Techniques to improve the colour stability of some commercial stearic acid blends
Stearic acid used in pharmaceutical and cosmetic products must conform to the highest standard and meet stringent colour stability upon storage. Stearic acid blends are often necessary to obtain certain characteristics that cannot be met by pure stearic acid. The colour stability (colour after heating) of high purity stearic acid (>, 90%) is in the range of 0-2.5R with a mean of 1.1R, which is unacceptable to the pharmaceutical and cosmetic industries. Colour stable stearic acid blends can be obtained by treating commercial stearic acid blends with activated carbon and/or cellulose