How do moisturisers work?

Our skin is made up of three distinct layers: the top or outer layer called the epidermis; the second layer called the dermis, which contains blood vessels, nerve endings, hair roots and sweat glands; and finally the subcutaneous fat layer containing larger blood vessels and nerves.

Moisturiser can play a key role in both adding water to the skin and keeping it hydrated.

Facial moisturisers are made up of oil-in-water emulsions consisting of tiny droplets of oil held in a watery base. To prevent the oil and water from separating or deteriorating, manufacturers add stabilising ingredients, such as emulsifiers and thickeners.

In order to help keep water in the skin, moisturisers contain substances called humectants. These are substances that are capable of attracting water and help to conserve the water in the skin.

A cosmetic moisturiser designed to encourage skin hydration will include water, humectants and emollients, blended with oils and emulsified to form a liquid or cream.

Adding moisturiser means that a liquid fills the air gap between dry skin flakes and skin rather than just air, this liquid has a closer refractive index to that of skin and as such helps to transmit light rather than reflect it. With increasing moisture levels, the stratum corneum becomes more translucent and this means more light can reach the lower layers of the skin.

This is responsible for the apparent enhancement of skin colour that is often visible the moment you apply a moisturiser.