A pseudo-stable phase-splitting solvent composition that forms a single liquid phase when subjected to mild agitation and retains that single phase while the composition is applied to a surface, but which forms two or more laminar liquid phases promptly after being applied. A concentrated solvent film forms on the surface, under a film containing the other phase. The solvent preferably is denser than water, and the composition preferably is diluted with water. This enables the solvent to attack the surface at near full strength, and provides a water seal over the solvent film.The solvent composition can be used full strength or in diluted form for cleaning, reducing the microbial population of, or degreasing a variety of surfaces, and for stripping a variety of difficult-to-remove coatings from surfaces.