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].Cosmet. Sci., 58, 45-51 CTanuary/February 2007)
Clay facial masks: Physicochemical stability at different
storage temperatures
VIVIAN ZAGUE, DIEGO de ALMEIDA SILVA,
ANDRE ROLIM BABY, TELMA MARY KANEKO, and
MARIA VALERIA ROBLES VELASCO, Department of Pharmacy,
School of Pharmaceutical Sciences, University of Sao Paulo, 580 Prof
Lineu Prestes Av., Bl-13, 05508-900, Cidade Universitciria,
Sao Paulo, SP, Brazil
Accepted for publication September 20, 2006.
Synopsis
Clay facial masks-formulations that contain a high percentage of solids dispersed in a liquid vehicle-have
become of special interest due to specific properties presented by clays, such as particle size, cooling index,
high adsorption capacity, and plasticity. Although most of the physicochemical properties of clay dispersions
have been studied, specific aspects concerning the physicochemical stability of clay mask products remain
unclear. This work aimed at investigating the accelerated physicochemical stability of clay mask formula-
tions stored at different temperatures. Formulations were subjected to centrifuge testing and to thermal
treatment for 15 days, during which temperature was varied from -5.0 ° to 4 5 .0 ° C. The apparent viscosity
and visual aspect (homogeneity) of all formulations were affected by temperature variation, whereas color,
odor, and pH value remained unaltered. These results, besides the estimation of physicochemical stability
under aging, can be useful in determining the best storage conditions for clay-based formulations.
INTRODUCTION
Face mask beauty treatments are among the oldest cosmetic preparations. Current
interest in the development of these formulations is attributed to their warmth, tight-
ening, and cleansing effects. Characteristics such as ease of application and removal,
reduced time for drying and hardening, and dermatological innocuousness are also
required (1-3). One of the most popular face masks is the wash-off type based on clay
raw materials, also known as clay facial masks or the once-fashionable "mud packs" (1).
Cosmetic science and aesthetic medicine have been rekindling interest in clay facial
masks mainly due to clay properties such as particle size, cooling index, high adsorption/
absorption capacity, and plasticity (4-6). Clay facial masks are composed of a high
percentage of solid particles (over 25%) dispersed in a liquid vehicle. The concentration
Address all correspondence to Vivian Zague.
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