There are about 700 commercially available surface-active agents and it takes experience to select the proper anionic, nonionic, cathionic, or amphoteric detergent for specific metal cleaning compounds. The anionics are widely used in electrocleaning compounds. The nonionics or combinations of the nonionics with anionics have been useful in soak and spray cleaners. Some nonionics have defoaming properties so it is possible to control the amount of foam by properly selecting and compounding nonionic and anionic surface active agents. The cationics and amphoterics are useful for leaving a film on the metal surface to prevent rusting or oxidation.
An almost universal requirement today is that surface active agents be biodegradable. This means they are destroying by the bacteria in the sewage and waste treatment processes.
The most widely used surface-active agents in metal cleaning are the sodium linear alkylate surfonates and the fatty alcohol sufates in electrocleaning compounds, the sodium linear alkylate sulfonates and the oxythtylated alcohol type of nonionics in soak cleaners, and the low foaming ninionics in spray cleaners. A complete list of all the available surfactants is published annually.
A special application of surfactants is the development of water base combinations of soaps and surfactants for the removal of Tripoli buffing compounds from polished zinc die castings and other buffed metal surfaces. These products are normally used at 30 to 60 g/l in water for hot soak cleaning or ultrasonic cleaning to remove impacted buffing compounds.
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