The goal of a sunless tanning product is to deliver DHA to the skin in a way that provides an even, natural looking tan color (64). To achieve this, there are three important considerations. First, the formulation must ensure that the DHA itself remains stable; otherwise, the product will develop an unpleasant brown color and burnt caramel off-odor in the package, and the sunless tan provided by the product will be compromised. Stability is achieved, for example, by a combination of an optimal product pH and avoiding materials in the formula that react with DHA, such as amine functional materials and certain pigments.
Second, the product needs to spread the DHA very uniformly on the skin to provide an even, streak-free tanned color. To achieve good spreading, a number of new product forms beyond traditional sunless tanning lotions have been introduced, including sunless tanning sprays, foams (mousses), and wipes. Finally, the sunless tanning product needs to absorb into the skin and dry quickly, to make it easier and more convenient to achieve a good tan. Getting dressed or going to bed while a sunless tanning product has not fully absorbed into the skin can lead to uneven color as well as stained fabrics. Thus, creating faster absorbing/drying sunless tanning formulas, like the sprays and foams mentioned above, ensures best results.
Importantly, while all of this sunless tanning product technology has yielded significantly improved sunless tanning products over the early sunless tanning products of 20-plus years ago, the reality is that achieving a good, even sunless tan still depends a great deal on factors other than the product. For example, proper skin preparation via cleansing
and exfoliation is critical to achieving an even, lasting sunless tan. Also the reaction between DHA and the skin takes several hours. Avoiding sweating, swimming, or showering for several hours after product application is also important to ensure best results. Finally, since DHA tends to more intensely color skin that has thicker, more compact outer layers, it is important to wash the hands after applying product to avoid dark brown stained palms.