Brush-plating, the technique by which electrodeposits are made from electrolytes held in absorbent materials attached to portable electrodes, is now of some industrial importance. The necessity for properly designed equipment, including air and water cooling of the electrodes and safety devices in the power supply system, is definite. The properties of the solution are important and the required properties are only found in aqueous solutions of complexed organic salts of the metals concerned. The applications of the processes are wide and varied and are to be found in most engineering industries.