Insights into shaving and its impact on skin

Abstract

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 ...

Towards a body hair atlas of women of caucasian ethnicity

“…3.5 hairs/cm 2 ) is significantly greater than of upper arm and upper leg. Interestingly, the hair density of axilla (12.4 hairs/cm 2 ) and intimate area (14.7 hairs/cm 2 ) is much higher than in all other investigated body areas but still more than 20 times less compared to the average scalp hair density which is typically around 300 hairs/cm² in Caucasians of younger age, although declining with ageing [11].…”

“…This requires higher razor forces and shorter razor/removal intervals as compared with other body regions and this increases the risk for skin problems like irritations. Furthermore, the angle of emerging axilla and intimate area hair is significantly smaller than of all other body areas, which reduces the contact angle for razor blades and increases the risk of ingrowing hair . Consequently, after shaving in these body areas, additional treatments like exfoliating scrubbing to smooth the skin surface and to dislodge trapped hairs as well as anti‐bacterial treatments are necessary to avoid painful ingrown hair and its inflammatory consequences .…”

Male skin care: Shaving and moisturization needs

“…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). Thus, it is not surprising to find that most nicks and cuts as well as soreness and irritation occur on the male neck (14). Of the shave sites, the male neck region is most challenging due to a lower hair emersion angle and rougher skin topography (14).…”

“…Blades are typically machined to 0.075-mm thickness with a radius on the blade tip to around 25 nm (14). The features that ensure this occurs include the development of a leading guard element at the front of the cartridge that protects the skin from the blades.…”

“…Further complicating the 1000-fold differential is the actual anatomy of the skin on both the face and neck. Of the shave sites, the male neck region is most challenging due to a lower hair emersion angle and rougher skin topography (14). In some instances, this appears as a mounding or volcanic like structure rising up around the emerging hair follicle (FIG.…”