Chemistry of Cosmetics prepared by J. CHEM. EDUC. Staff
0 Cosmetics: Something for Everyone
We have space here to describe only a few of the many inter?sting chemical principles and strategies used in the cosmetics industry.
the epidermis of the concentration of melanin. the dark skin pigment, Figurr 2. Thi; increase is [he result of photr~hrmiral oxidnticms that can occur in huth the living and nimlivinr cells of the epidermis. Prolonged exposure to tKe sun also increases the thickness of the nonliving or keratinized layer. T h e dermis contains the working components of the skin-the sensory nerves, hlwd vessels, sweat glands and hair follicles, or root hags. Each hair follicle has several sebaceous glands associated with it. These glands excrete an oily material called sehum, which passes through the pores. The oiliness of the skin and hair are a result of these excretions. Sehum is a mixture of fats and waxes plus about five percent fatty acids. Hence it is slightly acidic. Pimples are inflammations caused by the irritation of sehum spreading on the skin. Normally, washing with soap and water should neutralize the acid and remove sehum from the skin.
0 Some Chemistry of Skin
0 The Structure of Hair
Cosmetics comprise all substances, preparations, treatments and operations used to improve the appearance of a person. They include: a) Skin care products such as face and hand creams and lotions, soaps, certain detergents, other bath products, depilatories, shaving formulations, and suntanning preparations. b) Hair care oroducts such as shamuoos. lotions, oils. fixatives.
e) Perfumes, colognes, and deodorants
Much of the chemistry of cosmetics centers on the nature ~f the skin and the hair. As we know, the skin encloses the body, preventing some internal materials from escaping while dlowing others to pass through. At the same time, it keeps most external materials out. The skin regulates body temperature by controlling the escape of water, as sweat. It also regulates the penetration of sunlight-allowing enough to penetrate to make the quantities of Vitamin D needed in hone Formation, hut keeping out quantities that could damage mderlying tissue. Black skin, for example, transmits less light than white skin. Therefore, hlack skinned persons living in northern climes may he subject to more hone deformities than ~ h i t eliving s in these areas. The skin also senses and transmits Information on temperature and pressure of the environment. As Figure 1shows, the skin has a number of components, livided, for convenience, into three layers-an outer layer, ;he epidermis, which covers the true skin or dermis, below which is the subcutaneous tissue, largely fatty material. The epidermis contains the pigment-producing cells that letermine the shade or color of the skin. It consists of a deep ayer of growing cells with an outer layer of dead cells. This oellnnt. \Vhen soraved on the hair.. the .oroduct forms druolets The purpose of cleansing creams and lotions is the removal of facial makeup, surface grime and oil from face and throat. bf resin which; when dry, impart support and stiffeking Properly formulated, these products will quickly and effiproperties to individual hair fibers,and form junctions beciently remove face powder, rouge, foundation bases, cake tween adjacent or intersecting hair fibers, creating a semirigid makeup, and lipstick. Some products also remove eye makeup. network. One of the most widely used film formers is polyA basic formulation for cleansing creams is: beeswax 16.7%; vinylpyrrolidone, or PVP. mineral oil 50.0%, borax 0.83%; water 32%. After emulsifying, References perfume is added and the product is packaged. The beeswax Ralsam. M. S., and Sayarin. E.. IEditurI "Cmrnetir?: Scienceand Technulow. Vuh. I. 1I.III." and mineral oil are perhaps the chief cleansing agents for the Wiley-Intarscience. New York. 1972. nonpolar face makeups and lipsticks. Selinger. R.."Chemistry in the Market Place." Australian NafionalUniurnity Prear, Cmberra, 197R.Chapter4. Hand creams and lotions are formulated to provide care for Volume 55, Number 12, December 1978 1 803
