PEARLESCENT STRUCTURES 579 Table I Pearlescent Properties of Aqueous Polyoxyethylene Fatty Ether/Fatty Alcohol Concentrates Polyoxyethylene Fatty Ether Solubility • Composition a HLB in Water None Pearlescence Rating Fatty Alcohol Lauryl Myristyl Cetyl Stearyl POE (4) lauryl ether POE (23) lauryl ether POE (2) cetyl ether POE (10) cetyl ether POE (20) cetyl ether POE (2) stearyl ether POE (10) stearyl ether POE (20) stearyl ether POE (2) oleyl ether POE (10) oleyl ether POE (20) oleyl ether 97 169 53 129 157 49 124 15.3 4.9 12.4 15.3 D S I D S I D D I I s ß o . 1 2 2 3 3 3 2 3 2 3 2 o.. 3 3 2 2 2 1 3 3 2 a Brij surfactants, Atlas Chemical Industries, Inc. b I = insoluble S = soluble' D = dispersible. polyoxyethylene fatty ether mixture. After the addition of water was complete, the aqueous concentrate was allowed to cool to room temper- ature with stirring. The concentrate was allowed to stand overnight before the pearlescence or iridescence was evaluated. In systems with combinations of the polyoxyethylene ethers with either alcohols or acids, the concentration of each component was ap- proximately 0.05M, based upon the aqueous phase. This concentration assumes that the compounds have an average molecular weight as shown by their empirical formulas. The mol ratio of polyoxyethylene fatty ether to alcohol or acid therefore was 1:1. The concentrations on a weight per cent basis were as follows:

580 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Polyoxyethylene Fatty Ethers POE (4) lauryl ether, POE (2) cetyl ether, POE (2) stearyl ether POE (10) cetyl ether, POE (10) stearyl ether POE (23) lauryl ether, POE (20) cetyl ether, POE (20) stearyl ether Fatty Alcohols Fatty Acids Per cent 1.6-1.8 3.4-3.5 5.4-6.0 0.9-1.3 1.0-1.4 Composition of the Aerosol• Three low pressure propellants were used for the aerosols: Freon *)* 12/Freon 114 (15/85), isobutane, and blend of 72.2% Freon 12/Freon 114 (15/85) and 27.8% isobutane. The latter propellant blend has a calculated density of 1.0 g/cc, which is close to that of the aqueous phase. This mixture is referred to as the "Propellant Blend" in the report. Aerosols prepared with either Freon 12/Freon 114 (15/85) or the propel- lant blend had a composition of 90% aqueous phase and 10% propellant. Those prepared with isobutane had a composition of 95% aqueous phase and 5% propellant. Color Photographs The color photographs of the pearlescent concentrates and aerosols in the paper were made with an 8 X 10 Deardorf camera with a 4 X 5 back. The camera was equipped with a 14-inch commercial Ektar lens and used 4 X 5 Ektachrome and Ektacolor film. The samples were il- luminated with two 750-watt Bardwell and McGallister spots for strong side lights. The exposure was 1/10 second at f 16. RESULTS Optical Properties of the Aqueous Concentrates Variation in Components Polyoxyethylene (POE) Fatty Ether/Fatty Alcohol Combinations-- Eleven polyoxyethylene fatty ether surfactants were evaluated alone and in combination with lauryl, myristyl, cetyl, and stearyl alcohols. The optical properties of the aqueous concentrates prepared with these com- binations are listed in Table I. The degree of pearlescence or iridescence is indicated in Table I by the following rating scheme: * Freon © is Du Pont's registered trademark for its fiuorocarbons.