The fingernail or nail plate is a complex matrix comprising closely packed keratinized epithelial cells or onychocytes—cross-linked cysteine bond matrix proteins containing inorganic elements such as sulfur as well as calcium, sodium, iron, aluminum, copper, etc. In addition, the water content of a normal nail plate is typically between 10–30%, which acts as a plasticizer to the nail plate, providing increased flexibility. The thin layer of skin or cuticle at the base of fingernails protects the nail root and bed from environmental irritants and microorganisms from entering the nail fold surrounding the nail.
Various formulas have been developed to treat and decorate the cuticle and nail area. Moisturizers, exfoliants and serums, among others, target the cuticle to improve the condition of this thin layer of skin. Meanwhile, products such as strengtheners, ridge fillers and polishes are applied to protect, strengthen, smooth and impart color to the nail plate. The present discussion will focus on the components of typical nail polish formulations.