Abstract: An aqueous metal cleaning composition is provided which comprises an alkalinity providing agent such as alkali metal carbonate and/or bicarbonate salts and a low foaming surfactant. The aqueous cleaning solution has specific foam height and foam collapse characteristics, and provides for substantially complete phase separation of a contaminant phase from the aqueous cleaning composition such that there is substantially no aqueous phase drag out into the contaminant phase; and the contaminant phase can be removed easily, and the aqueous cleaning solution can be recovered and reused.

Abstract: An alkaline aqueous cleaning composition for cleaning a substrate, e.g., a plastic or metal substrate, contaminated with industrial-type soil contaminants contains (i) an aqueous portion and (ii) an active-ingredient portion composed of (A) an alkalinity-providing agent and (B) a surfactant mixture containing (a) an active concentration of an N-octyl-2-pyrrolidone surfactant and (b) an active concentration of at least one aminocarboxylic acid surfactant such as N-coco-beta-aminopropionic acid. The active-concentration ratio of surfactant (a) to surfactant (b) is such as to provide the cleaning composition with the ability to remove a substantial portion of the contaminants from the substrate. At an active-concentration ratio of surfactant (a) to surfactant (b) of about 2.5:1, the surfactants have a synergistic effect on the industrial-soil-removing ability of the aqueous composition.