There are four dominant factors that determine your Skin Type. These factors are: oily vs. dry, sensitive vs. resistant, pigmented vs. non-pigmented, and wrinkled vs. tight. The key factors interact to determine the skin’s appearance, problems, needs, and vulnerabilities, and therefore dictate the kinds of products, ingredients, and treatments useful to address them. To get started, let me introduce you to some basics about the skin.
THE BIOLOGY OF THE SKIN
The top layer of the skin, called the epidermis, is made up of four distinct layers. When you look at someone’s skin, you see the very top layer, made up of cells that reflect light. When that top layer is smooth, it reflects light evenly so that the skin looks more uniform and radiant than it does when the surface is rougher.
At the lowest portion of the epidermis are “mother cells,” called basal cells, which produce all the other skin cells. They divide into “daughter cells,” which rise up to the higher levels of the epidermis. As they travel, they age and eventually die, so that the top layer consists of dead cells which naturally exfoliate off in a process called the “cell cycle,” which can take anywhere from twenty-six to forty-two days. Between the third and eighth decades of life, the cell cycle slows from 30 to 50 percent of its pace in youth. That means that older skin renews itself much more slowly, forming a rough surface of cells, rather than a smooth surface. The uppermost cells contain a natural moisturizing factor (NMF), which holds moisture. The body responds to a dry environment by producing more NMF, but it takes several days for production to rev up, so your skin may become quite dehydrated before help comes. That’s why it’s important to moisturize your skin in any dry environment. Substances released by the cells in the middle of the epidermis form a protective film made of lipids (fats) that surrounds skin cells and helps keep the skin hydrated. Your fingers and toes contain fewer lipids and are therefore not as “watertight” as your legs, which is why your fingers and toes look shriveled after immersion in water but your legs do not. Your skin cracks in cold weather because the chilled lipids become stiffer and less able to adjust to movement. The goal of the best moisturizers is to increase the amount of these important lipids, helping your skin to hold moisture.