People have been using cosmetics since the time of ancient civilizations. Women in ancient Egypt used kohl as eye shadow. Cleopatra supposedly bathed in milk for whiter, smoother skin. Later, during the medieval period, Greek women even used toxic lead carbonate to whiten their complexions just to be fashionable. Cosmetics have become an essential part of most people’s lives and manufacturers have made them a source of life. It is possible that all people, regardless of age, gender and culture, have used some type of cosmetic.
Cosmetics technically refer to substances or products intended to be applied to external parts of the body, including the teeth and mouth. Cosmetics are used to clean, to give a pleasant smell, to protect and to change the appearance. Regarding the chemistry of cosmetics, the usual ingredients or materials used in the manufacture of cosmetics are water, fragrances, emulsifiers, colorants, preservatives, pH stabilizers and thickeners.
Emulsion is a concept that most cosmetics are based on. It can be a few drops of oil in water or several drops of water in oil. Water and oil never mix, which is why emulsifiers are used in the cosmetic-making process. The emulsifiers prevent the water from separating with the oil and vice versa, so a homogeneous product with a uniform texture is obtained.
Preservatives are added to cosmetics to prevent the growth of microorganisms. The growth of bacteria or fungi can spoil the products and cause harm to the user. Commonly used cosmetic preservatives are tetrasodium EDTA, benzyl alcohol, and parabens. Polymers are examples of thickeners that are added to cosmetics to achieve the desired consistency. They can be natural (polysaccharides) or synthetic (polyethylene glycol). Polysaccharides are generally obtained from seaweed in the form of carrageenan which comes from red and brown seaweed.
pH stabilizers affect the acidity of cosmetics, color creates an attractive effect, and fragrances make cosmetics smell good. Moisturizers are cosmetic products used to treat dry, flaky skin. They prevent further loss of water or moisture from the skin (occlusion) and add substances to the skin that make it able to retain moisture (humectants). Occlusive moisturizers contain alcohol and some mineral oil. Moisturizing moisturizers have glycerin and fruit acids.
Surfactants added to soaps and shampoos explain the cleaning ability of cosmetic products. The usual surfactant molecules used in the manufacture of cosmetics are lipophilic (fat soluble) and hydrophilic (water soluble). Lipsticks are made with the concept of water solubility. It is made of water-insoluble dye, wax and non-volatile oil. Fake bronzers are cosmetic products that alter their color once they come into contact with the skin. Its active ingredient is a colorless dihydroxyacetone that changes color as a chemical reaction with amino acids in the upper layer of the skin. The color produced is permanent; however, the tan also sheds from the skin along with the constantly shedding skin cells.
The use of cosmetics must be done with care because they may contain ingredients that can be harmful to the skin. Some people are allergic to makeup and other cosmetic products. Chemicals added to cosmetics, such as fragrances and preservatives, can cause allergic dermatitis. Determine if the skin is prone to allergies; a patch test must first be performed.
