A person’s face reveals personality, health and character, and it is that part of ourselves by which we are recognised. The face is covered in skin and the outermost layer of the skin’s epidermis is the stratum corneum (SC).
Healthy SC is a versatile material that combines the functional property of being an effective transport barrier and the material properties of being soft, strong and sufficiently pliable to tolerate deformation from physical strain and stress.
Keeping skin in good condition is part of the recognised function of cosmetics, and keeping it in good condition means keeping it properly moisturised, which is the focus of this feature.
The SC is approximately 10-15μm thick and comprises corneocytes embedded in a multi-lamellar lipid matrix in a fashion often described as a ‘bricks-and-mortar’ structure.
Water evaporates through skin to the external environment due to the water vapour pressure gradient on both sides of the skin barrier. It is referred to as transepidermal water loss (TEWL).