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What is Involved in Chrome Plating Plastic?

Dale Marshall
Dale Marshall

Chrome plating plastic is a process that’s more complex than chrome plating metals, but it’s a viable process that produces a protective, bright, hard finish that’s aesthetically pleasing. A recent development in the plating industry involves spraying a conductive layer of a specially formulated silver or aluminum paint onto a plastic workpiece in a process called metalization. The silver paint is very costly, between $175 and $200 US Dollars (USD) for an 8-ounce (224-gram) container. The aluminum base paint is considerably less costly at between $75 and $100 USD for a 10-ounce (284-gram) container. Whichever metalizing method is used, the coating is sufficiently conductive in order to permit the workpiece to be treated like a regular metal workpiece in the chrome plating process.

Chrome plating evolved as a process of applying a very thin coat of chrome onto a metal surface, usually by immersing the object to be coated into a special bath that must be kept heated, agitated and charged with an electric current. The chrome is present in the bath as chromic acid, and when the electric current is passed through the bath to the workpiece, chrome migrates from the bath to the workpiece, bonding to it. Most objects that are chrome-plated are actually plated first with copper and then nickel before the chrome itself is plated. This process, also called electroplating, works because the metal workpiece conducts electricity. Until the metalizing process was developed, objects made of non-conductive materials like plastic and fiberglass generally cannot be electroplated. Chrome plating plastic using the metalizing approach generally requires that the metalized object be electroplated first with nickel and only then with chrome.

Chrome plating may be used on telescopes.
Chrome plating may be used on telescopes.

Another method of chrome plating plastic is called electroless plating. This system uses a chemical bath, like electroplating; unlike electroplating, however, it doesn’t use an electric current to deposit the chrome on the workpiece. In electroless plating, the chemical bath contains reducing agents that break down molecules of an alloy, which then re-forms on the workpiece. Electroless plating generally is used for nickel plating, following which a standard chrome plate can be applied to the plastic workpiece in a conventional electroplating bath.

Chrome plating plastic offers enhanced protection from corrosion and weather, and plastic or other non-conductive surfaces like fiberglass appear virtually identical to metal workpieces that have been electroplated with chrome. Reliable and cost-efficient methods for chrome plating plastic are significant advances for many industries, especially automotive and toy manufacturing. These systems are just as labor- and time-intensive, though — the plastic workpieces must be prepared every bit as thoroughly as their metal counterparts prior to plating. Poor preparation work and cutting corners in the process will result in poor-quality finished products.

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    • Chrome plating may be used on telescopes.
      By: dimedrol68
      Chrome plating may be used on telescopes.