448 - UI � - UI � � 100 8 6 4 2 10 4 1 JOURNAL OF COSMETIC SCIENCE I I I I I I ! l I I I I --------------..I------- -- - - • - -_-._-•-----.L-----.J----.J-- • • • -- • --- ----'- • -• --• -- -----• • ------ J I j I I I Facial Mask I I I I I I I l I I I I I I I I I I --------------1--------------r------r·----1--·-1---------------r-------------- ------- • T = 5 °C --------------1---------------j--------:-----1----1---------------j-------------- ------- * T = 10 °C - T = 15 °C ' I , , , , , 6 ············i···· 1[ ········i ·····[····[ ··· ·· · l · ·········· "----'--___ $ T 2_ ____,, 0 c - : : t : : : :::: :::T::::::::::J .:L:i:f.. ::::::::r·,·:::: :: ::L::I: T::: :::::: : : : : : : $ ! : : : : : : : : : ffi : : : i i i : i i w i �: i I i 11 I Ir$ 4 6 8 10 2 y (1/s) 4 6 8 100 Figure 4. Effect of temperature on the apparent viscosity of the facial mask (5 ° -20°C). 100 8 6 4 2 10 4 2 1 1 t I I I I I 1 I I I I I I 1 --------------..1•---•----•-----L--------L-----.I-••• .J •• _____________ ._ ___ ___________ ,L ____ _ I I I J J I j Facial Mask I I I I I I I I I t ! I I I I I I I J I I --------------..1---------------l..--------1------.J----..1---------------1---------------"------ $ _____________ /� _________ j _____ _j ___ J ___ ___ _________ _j ___________ )_____ ■ T = 25 °C -- T = 20 °C :� 0: : : : : : � T =30 °C --------------il---------0�-------6----(---(--------------�--------------i----- _____ o __ T=4_o _ _ 0 ___ c -- ! !) � : 6 : : ' ' ■ ' ' ' ' ' ' ::: ::::::: __ --r::::::::::::: :� ::: :: :: �-::: :: :� :: : ::: :: :: : ::� ::::::: ::::::::' :::::::: :: :::r::r::::::: _: :::: , , , , ' CD , , , , J· ·· 1 +:. · ff/�+ +r -------------+-----------+-----+---+--+----------------------------+------+---t------------------::······r : / : j j : / j : : � 4 6 8 10 2 y (1/s) 4 6 8 100 Figure 5. Effect of temperature on the apparent viscosity of the facial mask (20°-40°C).

l. - s::- 100 8 6 4 2 10 4 2 1 FACIAL MASK OF DEAD SEA MUD 4 6 8 10 y (1/s) 4 6 8 100 Figure 6. Effect of temperature on the apparent viscosity of the facial mask (40°-60°C). 449 here that this type of starch was modified to start gelatinization at a low temperature, compared to natural starches. For example, the initial gelatinization temperature of wheat starch in water was found to be in the range of 5 5 ° to 66°C and for corn starch in water was found to be in the range of 65 ° to 76°C (17). This gives an advantage for the suspensions utilizing this polysaccharide: the system will be highly stable at room temperature. As the rheological parameters are concerned, the results of Table I demonstrate that the facial mask mud yield stress is strongly dependent on temperature. The values of the yield stress reflect the behavior of the apparent viscosity with temperature. The three stages of temperature effect on the yield stress can be distinguished easily in Table I. On the other hand, the shear-thinning behavior, which can be assessed by inspecting the values of the flow index, n, is the most pronounced at the end of the second stage and at the beginning of third stage (40 ° -45 ° C). SHEARING TIME EFFECT As mentioned above, the apparent viscosity of the facial mask was measured by increas­ ing (forward measurement) and decreasing (backward measurement) the shear rate in order to test the presence of a time-dependent behavior. The flow curves (T versus �) of the mud mask at different temperatures are shown in Figure 7. There are hysteresis loops between the forward and backward curves, indicating a time-dependent rheological