The Mechanics of Fracture of Human Hair

Swift, J. A.

doi:10.1046/j.1467-2494.1999.186942.x

Cited by 55 publications

(53 citation statements)

References 5 publications

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“…The rate of attrition of the scale edges is, however, highly dependent upon an individual's lifestyle and grooming habits. The loss is accelerated sufficiently following application of such chemical treatments as bleaching, permanent waving, oxidative dyeing, or by excessive exposure to sunlight, such that the cuticle covering may be completely removed at the hair's extremity, leaving the central shaft vulnerable to further breakdown (Swift 1999b).…”

Section: Introductionmentioning

confidence: 99%

Atomic force microscopy of human hair

Swift

Smith

2000

Scanning

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Summary:The atomic force microscope (AFM) was used to investigate the surface architecture of the entire lengths of cleaned human head hairs. Many features previously seen with the scanning electron microscope (SEM) were identified. However, the AFM has provided much greater detail and, in particular, the hair's cuticular surfaces appear not to be as smooth as had been previously supposed. A consistent feature was of step discontinuities or "ghosts" on the scale surfaces. These delineated the original location of each overlying scale before its edge had been chipped away. There was a change in the longitudinal angular presentation of the surfaces about each ghost. This means the distal ends of each cuticle cell have been synthesised in the follicle to be thicker than where that same cuticle cell is bounded on both sides by other cuticle cells. The undamaged outer cuticular surfaces at the root end of each hair were covered everywhere by longitudinal ridges (striations). Where the hair surface was worn, the striations terminated at a scale edge ghost. The ridges were approximately 9 nm high and were in parallel array with a lateral repeat spacing of about 350 nm. The striations are evidently formed on the outer surface of each cuticle cell following earlier contact in the hair follicle with the inner root sheath. The study of stained transverse sections of hairs in the transmission electron microscope (TEM) is suggested as a means for throwing some light on the underlying structure and chemistry of the striations. Finally, our AFM studies have revealed that the surface of the freshly emergent hair gradually changes over a distance of about 20 mm and that the surface of the hair for most of its length is quite different from that near the root. This is likely to be of import to those engaged in the hair toiletries industry.

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Section: Introductionmentioning

confidence: 99%

Atomic force microscopy of human hair

Swift

Smith

2000

Scanning

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“…As shown in Figure 10, the diffusion area of CYS was observed ranging from the fiber surface to 6.65 m below the fiber surface. Considering the fact that the cuticle region is about 5 m (a sheet of cuticle is approximately 0.5 m thick, and layers were overlapped with 5 to 10 sheets of cuticle 2,17 ), CYS remained in the cuticle region of the virgin human hair, and CYS for the most part did not penetrate the cortex region. This experiment suggests the reason why virgin human hair treated with CYS was less damaged than the virgin human hair treated with TG is that CYS does not penetrate into the cortex region of the virgin human hair at pH 9.0.…”

Section: Diffusion Behavior Of Tg Tl and Cys Into Human Hairmentioning

confidence: 99%

Diffusion behavior of reducing agents into keratin fibers using microspectrophotometry

Kuzuhara¹,

Hori

2004

J of Applied Polymer Sci

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ABSTRACT:To investigate the penetration of thioglycolic acid (TG), thiolactic acid (TL), and l-cysteine (CYS), into keratin fibers, cross-sectional samples of virgin white human hair treated with TG, TL, and CYS were prepared. A new method for analyzing the diffusion behavior of reducing agents into human hair was developed. The diffusion pattern of reducing agents into human hair, which cannot be determined by optical microscopy, can be determined by the method developed. The method involves treating virgin hair fibers with TG, TL, and CYS. After the treatment, the crosssectioned hair samples were dyed with methylene blue and the cross-sectional intensity scans were measured at a wavelength of 664 nm ( max of methylene blue) with a microspectrophotometer. The three different diffusion patterns from the three reducing agents were obtained. The penetration of TG and TL into virgin human hair clearly increased by increasing the treatment time and pH. On the other hand, the penetration of CYS was less than TG and TL (CYS could not penetrate into the cortex region of the virgin human hair). Also, the diffusion pattern of TG showed Fickian type characteristics. The apparent diffusion coefficient of TG into human hair at pH 9.0 determined from the TG concentration profile was found to be 10 Ϫ9 cm 2 /s. On the other hand, the apparent diffusion coefficient of TG into human hair at pH 7.0 was 10 Ϫ10 cm 2 /s, and thus, the apparent diffusion coefficient of TG depended on the pH of the TG solution. From these experiments, we have concluded that the diffusion patterns of the three reducing agents in this study depended on the electrostatic interaction between the human hair and the reducing agents.

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“…Very important are the repetitive everyday practices of combing and brushing. This strips the cuticle and results in fragmentation of the exposed cortex and fraying of the hair tips [3] . Many shaft dysplasias, common as inherited weaknesses of the hair shaft, have been described in normal hair under external aggravating conditions [4][5][6][7][8][9][10] : trichoclasis, a 'greenstick' fracture of the hair shaft with intact cuticle [6] , trichoschisis, a clean transverse fracture [9] , trichoptilosis, split ends [7] , central trichoptilosis (or pseudopili bifurcati) [8] and trichorrhexis nodosa [10] , have all been described as arising from vigorous brushing, hairdresser's manipulations or other physical or chemical trauma.…”

Section: Hair Structure Abnormalities Attributed To Exogenous Agentsmentioning

confidence: 99%

“…However, combing and brushing cause acute bending of the fi bers against each other contributing to the process of hair fracture, and not tension alone [77] . Negroid hair is particularly susceptible because of its high frequency of kinks along the fi ber axis and its ribbon-like cross sectional shape.…”

Section: Traction Of Hairmentioning

confidence: 99%

Exogenous Factors in Hair Disorders

Horev¹

2004

Exog Dermatol

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The health and beauty of human hair have immeasurable psychological importance. Hair structure and its cycle are influenced by intentionally or nonintentionally delivered factors such as grooming, heat styling, chemical agents and climatic exposure. All of these factors are capable of causing loss of hair color and luster, harshness, stiffness, weakness, brittleness and flyaway, transient loss of hair or scarring alopecia. In this review we describe the effects of various exogenous agents on hair, including hair cosmetics, traction, heat, water, solar radiation and X-irradiation.

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The Mechanics of Fracture of Human Hair

Cited by 55 publications

References 5 publications

Atomic force microscopy of human hair

Atomic force microscopy of human hair

Diffusion behavior of reducing agents into keratin fibers using microspectrophotometry

Exogenous Factors in Hair Disorders

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