The production of clean glass surfaces for vacuum evaporation purposes has been studied using a number of different chemical cleaning techniques. The principal cleaning methods investigated were vapour degreasing, using a range of solvents, and high- and low-frequency ultrasonic agitation of an isopropyl alcohol bath. The cleanliness of glass surfaces after treatment was assessed from their coefficient of friction, wetting properties and adherence to vacuum deposited coatings. In terms of these properties vapour degreasing in pure isopropyl alcohol produced the cleanest surface. However, low-frequency ultrasonic agitation was the most effective method of removing gross surface contaminants. The cleaning of intricately shaped components is briefly discussed and it is shown that the gas pressure above the cleaning medium must be initially reduced to allow the solvent to enter cavities and thus provide maximum irradiation of the surface. Ultrasonic cleaning was found to be most effective when operated at low frequency (25 kc/s) with an undegassed fluid under atmospheric pressure.