Chemical Reaction
The most effective self-tanning lotions contain 3 to 5 percent DHA or dihydroxyacetone, a colorless sugar. When applied to the skin, the DHA in the tanning lotion reacts with the proteins or amino acids in the topmost layer of skin cells. This reaction produces melanoidins or yellow-brown pigments, coloring the skin a tan color. As the body naturally sheds dead skin cells, the coloring provided by the self tanning lotion fades. The tan produced by a self-tanning lotion lasts an average of 5 days. Spray-on self-tanning lotions may provide longer-lasting results than lotions applied directly to the skin. Tanning products for daily use contain a lower percentage of DHA, about 1 percent.
Application
Before applying a self-tanning lotion, you should shower and use an exfoliating cleanser. This will make your self tan last longer and increase the evenness of application. If the lotion will be applied to a part of the body that your normally shave, such as your legs, shave before application. Experts are divided as to whether or not you should moisturize your skin before applying a self-tanning lotion---some experts believe hydration makes for more even application, while others believe it interferes with the necessary chemical reaction. Follow the instructions on the product you choose. Women should not apply make-up before using self-tanning products. After the self-tanning lotion is applied, avoid showering or perspiring for at least 6 hours to give the product time to absorb fully. Many self-tanning lotions contain coloring or a bronzer. Not only does this provide an immediate result, but it makes it easier to see where the lotion has been applied.
Protection
Some self-tanning lotions provide sunscreen protection. This protection is effective, however, only for a short period of time and only if you go into the sun soon after application of the lotion. The tan provided by a self-tanning lotion provides limited protection against sun exposure. Therefore, if you use self-tanning lotions, you still need to use sunscreen. Choose an SPF based on your level of exposure and reapply regularly, especially after swimming, perspiring, or toweling off.
