A short history of electroplating

The early history of electrodeposition of precious metals onto lesser metal can be reliably traced back to around 1800. Italian chemist and university professor Luigi Brugnatelli, is considered by many as the first person to utilize gold in the electroplating process. Brugnatelli was a friend of Allisandro Volta, who had just discovered the chemical principles that would later lead to the development of "voltaic"electrical batteries. Volta's first practical demonstration of this was called a "Voltaic Pile." As a result, Brugnatelli's early work using voltaic electricity enabled him to experiment with various metallic plating solutions. By 1805, he had refined his process enough to plate a fine layer of gold over large silver metals. In a letter to the Belgian Journal of Physics and Chemistry' later reprinted in Great Britain, Brugnatelli wrote: "I have lately gilt in a complete manner two large silver medals, by bringing them into communication by means of a steel wire, with a negative pole of a voltaic pile, and keeping them one after the other immersed in ammoniuret of gold newly made and well saturated".

Basics of electroplating principles

Electroplating can be defined as the deposit of a very thin layer of metal "electrolytically" to a base metal to enhance or change its appearance. Electroplating is done in a liquid solution called an electrolyte (fig. a ), also known as a "plating bath". The plating bath is a specially designed chemical bath that has the desired metal (i.e. silver, gold) dissolved as microscopic particles (positive charged ions) suspended in solution. The plating bath solution serves as a conductive medium and utilizes a low d.c. voltage (direct current). The object that is to be plated is submerged into the plating bath and a low voltage d.c. current is applied to the bath. Generally located at the center of the plating bath, the object that is to be plated acts as a negatively charged cathode (fig. b). The positively charged anodes (fig. c) that will complete the d.c. circuit are carefully positioned at the edges of the plating tank. A power source known as a rectifier (fig. d.) is used to convert a.c. power to a carefully regulated low voltage d.c. current.