I have a question for you: why does a tan disappear? I don’t realize the process. We all have top skin layer of the skin that became darker, it is epidermis, right? So, once it is tanned how it becomes light again?
The tan or pigmentation process occurs in the epidermis, but the epidermis replaces all its skin cells every 28-30 days. Cells in the inner portion of the top skin layer divide themselves and migrate to the surface, gradually die and slough off. Our skin cells contain melanin, and as a result of UV exposure, rise to the surface and flake off. A tan can be maintained only by repeated exposure to UV light.