GELS AND SPRAYS IN TWO-POINT STIFFNESS TEST 347 PANEL TEST The panel test was performed in 2007 in Ludwigshafen, Germany as a double-blind test. Twenty-eight responses were counted. The questionnaire asked for the direct comparision of the two gels with three ranks: better, similar, or worse (4). HALF-SIDE TEST The preparation of the hair and the evaluation were performed in a climate room at 20°C/65% relative humidity. Ca. 3.8 g of spray was applied on each side of the model head. In direct comparision, two different products were evaluated by three trained lab technicians. Focus was on estimation of the stiffness of the hair style after drying of the hair spray overnight. The hair setting was rated by numbers 4 (no setting), 3 (poor setting), 2 (medium setting), and 1 (high setting). RESULTS AND DISCUSSION The results of the standard three-point stiffness test on round-shaped hair strands after application of styling gel formulations (see Table I) are depicted in Figure 5. Discrepances between hand grading and stiffness are obvious. Formulations 1 and 2 are characterized by a low stiffness ( 150 cN) but with a quite good hand grading of formulation 1. The lowest correlation between the objective bending test and hand grading occurs with Figure 2. Measuring device: Texture Analyzer TA.XTPlus. Figure 3. Prepared fl at hair strain between two glass plates at a defi ned position.
JOURNAL OF COSMETIC SCIENCE 348 formulation 7. The high stiffness of 350 cN could not confi rmed by the hand-rating panel. Hand grading gave only a score of 2. This low degree of correlation is still not fully understood. Obviously there is strong evidence that the round-shaped hair geometry is not practically useful to assess the setting effect on hair. Figure 5. Result of the three-point stiffness test after gel application (striped-grey data set: BASF formula- tions full-grey data set: market products). Hand grading: 1 = highest, 4 = lowest. Breaking of the strains by hand. For formulas, see Table I. Figure 4. Force displacement curve of the bending stiffness test.
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