ISO 304:1985

Surface active agents — Determination of surface tension by drawing up liquid films

The maximum force is measured which is necessary to act vertically on a stirrup or a ring, in contact with the surface of the liquid being examined placed in a measuring cup, in order to separate it from this surface, or on a plate with an edge in contact with the surface, in order to draw up the film that has formed. The surface tension of pure liquids or other solutions can also be measured by this method.