LABORATORY MODELS FOR DEPILATORY PERFORMANCE 371 Cetyl alcohol 6.00 • w/w Lanbritol Wax 10.00 •o w/w Thio-compound 5.00 •o w/w Neutralizing base q.s. Water to 100 In most cases this formula gave a satisfactory cream, but even where separation of the product took place, for the purposes of the test it was not considered that this had any significance. All determinations were carried out in duplicate at room temperature at 25øC. The depilation times shown below are the mean of two readings. RESULTS Type of thio compound and neutralizing base Thioglycerol. •o w/w Neutralizing base of commercial pH Depilation time material (min) Lithium hydroxide 2.0 11.6 6.0 Sodium hydroxide 1.9 11.2 4.5 Potassium hydroxide 2.6 11.5 6.5 Calcium hydroxide 1.7 11.9 6.0 Strontium hydroxide 6.2 11.0 8.0 Barium hydroxide 7.3 11.0 8.0 Thioglycollic acid. •o w/w Neutralizing base of commercial pH Depilation time material (min) Lithium hydroxide 4.6 11.8 5.0 Sodium hydroxide 4.5 11.4 5.5 Potassium hydroxide 6.1 11.7 7.0 Calcium hydroxide 4.0 12.1 7.0 Strontium hydroxide 14.5 12.0 7.5 Barium hydroxide 17.2 12.0 13.0

372 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ThiomMic acid. Neutralizing base % w/w of commercial material pH Depilation time (rain) Lithium hydroxide Barium hydroxide 4.2 15.8 11.6 12.1 15.0 15.0 2-mercaptopropionic acid. Neutralizing base % w/w of commercial material pH Depilation time (min) Lithium hydroxide Sodium hydroxide Potassium hydroxide Calcium hydroxide Strontium hydroxide Barium hydroxide 4.0 3.9 5.3 3.5 12.5 14.9 11.8 11.3 11.4 12.2 11.0 11.2 8.0 7.5 14.0 13.5 13.0 10.0 3-mercaptopropionic acid. Neutralizing base •o w/w of commercial material pH Depilation time (min) Lithium hydroxide Sodium hydroxide Potassium hydroxide Calcium hydroxide Strontium hydroxide Barium hydroxide 4.0 3.9 5.3 3.5 12.5 14.9 11.5 11.9 11.5 11.3 12.7 12.7 6.0 7.0 8.0 14.0 6.5 6.5 rhiodiglycol. Neutralizing base % w/w of commercial material pH Depilation time (min) Lithium hydroxide Sodium hydroxide Potassium hydroxide Calcium hydroxide Strontium hydroxide Barium hydroxide 3'1 2.9 3.6 2.7 9.7 11.5 11.5 11.0 12.2 12.2 12.6 12.2 15.0 15.0 12.5 15.0 15.0 15.5