic is possible but not straightforward because electroplating requires a conductive surface, and plastic is naturally non-conductive. To plate plastic, the surface must be made conductive before the metal deposition can occur. There are two main methods of achieving this.
The Electroless Plating Method
This involves roughening the plastic surface to create better adhesion for the metal. The plastic is cleaned to remove contaminants, then etched with a chrome-sulphuric acid bath or sandblasted to pit the surface. Next, the plastic is treated with palladium chloride to deposit a catalytic metal layer. Following this, a layer of copper is added through electroless plating, creating a conductive surface on which traditional processes such as gold, chrome or zinc nickel plating can be carried out.
The Paint Method
Conductive paint is applied directly to the cleaned plastic surface. After the paint dries, the piece is electroplated, first with a copper layer and then with the desired metal.
These processes require several steps and chemical treatments to ensure metal adheres properly to the plastic substrate. For chrome finishes, vacuum metalising may be a better alternative for certain uses due to durability concerns. The work is highly specialised and can only be effectively performed by experienced companies such as https://www.swmf.co.uk/surface-coatings/zinc-nickel-alloy-plating.
“Standards and Guidelines for Electroplated Plastics”, published by the American Society of Electroplated Plastics in 1984, remains the authoritative reference book on best practices and technical standards for electroplating on plastic substrates.
While plastic cannot be electroplated directly, careful surface preparation, including conductive coating with chemicals or paint, enables effective electroplating on plastic parts.