Ross-Miles method

The Ross-Miles method is used for measuring the foamability of surfactant solutions and the stability of the foam produced, which is based on height measurement. It is named after the authors John Ross and Gilbert D. Miles. Several international standards were deviated from the method, of which ASTM D 1173 is the one closest to the original publication and most widely used.

Ross-Miles measurement setup

Background

Within the procedure suggested by Ross and Miles, the foam-forming solution is presented in a high, cylindrical tempered receiver vessel with standard dimensions. A second quantity of the same solution is introduced from above by means of a likewise standardized reservoir. This passes through the column and forms foam as a result of the turbulence on mixing with the receiving phase. The foam height is measured as soon as the reservoir is empty and also after one, three and five minutes.

The dimensions of the standardized receiver and reservoir lead to a height of the setup of more than one meter. The foam height measurement is taken at the top of the foam column only, not considering the changing height of the liquid-foam-boundary due to drainage. However, additional information about drainage can be obtained by measuring both the upper and lower foam boundary.

Bibliography

ASTM D1173 − 07 (Reapproved 2015): Standard Test Method for Foaming Properties of Surface-Active Agents.
J. Ross, G. D. Miles: An Apparatus for Comparison of Foaming Properties of Soaps and Detergents, Oil & Soap, May 1941, P. 99-102.