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d. Soc. Cosmet. Chem. 26, 189-204 (1975) ¸ 1975 Society of Cosmetic Chemists of Great Britain Four methods for the characterization of dentifrices and other semisolids M. BLOCK* Presented on I2-I4th November 1973 at Nottingham at the Symposium on 'Evaluation of Product Performance' organized by the Society of Cosmetic Chemists of Great Britain. Synopsis--During the course of development work, the need arose for characterization and com- parison of batches of DENTIFRICES. Four methods used in other technologies are reported for their utility in the evaluation of these and other SEMISOLIDS. Force-time traces were recorded on a modified lnstron TENSIOMETER for a piston moving at constant speed down a full tube of toothpaste and again down the emptied one. The difference was the corrected initial FORCE for EXTRUSION. At the same time, a number of extruded drops were weighed. The mean weight of a drop was divided by the diameter of the orifice to obtain the TENSILE STRENGTH of the paste. A polyethylene disc resting on the surface of a jar of dentifrice was withdrawn at constant speed on an lnstron tensiometer. The force-time curve showed a characteristic maximum co- hesive force. The final value obtained on separation of paste and disc was a measure of STRINGINESS. A notched doctor blade was used to apply 10 parallel stripes of uniform width but increasing height upon a surface. Rotation through 90 ø permitted sag of the semisolid, giving a stripe number characteristic of RESISTANCE to SAG. INTRODUCTION Numerous semisolids are in household use to-day, ranging from medicinal ointments, skin creams and dentifrices in the bathroom, to sandwich spreads, mayonnaise, whipped cream and jellies in the kitchen, * Unilever Research Laboratory, 455 London, Isleworth, Middlesex. 189