What is it?
Also known as glycerol or glycerine, glycerin is a colourless liquid found in all natural fats (whether animal or plant), including those in our own skin. It can also be manufactured synthetically.
What is it used for?
Glycerin is a humectant, meaning that it attracts moisture to the upper layer of the skin where it is applied. In this way it prevents dryness and scaling by maintaining the skin's barrier against the elements, and is often used to treat medical conditions like psoriasis and dermatitis, as well as dry skin. It can also be used to promote wound healing. As well as being used in skincare, glycerin is a common component of natural soaps due to its moisturising properties and its ability to cleanse gently.
What are the pros and cons of using it?
Glycerin is effective in preventing dryness and protecting and reinforcing skin's protective barrier. The potential downside comes because glycerin attracts moisture to the epidermis (the surface layers of the skin) from wherever it can find it most abundantly - so in humid environments it may draw from the external atmosphere, but in many cases it will draw up moisture from the deeper layers of the skin (the dermis) to the epidermis, where moisture is more easily lost. This still keeps the epidermis looking and feeling plumped and moisturised, but can compromise the hydration levels of the dermis. However this is why glycerin is best used when combined with other ingredients rather than in its pure form - for example in combination with occlusive emollients the risk of losing moisture is largely reduced, and with hydrating oils it can penetrate deeper and provide lasting moisture. Those suffering from very dry skin may find that glycerine dramatically improves their condition.
Which products can I find it in?
Since their main function is to promote and maintain hydration, glycerin is generally found in moisturisers and masks. Try Elemental Herbology Moisture Milk, Eve Lom Rescue Mask or Bakel Collagen Firming Serum.