* When used at 10% in finished formulations, the level of Salicylic Acid
is 2% and Alpha Hydroxylauric Acid is 1%.
* The greatest efficacy seems to be at pH 2.5 - 5.0. A rule of thumb is
the lower the pH, the greater the efficacy.
* The free acid form of these hydroxy acids gives maximum efficacy. Care
should be taken not to add reactive basic ingredients that would convert
these acids to their less effective salt forms.
* Non-ionic emulsifying systems work the best in keeping both acids stable.
excipients which may be potentially irritating since a penetration enhancer
is contained in this hydroxy acid complex.
WP Smith, Hydroxy Acids and Skin Aging, Soap Cosmetics Chemical Specialties,
69(9) 54-58, (1993)