EFFECT OF COCONUT OIL ON HAIR DAMAGE 179 PROTEIN LOSS IN uglg OF HAIR 240 200 160- 120- 80 40 0 227 ..................................... COCONUT OIL 145 139 145 140 SUN FLOWER COCONUT SUN FLOWER OIL OIL OIL PRE-WASH TYPES OF OILS POST-WASH BWITHOUT DWITH Figure 2. Comparison of protein loss from bleached hair. a beaker containing boiling distilled water. The hair tresses were immersed in it. This was not done to simulate any real-world process but in order to create extreme stressful conditions. This was primarily done to assess any impact on hair in water at high temperature, as Indian consumers largely use a hot water bath for hair. In the case of UV treatment, the hair tresses were exposed to simulated sunlight in a xenostat, wherein each hair tress was exposed at 50øC and 65% relative humidity for a period of 300 hr. The tresses were turned over during the period of exposure to attempt a uniform exposure of all fibers to the radiant source. In some cases hair tresses were treated with 0.2 ml of coconut oil/mineral oil/sunflower oil before exposure, with the oil spread uniformly across the hair tress before exposure to UV light. In a few cases, the treatment with oil was carried out after UV exposure. The tresses were stored at room temperature for 48 hr before they were subjected to protein loss determination. This was designed to simulate density of hair on scalp and scalp treatments. For the oil application, to each hair tress was applied 0.2 ml of oil (the quantity of oil normally applied by an Indian hair oil user). It was allowed to remain on the hair for at least 14 hr to simulate overnight application (the normal habit of the Indian consumer). These hair tresses were then subjected to both protein loss and WRI tests. The entire study involved samples of straight, curly, wavy, and permed hair of Indian origin. Because the number of variables was high, i.e., the type of oil, type of hair,

180 JOURNAL OF COSMETIC SCIENCE PROTEIN LOSS IN ug/g OF HAIR 360 - 320 - 280- 240 - 200 - 160 - 120 - 80- 306 40- 0 • COCONUT OIL I I I I I I SUNFLOWER COCONUT SUNFLOWER OIL OIL OIL PRE-WASH TYPES OF OILS POST-WASH l [] WITHOUT [] WITH Figure 3. Comparison of protein loss from hair treated with boiling water. sequence of oiling, the total number of oil applications, and the number of shampoo applications, the study had become quite complex in nature. In order to simplify the complexity of the experiment, i.e., to reduce cost, time, and energy without compro- mising on the quality of results, a statistical tool was selected, termed the Taguchi Design of Experimentation. This is a tool used in research and development of products in an engineering industry wherein, depending upon the levels and factors, an appro- priate design, either orthogonal array or factorial design, is selected. This helps to reduce the number of experiments without affecting the result. Using this statistical model, it was possible to complete the entire study in the stipulated time frame without losing vital information, as it cut the number of experiments to be conducted from 14400 to 800 (considering 25 hair tresses per variable). As the experiment was quite complex, we had to select the design of an orthogonal array, L32, to conduct the experiment. The design of experiment was as presented in Table I. The tresses were wetted under running tap water (28øC) and washed with a 20% solution of sodium laureth (3 moles of EO) sulfate (SLES). One milliliter of the solution was applied per tress, and the tresses were worked between fingers to produce a lather. Following this, they were extensively rinsed to remove all the SLES residues. After this treatment the tresses were subjected to the following investigations. Combing damage. The protein loss method of Sandhu and Robbins was used in the following manner. Each of the wet tresses was combed with a fine-tooth nylon comb (20-22 teeth/inch) 50 times, rather vigorously along the entire length of the tress on