Silver plating is a process that can impart a very thin coating of silver to another metal for either decorative or utilitarian purposes. The earliest form of silver plating involved using heat to fuse silver and copper, though most modern examples use an electroplating process. Modern electroplating processes typically involves ions of silver held in a solution that are deposited onto a conductive material, such as copper, by flowing electricity. This may be used to create decorative pieces that are less expensive than pure silver, or to improve the conductivity in electronic components.
Some of the first silver plating was developed in the 1740s. The process was discovered during repair work, when silver was accidentally melted onto a copper object. Later experimentation showed that silver could be applied to copper in this method and then used to create a variety of objects such as flatware, buttons, and candlesticks. It was possible to apply the silver in a very thin layer, allowing the products to be sold for much less than solid silver versions. This method was largely replaced by electroplating, though it may still be useful in certain circumstances.
Electroplating was discovered in the first part of the 19th century, and has been used to coat many different metals onto conductive materials. This process may be used for decorative purposes just like older plating methods, though it typically produces a brighter product with more luster. Older methods generally used sterling silver, while electroplating can coat a material with pure silver atoms. The coating deposited by electroplating also tends to be substantially thinner that older methods produced.
Another important modern use for silver plating is in electronics. Silver plating may be used in applications such as electrical connectors or capacitor plates. Gold tends to be a more effective conductor than silver and does not oxidize, though silver is often preferred since it is less expensive. Oxidation tends to have little or no adverse effects on capacitor plates, so the comparatively less expensive silver plating may offer even greater benefits in those applications.
A third way silver can be plated onto a surface is through the use of Tollen's reagent. This test typically involves mixing silver nitrate and ammonia in a test tube that is suspended in warm water. The compound being tested is then introduced and if a positive result is obtained, the silver will separate from the solution. This may result in the testing apparatus becoming plated in a layer of silver.