66 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Statistical analysis is presented that compares conventional Curl Retention with Twist Retention measurements. A high degree of correlation between the two tests is ob- served. Differences between hair fixatives will be shown to develop'at a faster rate with TRA, giving correlation after short time intervals, to long-term Curl Retention analysis. Parameters of Twist Retention testing are discussed, including swatch size, degree of twist of swatch, air flow rate, fixative pickup, and effect of shampooing upon perfor- mance. A strain gauge apparatus is used for precisely determining the amount of fixative on the sample swatch. EXPERIMENTAL FIXATIVE FORMULATIONS Eight hair fixative formulations (Table I) were prepared from 0.50 to 4.00 per cent by weight in andydrous ethanol. Neutralization was carried out, if needed, to the manu- facturer's recommended level with 2-amine 2-methyl 1-propanel (AMP). Three of the formulations (D1, El, E2) were resins in conjunction with typical plasti- cizers at a level of 15 per cent on the resin solids. TORSIONAL BRAID ANALYZER A Torsional Braid Analyzer (6), Model 100B 1 • was utilized for measurement of Twist Retention (Fig. 1). The sample is suspended in the center of an enclosed vertical cylin- drical chamber, fixed in place at the top and free to rotate at the bottom. A schematic TABLE I FIXATIVE FORMULATIONS RESIN A - poly-vinyl pyrrolidone (molecular weight 40,000) RESIN B - vinyl acetate (70)/vinyl pyrrolidone (30) copolymer RESIN C - (vinyl acetate/crotomc acid/vinyl neodecanoate terpolymer) neutrahzed 80% pf its avatlable acidity with 2.amine 2- methyl1. propanel (AMP) RESIN D - (butyl half ester of methyl vinyl ether/ malelc anhydride copolymer) neutralized 7% of •ts available acidity wtth AMP RESIN E - octylacrylamlde/acrylates/butyl amine ethyl methacrylate polymer neutralized 90% of its available acidity with AMP FORMULATION - D1 - Resm D plus 15% on the resin weight, of poly-propylene glycol (26) oleate FORMULATION - E1 - Resin E plus 15% on the resin weight, of poly-propylene glycol (26) oleate FORMULATION - E2 - Resin E plus 15% on the resin weight, of poly-ethylene oxide (molecular weight 1000) •Chemical Instruments Corp., P.O. Box 399, Woodbury, NJ 08096.

EVALUATION OF HAIR FIXATIVES 67 Figure 1. Torsional Braid Analyzer cross-sectional diagram of this apparatus (Fig. 2) shows the sample chamber isolated from the outside environment. Any desired atmosphere of gas may be passed through the chamber, entering at the top. A linear-with-angle optical transmission disc (transducer) converts the torsional motion of the sample into a convenient electrical readout. An optical system is used in which a ••_ •.,4..,.TWO WAY SOLENOID ON MANDREL SUPPORTING ROD ,!, EXTENDER ROD COOLING INPUT ............. •-z.J,?l, I I MAGNETIC STABILIZER •) ,ig LIGHT SOURCE Figure 2. Schematic diagram of the Torsional Braid Analyzer