Surface treatments

ELECTROPLATING TREATMENTS (GALVANIC TREATMENTS)

1. General description

Electroplating treatments (galvanic treatments) consist of covering the surface of a metal (the substrate) with a thin layer of another metal by means of an electrolytic process. The substrate is immersed in a bath containing suspended molecules of the metal, intended to coat its surface. By passing an electric current between an immersed anode and the object to be treated (the cathode), which must be conductive, the suspended molecules deposit onto the surface of the substrate. Depending on the duration of the process and the intensity of the current, the thickness of the applied layer can be controlled.

This operation aims to protect the substrate against oxidation and to modify its color. The metals historically and mainly used in watchmaking are yellow Gold, Rose gold (pink gold), and rhodium (white Gold), all resistant to corrosion. Today, many other metals or combinations of metals expand the range of possible colors (such as ruthenium, black Gold, etc.).

2. History

It was the Italian physicist Luigi Galvani who discovered in 1780 that it was possible to protect a metal from corrosion by applying a thin layer of zinc to it. The various electrolytic techniques owe their name to him. The process found applications in goldsmithing, then in watchmaking from the mid-19th century onwards, and remains widely used today, although other technologies (CVD, PVD) began to develop toward the end of the 20th century. While gold and rhodium have historically been used in watchmaking and remain the most common treatments, other metals or metal combinations (such as ruthenium, black gold, etc.) have expanded the range of possible colors since the second half of the 20th century.

3. Advantages and disadvantages