Miscellaneous metal plating techniques

BARREL PLATING:
The method was used to impart metallic finish to small parts before the electroplating method was developed. The method is still used.
Process:
A conductive coat of silver is precipitated on the plastic part from silver nitrate solution to make the m conductive. The n the part is plated in the rotating plating barrels containing acid copper plating solution and copper anodes. After the copper is deposited the articles are polished with a steel shot in a burnishing barrel. A plating of gold, silver or nickel is deposited on them by another barrel plating operation.
HOT STAMPING:
The conventional hot stamping process can be used to put a gold, silver or other metallic decoration on plastics. Now high lustre metalized silver foils or roll leaf are developed for exterior use.
SPRAY PLATING:
Here silver or copper plating is deposited by chemical reaction of water based solution on the substrate. The base coat and a top coat are usually incorporated.
Here the silver containing salts are deposited on the product through a dual nozzle gun. When copper is to be applied the silver is applied first and then the copper is applied on the silver coat. A typical system will consist of a spray booth with special bottom to recover silver, mixing vessels, demineraliser for water purification and four guns: one for water to clean the part after each processing step, one for the activator to treat surface of the part, a dual nozzle gun for silver and a dual nozzle gun for copper.