Cleaning metal components after the Montreal Protocol : Introductory review

Until recently, the manufacturing and finishing industries have placed heavy reliance on the use of pure methyl chloroform or chlorofluorocarbon solvents to achieve acceptable levels of cleaning or precleaning of metal components. Much effort has been devoted since the signing of the Montreal Protocol to finding replacement cleaning agents for these and other banned or controlled substances and it is now clear that a variety of different cleaning processes must be developed. In the long term it is likely that the vast majority of industrial cleaning will be carried out in aqueous solutions making it necessary to investigate the special problems involved in cleaning difficult components. A review, which summarises the issues and current problems being encountered in the search for replacement cleaning processes, is presented. Also considered are the relevant techniques and experimental procedures which can be used to investigate surface cleanliness and related phenomena.