Structural characteristics and mechanical behaviour of beard hair

Thozhur, Sumeetra M.; Crocombe, A.D.; Smith, Paul A.; Cowley, Kevin D.; Mullier, N.

doi:10.1007/s10853-005-3648-2

Cited by 17 publications

(15 citation statements)

References 12 publications

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“…The elastic modulus of dry beard hair has been measured to be around 3-4 GPa, which decreases to around 1-2 GPa when the hair is fully hydrated. 1,2 The deformation of skin, in comparison, is highly nonlinear and viscoelastic, with skin approximated to have an initial modulus of the order of 1 MPa. 3,4 This results in a relative ratio of around 1000 for the stiffness of hair ⁄skin, resulting in hairs being relatively loosely supported in facial tissue.…”

Section: The Shaving Challengementioning

confidence: 99%

Insights into shaving and its impact on skin

Cowley¹,

Vanoosthuyze²

2012

British Journal of Dermatology

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SummaryMale grooming has its roots in antiquity. Control and styling of facial hair has invariably required the development and use of metal instrumentation. Once crude and unreliable, it has latterly become sophisticated and subject to intense research and development at the highest scientific level. This paper describes how male grooming is being impacted by improvements in fundamental understanding of male skin. Skin issues associated with poor hair removal approaches are common, but are often overlooked or their aetiology misunderstood by patients and physicians. By incorporating advanced scientific measurement and imaging technology into clinical testing, insights are being gained into both the common concerns which men express and optimal solutions for these concerns. Specific aspects such as the study of nicks and cuts and the identification and release of trapped hairs are discussed. Finally, details are presented on how the individual elements of technologically advanced razors play a role in managing the skin and hair, highlighting further the complexity of the shaving process.The process of shaving represents a complex compromise, in balancing robust removal of hair against minimizing impact to the sensitive skin substrate. Men typically articulate their ideal shave as one which maximizes the closeness of the shave, but does not compromise on comfort or skin irritation. Close examination of the physiology of the male beard reveals that it can be likened to tough fibres embedded in a soft jelly-like matrix (Fig. 1). This discrepancy in the relative properties of skin and hair results in a significant challenge when attempting to manipulate hairs for optimal, safe removal during shaving. The shaving challengeThe elastic modulus of dry beard hair has been measured to be around 3-4 GPa, which decreases to around 1-2 GPa when the hair is fully hydrated.1,2 The deformation of skin, in comparison, is highly nonlinear and viscoelastic, with skin approximated to have an initial modulus of the order of 1 MPa. 3,4This results in a relative ratio of around 1000 for the stiffness of hair ⁄skin, resulting in hairs being relatively loosely supported in facial tissue. As a blade engages and cuts a hair, the hair can be seen to be translated in the plane of the skin due to the lack of support, resulting in a sensation of tug and pull. 5 Similarly, application of hair cutting forces along the axial direction of the hair shaft has been shown to result in hair extension from the hair follicle, due to distortion of the soft material between the hair root and the skin surface layers. 6The cross-sectional size and profile of each individual hair are known to vary between individuals and across the facial sites of a single individual.2 Beard hairs are typically larger and more elliptical than scalp hairs 7 and consequently are observed frequently to rotate in their follicles to present the major axis of the hair to the advancing blade edge. Thus, it can be seen that hairs are highly mobile within the skin in both rotational ...

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Section: The Shaving Challengementioning

confidence: 99%

Insights into shaving and its impact on skin

Cowley¹,

Vanoosthuyze²

2012

British Journal of Dermatology

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“…This value was chosen to be within the range typically used when studying keratin materials, between 5.5-833 mm/s (Bonser and Purslow, 1995;Kania et al, 2009;Li et al, 2010;Thozhur et al, 2006;Tombolato et al, 2010). Only one of these studies examined how Young's modulus varied with strain rate; the effect was generally small.…”

Section: Mechanical Testingmentioning

confidence: 99%

Variation in Young's modulus along the length of a rat vibrissa

Quist

Faruqi

Hartmann

2011

Journal of Biomechanics

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“…For example, male facial hair fibers have been found to have an elastic bending modulus of 3-4 GPa, whereas the more viscoelastic nature of skin has a reduced modulus of 1 MPa (12,13). This is due in part to the need to remove the hair shaft as close to the surface of the skin while ensuring there is no collateral damage to the softer skin surface.…”

Section: Male Grooming -Evolution Of Solutionsmentioning

confidence: 99%

“…This is due in part to the need to remove the hair shaft as close to the surface of the skin while ensuring there is no collateral damage to the softer skin surface. For example, male facial hair fibers have been found to have an elastic bending modulus of 3-4 GPa, whereas the more viscoelastic nature of skin has a reduced modulus of 1 MPa (12,13). Further complicating the 1000-fold differential is the actual anatomy of the skin on both the face and neck.…”

Section: Male Grooming -Evolution Of Solutionsmentioning

confidence: 99%

Male skin care: Shaving and moisturization needs

Oblong

2012

Dermatol Ther

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Historically, most cosmetic and medical cosmetic research has been focused on the female consumer. Advancements in the development of grooming instruments as well as changing consumer habits and attitudes toward male cosmetic skin care needs support the need to develop a deeper understanding of male skin biology and how that can be used to improve the quality of life relative to societal interactions. Male skin biology has been found to have unique properties that are distinct from females and have a significant impact on the way males groom and maintain their overall appearance. Research to date has found that male skin has a different response profile to such environmental insults as UV, heat, and stress that is based not on just differences in cosmetic or dermatological product usage but also on underlying biological differences. These differences are discussed with the implications to a broader understanding of male facial skin care needs that spans from daily grooming practices to overall health status that impacts higher incidence rate of skin cancer among males. This highlights that male skin care has a holistic need to ensure proper grooming and sunscreen moisturizer usage.

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Structural characteristics and mechanical behaviour of beard hair

Cited by 17 publications

References 12 publications

Insights into shaving and its impact on skin

Insights into shaving and its impact on skin

Variation in Young's modulus along the length of a rat vibrissa

Male skin care: Shaving and moisturization needs

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