Electro-chemical tank operations apply electric current through a conductive part submerged in a tank containing an electrolytic solution. Most of these operations are electroplating (metal ions in solutions are deposited on to the conductive part). However, there are some operations where the metal from the conductive part is transferred into the solution. Typically, when current passes through the metal part, gas bubbles (usually hydrogen gas) form in the tank solution. These bubbles burst and produce a mist of the tank solution. Foam additives or surface tension adjusters may be added in the tank solution to reduce the emissions. Wet scrubbers, mist eliminators, and HEPA filters may also be used to control emissions. Typical electro-chemical tank operations include decorative chrome plating, hard chrome plating, chromic acid anodizing, nickel plating, copper plating and cadmium plating.