Shampoos and soaps are products that usually contain some kind of fragrance and clean the skin by the use of surface-active agents, or surfactants. These surfactants are molecules that have both lipophilic and hydrophilic, or fat soluble and water soluble parts. The fat soluble part of the product clings to the oil and dirt as the water soluble part allows the lipophilic part to be washed away. Detergents for dishes and clothes work in pretty much the same way but will have different ingredients that make them more harsh for use on hard, solid surfaces. It is usually not a good idea to try and use these detergents on the body and hair, for it can lead to irritation.
Lipstick is another cosmetic product that contains hydrophilic properties. They are manufactured by combining wax, a non-volatile oil such as beeswax with castor oil, and water. The combination produces a thick substance that is water-insoluble and spreads easily on the lips. Because of its lipophilic properties, lipstick won’t dissolve on the lips when exposed to saliva or liquid from drinks. Other lipsticks will have a dye in them that react to amino acids on the top layer of the skin. This makes the the product appear blue or green in the container and change to red when applied to the lips.
When water is lost on the top layer of dead skin cells faster than the living cells under them can absorb the moisture our skin becomes dry. This is when we need the help of a moisturizer. When the skin becomes dry and scaly, moisturizers can assist by preventing further water loss, known as occlusion, and by adding humectants, substances that increase the hydrophilic properties of the skin. Humectant moisturizers contain substances such as alpha hydroxy acids or glycerine and add moisture to the top layer of skin while occlusive moisturizers form a waterproof layer over the skin that reduces moisture and allows the body’s natural rehydration process to return the layer to a normal level.
