How does fake tan work, and why does it sometimes smell ‘biscuity’?
The sugar-plus-amino acids combination involved in fake tanning is the same broad class of chemistry that happens in cooking. You are, in a sense, toast.
Fake tan, also known as sunless tanning, is a method of achieving a tan without exposing oneself to the harmful effects of ultraviolet (UV) radiation. This is achieved through a chemical reaction within the skin, rather than through direct pigment absorption. The main ingredient in fake tan products is dihydroxyacetone (DHA), a sugar molecule that is naturally present in our bodies.
Upon application, DHA penetrates the outermost layer of the skin, the stratum corneum, and reacts with the amino acids and proteins present in these cells. This chemical reaction leads to the formation of brown pigments that become trapped within the skin, giving the appearance of a tan. This process is chemically similar to the Maillard reaction, which is responsible for the browning of toasted bread, biscuits, and seared steaks.
The distinctive smell associated with fake tan is also due to this chemical reaction. As DHA interacts with amino acids, it produces volatile molecules such as aldehydes and ketones, which evaporate quickly and give off a scent that can be described as "biscuity". This smell tends to intensify when the skin is warm, such as after exercise or when sweat is present, as these conditions can heighten the evaporation of these odoriferous molecules.
In terms of color, DHA generally produces an orange-brown tone, particularly on individuals with fair skin. To achieve a more natural-looking tan, manufacturers often incorporate green or olive pigments into their products. These pigments neutralize the excess orange hue, resulting in a more even and realistic tan.
However, fake tan application is not without its challenges. A common issue is patchy application, particularly in areas with thicker, rougher, and drier skin, such as elbows, knuckles, ankles, and the base of palms. These areas contain more protein within the dead skin cells, making them more receptive to DHA's chemical reaction.
Furthermore, DHA only stains the outermost layer of skin, leading to uneven fading as these cells naturally slough off. Factors such as friction from clothing, sweat, dry skin, and variations in skin shedding rates can contribute to the "leopard print" fade that is often observed.
To improve the results of a fake tan, it is advisable to moisturize certain areas with an occlusive cream before application, which can help reduce DHA penetration. Additionally, exfoliating both before and after the tan application can help remove stained dead skin cells more evenly, thereby reducing the appearance of patchiness. However, it is essential to remember that the process takes time, and rushed attempts may result in uneven application, stronger smells, or unwanted orange tones.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
