Elta ® Tan Sunless Tanning Lotion reacts with the keratin (protein) in the upper layers of the skin to quickly produce a natural, healthy-looking tan for most skin tones. Not all Tanning Lotion (s) are created equal. Elta Tan Sunless Tanning lotion works indoors in about 4 hours, without sun. Tans faster and with more natural color than other products, with no artificial dyes.