If you've ever seen a sliced apple turn from white to brown, you've seen how spray-tanning products work on your skin.
Natural chemicals cause the inside of the apple to turn brown when it's exposed to air. The naturally occurring chemical dihydroxyacetone, commonly known as DHA, does the same thing to your skin. DHA is the main ingredient in sunless tanning sprays. In fact, the Skin Cancer Foundation warns against using any sunless tanning product that does not list DHA as the active ingredient [source: Bank].
DHA is a colorless sugar derived from plants such as sugar beets. It has been used to treat medical problems such as skin-pigmentation disorders for more than 50 years. It's also been approved by the U.S. FDA for cosmetic use for decades. It was first used in a tanning product by Coppertone in the 1960s, although that early attempt tended to turn people orange. DHA products have improved since then, partly because the refining process is better.
DHA has an enzymatic reaction with the amino acids in the outer layer, or epidermis (stratum corneum), of the skin, causing the dead skin cells to turn temporarily dark. By contrast, the sun's rays and the UV lights used in tanning beds penetrate into the deepest layers of skin. That's why they cause lasting damage.
The effects of the DHA are temporary. You are constantly shedding dead skin cells, so within a few days, your "tan" will be gone. The best you can expect from spray tanning is color that lasts about a week. Many products advise a new application in three days to keep a "tan" current.
Just as it takes the apple a while to turn brown, so can it take several hours for the DHA to darken your skin. That's one reason some products also include a temporary dye or bronzing agent: Customers want to see immediate results. Unlike the darkening caused by DHA, the dye will wash off the first time you shower -- or "run" when you sweat. Another common ingredient in spray-tanning products today is erythrulose, also a natural sugar, which gets some credit for the more natural (not orange) color of newer spray-tanning products. Manufacturers also add botanicals, moisturizers and aloe vera to help the skin absorb the tanning solution quickly and avoid excessive dryness.
Want professionals to spray on your tan? Read on to learn about the options.