By electroplating silver, it is possible to eliminate the tarnishing problem created when chemists add other metals to pure silver to increase the durability of the sterling silver item. In order for the item to be protected from tarnish, the chemist will carry out a procedure called electroplating. Here is how it is carried out.
Why not simply put the silver item to use without electroplating the silver in the first place if the other metals create the problem? Silver that has been refined to 99.99% will retain the warm, silvery luster and will not tarnish. The problem is that it is one of the softest of the precious metals and will easily wear. To eliminate the problem, some hardening metals must be added during the smelting process.
Tarnish is caused by a thin layer of corrosion that can occur over copper, silver, brass, magnesium and aluminum as well as many other metals due to a chemical reaction. Silver needs hydrogen sulfide to create tarnish.
Frequently, electroplating sterling silver with a thin layer of rhodium is done to allow a piece of jewelry to remain tarnish free.
Before the plating can begin, the part to be plated must be thoroughly cleaned.
The part to be plated is called the cathode of the circuit. The second part of the circuit is the anode which consists of a pure piece of rhodium. The anode and cathode are placed into the electrolyte into which some metal salts have been added. A battery power supply is set up and the anode is connected to the positive side of the battery and the cathode is attached to the negative side. Both leads are immersed into the electrolyte. Once the power is flowing, the rhodium will begin to flow across to the silver. In a short time, the task is complete.
Rhodium is one of the platinum family of metals and gives a bright and shiny surface to the plated object. It is one of the hardest metals known to man. It is also the highest priced metals. Eighty percent of the world’s production is used to make automobile catalytic heaters. It is highly non-corrosive. In some cases, it is applied to white gold jewelry to make the metal even brighter.