Anodising and Phosphating Metal Finishing Electroplating involves the deposition of a thin protective layer (usually metallic) onto a prepared surface of metal, using electrochemical processes. The process involves pretreatment (cleaning, degreasing, and other preparation steps), plating, rinsing, passivating, and drying. The cleaning and pretreatment stages involve a variety of solvents (often chlorinated hydrocarbons, whose use is discouraged) and surface stripping agents including caustic soda and a range of strong acids, depending on the metal surface to be plated. The use of halogenated hydrocarbons for degreasing is not necessary as water based systems are available. In the plating process, the object to be plated is usually used as the cathode in an electrolytic bath. There are three main types of plating solutions: are acid, or alkaline solutions and may contain complexing agents such as cyanides.
surface plated) but usually high in heavy metals (including cadmium, chrome, lead, copper, zinc, and nickel), cyanides, fluorides, and oil and grease, all of which are process dependent. Air emissions may contain toxic organics (such as trichloroethylene and trichloroethane). Cleaning or changing of process tanks etc.