348 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS bulk fiber properties, and grooming damage has been viewed by microscopy of the fiber surface. An important but largely unexplored possibility is that one treatment might predispose hair to even greater damage from a second treatment, or conversely, that one treatment could alleviate the damaging effects of another. The prime objective of an industry-wide research project at TRI is to explore methods of establishing the extent of damage from, among others, oxidative and reductive treatments. Damage to hair surfaces as a function of severity of these treatments has been measured using microfluorometry, scanning electron microscopy, and Wilhelmy bal- ance wettability. Changes in hair structure, or bulk properties, have been quantified via dye diffusion studies, amino acid analysis, mechanical properties evaluations, and fa- tigue behavior. These analytical techniques are discussed, and the effects of subsequent grooming treatments (combing, shampooing, and conditioning) in causing and allevi- ating secondary mechanical damage are explored. EXPERIMENTAL HAIR TREATMENTS Bleach treatments. Dark brown European hair from DeMeo Brothers Company, New York, was used. The segment near the root end, five inches long, was taken for use in this study. Bundles of hair were prepared, weighing 10 g each. The samples were rinsed extensively in deionized water. Two types of bleach treatment were performed: 6% solution of H202, at pH 10.2, and a bleach creme, containing a persulfate with a higher peroxide concentration and lower pH. A higher pH was chosen for the 6% H202 treatment to achieve optimal bleaching effects. All 6% H202 treatments were done at 21øC with a liquid:fiber ratio of 50:1. Hair samples were bleached in 6% H202 for 30 minutes, 1 hour, and 4 hours, with fresh solution every hour. In an effort to concentrate treatment effects near the fiber surface, a treatment involving multiple exposures (ten) of short duration (2 min) was included. Exhaustive rinsing followed all treatments. The 30 a minute wella bleach creme treatment was done at 2 IøC at a liquid ratio of 6:1. The bleach creme formulation contained 9% H202 at pH 8.6. Other contents of the bleach creme were ammonium persulfate, sodium silicate, sodium bicarbonate, EDTA, and Aerosil. Perm treatments. Three criteria were used in establishing conditions for perming untreated and moderately bleached (4 hours, 6% H202) hair. These were 1) the use of an ammonium thioglycolate perm with peroxide neutralizer, 2) the formation of tight curls, and 3) simulation of salon treatments. The information given by Zviak (7) indicated that for untreated hair, 1.0 M thioglycolate at pH 9.5 would be appropriate, with 0.5 M thioglycolate at the same pH for the bleached hair sample. A hydrogen peroxide solution (3%) at pH 7.0 was used as the neutralizer. Tresses of 0.5 g were secured on small perm rods (¾8" diameter), using water mist and papers to moisten the hair lock. The rod-mounted tresses were soaked for 20 minutes at room temperature in a large excess of 1.0 M ammonium thioglycolate at pH 9.5 for previously untreated hair and in 0.5 M thioglycolate at pH 9.5 for moderately bleached

EVALUATION OF HAIR DAMAGE 349 hair. Rinsing for 25 minutes in running deionized water was followed by 10 minutes in 3% H202 at pH 7. After a ten-minute rinse under running water, the tresses were removed from the rods and rinsed for two more minutes, followed by blow drying. This cycle was repeated to produce tresses with one, two, and three perm treatments. Grooming simulation treatments. We have simulated grooming processes by sub- jecting the hair to a number of cycles of combing, shampooing, shampooing plus combing, and shampooing plus conditioner treatment plus combing. Untreated hair and samples with two levels of oxidative damage were selected for evaluation. Each hair bundle was 13 cm long and contained about 1375 hairs. Four grooming sequences were applied, as outlined in Table I. Each grooming sequence was performed on wet hair, and was repeated for ten cycles, each time after drying several hours under ambient conditions. Combing was done by hand, with 25 strokes through each of the four sides of the hair bundle. The total time of combing was 1.25 minutes per 100 strokes. The standard "Ace" comb of brown nylon had 65 tines in 11 cm length. Wet hair was blotted between paper towels prior to combing. Shampoo was applied to the wet hair swatch with a 1 ½m 3 syringe and was massaged into the hair by hand for two minutes. The hair swatch was then rinsed for two minutes under running deionized (DI) water. Conditioner (1 ½m 3) was applied to wet hair and distributed manually for 30 seconds, then left on for 1.5 minutes, for a total exposure time of two minutes. The hair swatch was rinsed under running DI water for two minutes. The experimental shampoo and conditioner samples were formulated by Colgate- Palmolive Company. Their compositions are shown in Table II. Table I Sample Identification Bleach treatment Grooming sequence Code assignment Untreated hair 10 X 2' in 6% H202 4 hours in 6% H202 None U0 Combing U 1 Shampooing U2 Shampooing/combing U3 Shampooing/conditioning/combing U4 None 2B0 Combing 2B 1 Shampooing 2B2 Shampooing/combing 2B 3 Shampooing/conditioning/combing 2B4 None 4B0 Combing 4B 1 Shampooing 4B2 Shampooing/combing 4B 3 Shampooing/conditioning/combing 4B4