Abstract: Process and apparatus for treating a porous, absorbent material with a foamable chemical composition, in which a liquid chemical composition that is capable of being foamed, or a porous, absorbent material substrate containing such liquid composition, comes in contact with a porous substance through which air or other inert gas is being forced, to produce an aqueous foam which is used to treat the substrate. The invention eliminates the need for expensive foam generating and applying equipment, and makes it possible for presently employed fabric processing equipment to be inexpensively modified to use aqueous foam treatment for dyeing or other applications.