Electroplating is the process of coating one metal or metal object with a very thin layer of another metal, typically by applying a direct electric current. This partially dissolves the metals and creates a chemical bond between them. The coating applied by electroplating is usually around 0.0002 inches thick.
There are various types of plating used to create jewelry – from different karats of yellow gold to 18k rose gold, black and white rhodium, palladium, silver and anti-tarnish.
Electroplating on jewelry is done for a number of reasons. Some forms of electroplating are both protective and decorative; metals such as gold and silver are plated to create attractive finishes as well as for affordability and durability.
By creating a chemical bond, the plating is a permanent addition to the surface of the base metal. This means that it will not naturally fall off or separate. However, plating can be worn off over months and years of use and wear.
Because this top layer is so thin, it has very specific uses. Some metals are used as a coating, because they give added protection from rust, damage or corrosion.
Plating is It is usually applied to jewelry to add visual appeal as well as added protection and durability.
The electroplating process involves passing an electric current through a conductive solution called an electrolyte. The metal atoms that plate an object come from the electrolyte, so if you want to gold-plate a jewelry item, the electrolyte must be made from a solution of a gold salt.
Two terminals called electrodes then are dipped into the electrolyte and connected to a circuit with a power supply. When electricity flows through the circuit, the electrolyte splits up and some of the metal atoms it contains are deposited in a thin layer on top of one of the electrodes to become electroplated.
The longer the process continues, the greater the thickness of the coating. As the electroplating process continues it uses up the metal salts.
Gold plating can be added to almost any metal, including brass, copper or nickel. Silver items can also be gold-plated.
Some pieces will actually be plated with a wide range of metals even if you can only see the gold plating. If you have a silver component, for example, it will first be plated with copper because copper will make the plating tarnish slower. Then a plate of nickel will be added to improve the bond and strengthen the barrier.
This means that component will actually be a composition of silver, copper and nickel substrate layers with a final gold layer added on top.
Some newer methods involve using titanium nitride down as a rough layer, and then gold is electro-deposited into the roughness of this layer. This method gives a very full gold color but adds extra protection and a much longer lifespan to the gold plating.
If your finish starts to tanish or chip over time, it can be re-plated to return to its original luster. A gold plating service can re-plate and restore a gold finish and prevent anyone from seeing the other metal that sits below the surface.
For the metals commonly covered by a plating of gold, their atoms diffuse into the gold layer itself. This diffusion happens over time and is what causes a gradual dulling of the gold color. The surface will eventually tarnish, often over the course of years.
Re-plating safely returns your gold color.
Gold plating eventually wears off, but the rate of tarnish can vary greatly depending on the piece.
There are three main factors that determine how quickly your gold plating will go:
- Thicker plating lasts longer because there is more to wear away.
- Gold has an affinity for some metals. Gold holds tighter to silver and titanium than it does to copper or nickel, and the tighter this hold, the longer the plating will last.
- The more an object is rubbed or used, the faster its plate will wear away.