So how do these products make us brown?
The skin is composed of two layers. The epidermis is the outer layer visible to us, and underneath this is what is called the dermis.
After the self tan product has been rubbed in all the reactions that bring about a colour occur in the epidermis, specifically in the stratum corneum. The skin cells in this layer are dead. When the active ingredient (DHA) comes into contact with the amino acids contained in the epidermis' skin cells a reaction follows that produces a brown pigment known as melanoidin. This pigment is connected to the proteins in our skin by lysine chains. DHA however, does not enter past the stratum corneum. Products more often than not also contain erythrulose. This is a natural occurring sugar that helps give a subtly more realistic tone to the skin.
However, our skin takes a lot of wear and tear and it has no choice but to regenerate itself. For this reason colour from a bottle or a canister gradually fades and further applications are therefore necessary.
These products very rarely contain any sun filters to protect the skin from exposure to the sun, and in no way help the body to produce Vitamin D. A link however does exist in the absorption spectra between melanin (what causes a real tan to develop) and melanoidins which steers the belief that fake tans offer an equivalent protection from the sun as SPF 2 - which is too low.
Need some advice on application and dealing with streaking??What are the Pros and Cons of This Option?
Firstly let us take a look at the positive aspects using a self tan:
Just like most things in life though we have to learn to take the good with the bad: