Gold Plating Key Terms

Be conversant with the terminology for the gold plating process

By Howard Robertson

Gold plating (or gold coating) provides a goldlike appearance to industrial and nonindustrial products. In the jewelry industry, gold plating improves the look of different ornaments. In the manufacturing and semiconductor industry, gold plating enhances conductivity and hardness of the components’ surface.

Understanding gold plating key terms will help you make smarter choices. This guide covers some of the common terms that you will hear from gold plating vendors, including electroplating, karat system and KHN or Knoop Hardness Number.

Electroplating

Electroplating is an electrolytic method that deposits a very thin layer of metal on a metallic surface to enhance its appearance. Many gold plating service providers use this method to deposit gold on metal components.
Try: You can read through an explanation about the electroplating process at Finishing.com, an informative Web site for the finishing industry.

Karat

Karat is a unit that specifies the purity of gold. You must not confuse this with the unit 'carat' that indicates weight of a precious stone. If you want to buy pure gold, you will need to ask your vendor for 24 karat (or 24K) gold. 18K gold indicates that the product has 18 parts of gold and remaining six parts of other metal. You can understand this scale by reading through informative articles on reputable Web sites.
Try: Dickielee.com, an e-commerce business that offers handmade fashion jewelry, provides information on the karat system.

Microinches

Mostly, metal plating companies specify the thickness of metal coating in microinches. One microinch is one-millionth part of one inch and is equivalent to 0.254 micron.
Try: Metal Arts Specialties, a provider of custom gold plating services, offers a chart for conversion of different thickness units in the metal plating industry.

Knoop Hardness Number (KHN) or Knoop scale

For industrial products, the hardness of the gold plating is a very important parameter. You can specify the hardness of gold plating using a measurement system called the Knoop scale.
Try: Gordon England, a consultant, provides information on micro-hardness tests and a calculator for KHN. You can also read through an article on micro-hardness tests at CALCE Center for Advanced Life Cycle Engineering at the University of Maryland.

MIL spec plating

The U.S. Army Research Laboratory develops and publishes specifications for metal plating processes. You must check the specifications of the gold plating that your metal plating service provider follows.
Try: Nu-Metal Finishing, an ISO-certified surface finishing service provider, offers a summary of MIL specifications for gold plating services. Gold Plating Services is another metal plating service provider that publishes information on MIL spec plating.

Brush plating or selective plating

Brush plating or selective plating is one of the most popular gold plating methods. This method is specifically useful for on-site metal plating application requirements.
Try: Brush Plating Specialists, a brush plating service provider for the aerospace, electronics, petroleum and printing industries, publishes information on the basics of the brush plating method, its benefits and comparison with other plating methods.

Barrel plating

Barrel plating is an electroplating method suitable for plating small products in batches.
Try: To understand the basics of the barrel plating method, you can read through an informative article at Cooper Plating, a reputable metal plating service provider. Professional Plating is another plating service provider that offers information on the barrel plating process.