PURPOSE: To improve the safety of a combustible solvent against ignition during storage, transportation, etc., by adding water containing a surfactant to the solvent to form a noncombustible or difficultly combustible mixture and to regenerate only a necessary amount of the solvent in a pure state from the mixture by distillation.

CONSTITUTION: Water and a surfactant are added to a hydrocarbon solvent, a silicone solvent or a terpene solvent used for a vapor cleaning work to form a noncombustible or difficultly combustible storable solvent. When the combustible solvent is needed, only a necessary amount of the storable solvent is distilled to regenerate the combustible solvent therefrom.