The most common method of gold-plating jewelry today uses an electric current to attract positively charged gold particles in solution to a negatively charged substrate, the jewelry. The method, called electroplating, works with various metals including copper and nickel, which are often layered over a silver or iron base to prepare the base to receive the gold plating. A plating that is sufficiently deep and solid may then be engraved using a handheld engraving tool kit.
While gold will plate onto another metal readily, it does not always plate perfectly. Certain specific conditions must be met to create an even surface with good color and shine and without pitting, cracking or spalling (flaking). Manufacturers of electroplating solutions provide specially formulated organic additives to encourage just those conditions. In addition, these solutions require specific temperatures and electrical currents to ensure that the gold deposits at the advertised rate. If the electroplating process is too fast, the gold plating will appear porous or venous and the solution may begin to give off toxic fumes. If the electroplating process is too slow, the gold plate will be uneven and not as bright as desired.
Electroplating is as simple as a solution, a container and a battery. High school students perform basic electroplating experiments in a chemistry lab. However, just because it can be done does not mean it should be done. The science of electroplating metals, particularly gold, has been refined in order to create the most exacting conditions, allowing the circuit manufacturer and the hobbyist jeweler to obtain the same high quality results. If you intend to create gold-plated jewelry in a quantity sufficient to sell, investing in the appropriate equipment will ensure a superb product and repeat business.
The most common electroplating solution for gold-plating jewelry contains gold potassium cyanide salt. Cyanide is a powerful poison capable of being absorbed through the skin and causing death even in extremely small doses. When working with a cyanide salt, always wear protective clothing and eyewear. Keep potassium cyanide salt away from all acids. The combination will release hydrogen cyanide gas, which is odorless, colorless and deadly. Other electroplating solutions come in the form of acids that are also dangerous to handle. Read all Material Safety and Data Sheets (MSDS) that the manufacturer provides and follow all manufacturer’s instructions explicitly.
A Word on Nickel
It is a common practice to coat the base metal in a thin layer of nickel before adding the gold plating. Nickel provides a more stable base for the gold, giving the plating greater longevity than a silver-to-gold or copper-to-gold bond. Regardless of the strength of bonding, gold plating will wear away, particularly on rings and bracelets exposed to daily abuse. Many people have an allergy to nickel and develop contact dermatitis when exposed. Although the allergy may only manifest as a mild rash in the area of exposure, those with severe allergies may develop rashes in other areas, severe itching, blistering or dry patches resembling a burn. When distributing your gold-plated jewelry, notify your customers that the jewelry contains nickel to avoid causing unintentional harm.