Clarence R. Robbins

Amino Acid Composition of Human Hair

Samples of hair from five different female Caucasians were selected, while attempting to eliminate or minimize variables introduced by factors, suggested in previous literature, related to genetics, malnutrition, and cosmetic alteration, to analyze for 18 amino acids. The objective was to determine if human hair from such a similarly sampled group differs in composition from individual to individual. Significant differences were found for 9 of the 18 amino acids analyzed at the α = 0.01 level, however, the percent deviations for 16 of the amino acids were within ± 6%. Comparison of these samples of hair with pooled dark brown hair, from female Causasians, and purchased from a hair dealer, indicated a note-worthy difference only in the cystine content. Comparison of these data from human hair with that from 64s Merino wool indicates substantial differences between cystine, glycine, tyrosine, and phenylalanine. Statistically significant differences were suggested for other amino acids between Merino wool and human hair; however, the magnitude of the numerical differences, in these instances, was substantially lower than for the above mentioned four amino acids. Weathering effects in human hair were also explored, suggesting degradation to the amino acid residues of cystine, tyrosine, hysine, and histedine by the elements.

Infrared Analysis of Oxidized Keratins

was postulated. Strasheim and Buijs [4], using differential infrared spectroscopy, confirmed the results of Weston and further indicated that infrared spectra of , wool powder that had been reacted under milder conditions with peracetic acid for 5 min and 2% reagent contained in addition to sulfonate bands, absorptions at 9.2 po and 9.4,A which have subsequently been assigned to cystine monoxide and dioxide residues by Savige and Maclaren [2]. ’ Strasheim and Buijs [4] also examined two reactions of 10% hydrogen peroxide with powdered wool at an unspecified pH. Judging from the results, however, these systems were on the acid side of the pH scale. Severe treatment under these conditions (5 days) produced a modified wool powder that absorbed infrared radiation at 8.5 p. and 9.6 ~&dquo; indicating sulfonate. Shorter reaction times (24 hr) produced material that absorbed at 9.2 ~, and 9.4 ~, in addition to the 8.5 ~, and 9.6 , absorption bands. These additional absorptions are presumably due to cystine monoxide residues. Prior to this latter publication, Stein and Guarnaccio [3] described their infrared examination of the reactions of hydrogen peroxide and sodium hypochlorite at vari-

The Physical Properties and Cosmetic Behavior of Hair

One of the roadblocks to both communication between the cosmetic scientist and consumers and scientific investigations in hair care has been the lack of meaningful definitions for the important cosmetic properties of hair conditioning, hair body, and manageability. A definition for hair conditioning has emerged that allows this important cosmetic property to be approached by considering ease of combing as the first boundary condition. In addition, progress has been made for the definitions of hair body and manageability over the past two decades. Admittedly, there is still room for improvement in the understanding of these hair assembly characteristics, but even more progress awaits those important properties associated with hair feel, such as clean hair feel, conditioned feel, and dryness-oiliness.

Interactions of Shampoo and Creme Rinse Ingredients with Human Hair

The two primary actions of shampoos and hair conditioning products with hair involve (1) cleaning soils including lipid (sebaceous) and other types from hair, and (2) sorption or binding of ingredients to hair. The first section of this chapter is concerned with the different types of soil found on hair; their origin and the ease or difficulty in their removal; methods to evaluate hair cleaning; the perception of hair cleaning; and shampoo lather as it relates to cleaning. The second section is concerned with the attachment and the affinity of surfactant/conditioning-type molecules to hair including the theory of sorption considering both whole-fiber and surface studies. Damaging effects to hair caused by shampooing and hair grooming, including the actions of combing and brushing hair, are also considered. A brief introduction into the subject of dandruff concludes this chapter.

Morphological and Macromolecular Structure

Human hair is a keratin-containing appendage that grows from large cavities or sacs called follicles. Hair follicles extend from the surface of the skin through the stratum corneum and the epidermis into the dermis (Figure 1–1).

Bleaching Human Hair

The composition of amino acid residues in bleached hair and in hydroly-sates of oxidized keratin fibers is described in Chapter 2 and also in publications by Zahn [1,2], Robbins et al. [3–6], Maclaren et al. [7,8], and Alter and Bit-Alkis [9]. Although, several questions remain unanswered, especially with regard to the structures and reactions of hair pigments [10–14], general features about the chemical structure of hair and its reactions with bleach products have been relatively well described using the language of physical-organic chemistry.

Polymers and Polymer Chemistry in Hair Products

Polymers have become increasingly important components of cosmetics over the past few decades. The more important uses of polymers are as primary ingredients or adjuncts in shampoos, conditioning products, styling products (lotions and gels), mousses, and hair sprays. Polymers have been used to condition hair [1,2] and to improve the substantivity of other ingredients to hair [3,4]; to improve combing [1], manageability [1, 2], body [5], and curl retention [2,6,7]; to thicken formulations [8,9]; and to improve emulsion stability [8].

Interactions of Shampoo and Conditioning Ingredients with Human Hair

According to legend, the word “shampoo”, is derived from a Hindustani word meaning “to squeeze.” Shampoos have a long and varied history. However, hair conditioners were not widely used until the mid-twentieth century following the introduction of “cold” permanent wave-type products that exacerbated combing problems and damaged the hair.

Reducing Human Hair

The primary reactions involved in permanent-waving, straightening (relaxing), and depilation of human hair begin with reduction of the disulfide bond. In permanent-waving and hair straightening, reduced hair is stressed, that is, curled or combed straight, while molecular reorientation takes place primarily through a disulfide—mercaptan interchange process. Neutralization is then achieved either through mild oxidation or treatment with alkali (for some sulfite treatments).