The majority of self-tanning* (sunless tanning) products work via a similar mechanism; they use dihydroxyacetone (DHA) to stimulate a chemical reaction in the outer layers of the skin that generates a brown pigment, a “melanoidin”**. The effect is darker appearance, a tan, and that’s a big business!
But, the reaction is complicated. DHA is unstable, the substrates are biological tissue and vary not only from person to person but also by body location and by other variables such as the health and hydration of the tissue. The longevity and evenness of the tan depends on flattening the effect of these variables, whilst simultaneously improving the penetration of the chemical. Oh, and the reaction (a Maillaird reaction) produces a distinct odour.
Therefore the quest for the perfect self tanning product is a competitive marketplace with new formulations, additives, application methodologies and pre-treatment regimes being trialled, often empirically.
In a recent project, Danielle O’Loughlin and myself (Biologists) teamed up with Josh Turner (Chemist, working as a KTP associate)and a fellow UoLiverpool faculty member Tom McDonald (Chemists) and with PZ Cussons, makers of St Tropez premium self-tanning range, to work on the Science behind the reaction. Much of the findings are proprietary, informing new product design as we speak, they can’t be shared here yet.
However, part of the work involved finding out what was already understood about the process. Josh and Danielle scoured and collated all the published material about the self-tan reaction from chemical, biological and commercial perspectives. They then created an extremely useful article that brings each of these topics together. The result is a really nice, one-stop overview of the current thinking on self-tanning from each of these different angles. It is written in a quite accessible way so that It should be a valuable resource for anyone entering this area, irrespective of discipline.
If you want to know more about self-tanning, this is the place to go.
That article “In search of the perfect tan; chemical activity, biological effects, business considerations and consumer implications of dihydroxyacetone sunless tanning products” is out now. Available HERE for free.
*self-tan is different from fake tan. Self tan is a brown pigment*** that takes time to form and will last for a while. Fake tan is a dye that lasts until it is washed off.
**Melanoidins are quite different from melanin, the brown pigment expressed naturally in the inner layers of the skin.
*** (yes a footnote to a footnote) Although self-tan and natural tans look similar, the self-tan melanoidins don’t provide much ultraviolet protection whereas melanin does. You should always use SPF in conjunction with any self tan!
While you are here, you might be interested in our work on sun protection:
LaNts and Laminins 
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