Plating is the process of overlaying a thin layer of a metal like gold, silver or rhodium over a base metal. Almost any item can be plated, and is very common in fine jewelry since plating is a great way to improve the appearance of jewelry. It also adds a layer of protection to a piece, as the outer layer of metal enhances scratch and corrosion resistance. Here at ShineOn, we offer several variations of plated jewelry, including most of our gold and rose gold pieces. The process of plating is fascinating, and our jewelers meticulously follow these steps almost every day. Read on to see how we make our plated pieces sparkle!
The most common method of plating jewelry is called electroplating. In this method, an electric current is run through a liquid solution containing dissolved metal salts. The piece to be plated is submerged in the solution, and the electric current causes the metal salts to attract and plate onto the piece. However, the most important stage of plating takes place before the jewelry is submerged.
Preppin’ Ain’t Easy
The process of preparing jewelry to be plated is an integral part of the quality of the plating and the maintenance of the electroplating machinery. The jewelry must be completely clean, free of any oils, and as smooth as possible. The first step is to polish the item with a polishing wheel, which uses high power buffing and polishes to smooth away any small scratches or pitting.
The piece is then placed in the ultrasonic cleaning machine. These machines use powerful ultrasonic waves (far beyond the level of audible sound) in a tank filled with cleaning solution, which creates millions of tiny bubbles. These bubbles penetrate every small line, crevice and corner and dislodge any contaminants or dirt within them.
The next step is to steam clean the piece. A high powered jet of hot steam blasts the jewelry and removes any last bit of grime left on the surface. Now that the jewelry is shiny, clean, and polished, it’s ready for plating!
Plate Like You Mean It
The process of plating varies slightly depending on the metal being plated and the base metal being plated over. Depending on the base metal, sometimes a thin layer of metal, called a strike or flash layer, is first plated on to improve the bond between the piece and the plating metal. This flash layer also prevents soluble base metals from contaminating the plating tanks. If the base metal is a reactive metal, like copper, the flash layer can also help extend the life of the plating by providing a barrier between the core and outside elements.
Once the flash is in place, or if the flash is not necessary, the piece is often plated with an additional base metal. This can be a plating of nickel, copper or palladium, and serves to extend the longevity of the plating.
Finally, it’s time for the jewelry to be plated in the chosen metal. The piece is attached to a negatively charged cathode and dipped into the bath of solvent and dissolved metal. The metal ions in the solution are positively charged, and are attracted to the negative anions causing them to “plate out” onto the surface of the jewelry. Every metal has it’s own plating bath, as well as a specific electric current voltage and temperature.
The amount of time in the plating bath determines the thickness of the final plating. Plating is measured in micrometers (µm), and generally ranges from .25 – 2.0 µm. As a reference, the thickness of a human hair is 100 micrometers. The recommended plating thickness varies based on the levels of use the piece will typically be subjected to; High use jewelry like rings and watches requires a thicker of plating, at least .75µm, if not more. Lesser use jewelry like earrings only need a thin plating to achieve the same look and not worry about durability. At ShineOn, we consistently use a plating of just under 1µm, which provides a more durable finish to all of our jewelry.
While plating provides a barrier to tarnish and wear, it is not permanent. A well plated piece that is carefully treated and protected by its wearer can last years without the base metal showing through. However, if the piece is not treated well, exposed to abrasive chemicals, or worn daily, the plating will begin to wear off, exposing the base metal underneath. Thankfully, most jewelers will be able to have your piece replated without breaking the bank.
Obviously, not all jewelry needs to be plated; Plating is just one out of the numerous methods of making high end jewelry into the best possible end product.