Abstract
Mechanism and detergency of foam washing and concerning basic investigations are reviewed. The foam was formed by injecting air into surfactant solution. When soiled substrate is placed parallel to the foam progress, Plateau border slides on surface of soiled substrate and remove the soil into the Plateau border. When porous substrate is fixed vertically to the foam progress, liquid and air in the foam is absorbed separately into the substrate, and foam is formed again from the porous substrate by the pressure of foam flow. Then the soil in the porous substrate is carried outward. Especially the vertical foam washing shows good detergency. The concerning basic investigations are dynamic action of single foam film, foaming action from porous media, and measurement of liquid volume fraction of foam by electric capacitance method.