Most of the cold wave kits now on the market for home waving contain the equivalent of 6% thioglycolic acid, although a few contain as little as 4.6%, and one contains as much as 7%. All are at a pH of about 9.3. Beauty shop waving lotions for bleached and dyed hair usually contain the equivalent of 4.6% thioglycolic acid, while lotions for waving regular or normal hair contain the equivalent of anywhere from 6.5% to 8.3%, depending on the method of use and how fast they are designed to work. Generally, lotions containing the higher concentrations of thioglycolic acid are used on resistant or hard-to-wave hair. the pH is usually between 9.2 and 9.3 for all types of lotions. Ammonia is used as the alkali to adjust the pH of the thioglycolic acid to 9.2-9.3 inn most of the various brands. Monoethanolamine (MEA), a non-volatile alkali, is used instead of ammonia in some lotions too adjust the pH. MEA is used both by itself and in combination with ammonia. usually, in the latter case, the MEA is used to
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