A guide to the exfoliating acids you need in your skincare routine

Skin’s life cycle

Our skin has a natural renewal cycle and, by design, sheds dead skin cells every 28 days. The cycle starts with plump new cells, formed at the lowest levels of the skin, that migrate their way to the surface layer. The cells, which have now matured, die and shed (this is called ‘desquamation’), making way for fresh new cells.

We need a continual supply of new cells to keep our skin strong, hydrated and resilient, and to maintain the health of our skin barrier (which provides protection from microbial attack, environmental assault, mechanical damage and dehydration).

Desquamation slows down as we age. Plus, disruptors – such as hormones, stress, diet, sun damage or other environmental factors – can obstruct this natural process. The skin doesn’t shed rapidly enough, which causes a build-up of dead cells and can lead to skin roughness, dullness, unevenness, discolouration, blocked pores, blemishes or acne. Enter the use of exfoliants as a staple part of your skincare routine…

Benefits of exfoliation

  • Promotes glowing skin: By removing the build-up of dead cells that cause skin dullness or sallowness, exfoliation promotes cell renewal to reveal skin that is softer, brighter, fresher and more radiant looking.
  • Clears pores: While cleansers eliminate everyday impurities and bacteria, exfoliation goes deeper. It clears dead skin cells, excess oil and other debris that can clog the pores and lead to blackheads, whiteheads or breakouts.
  • Improves skin’s texture and tone: Accumulated dead cells eventually cluster together, resulting in rough patches, discolouration and an uneven tone. Exfoliation breaks down these clumps, which smooths the skin’s surface and gives it a more uniform appearance.
  • Anti-ageing: Exfoliation can help support collagen synthesis – promoting skin elasticity and plumpness, minimising the appearance of fine lines and wrinkles, and giving the complexion a more youthful, renewed appearance.
  • Enhances product absorption: Think of exfoliation as creating a clean canvass onto which your other products can do their job effectively. By removing dead skin cells, exfoliation clears the path for your skin to properly absorb the nourishing, hydrating and moisturising benefits of serums and moisturisers.

Acid exfoliants

There are several exfoliator types:

  • Physical exfoliants are abrasives that deliver a scrubbing action and can come in the form of grainy bits or particles inside a product, such beads or granules, or via a tool, such as brushes or wash cloths.
  • Acid exfoliants (also known as chemical exfoliants) don’t manually remove the skin and come with no friction. Both exfoliant types have their benefits, but acid exfoliants are generally milder.Acid exfoliants (have three main categories: alpha hydroxy acids (AHAs) beta hydroxy acids (BHAs) and poly hydroxy acids (PHAs). Although part of the same family, they work in different ways.

1. Alpha hydroxy acids – AHAs

AHAs are naturally occurring chemical compounds. They are the largest and most popular group of acids in skincare. They are water-soluble and have a small molecule size, which means that they work deeper and faster.
AHAs are useful to address the signs of ageing, fine lines, surface wrinkles, pigmentation, enlarged pores, roughness and uneven skin tone. AHAs attract water molecules, helping to lock in moisture so that skin is hydrated, smooth and radiant.
There are multiple AHAs – tartaric, malic, citric and mandelic acids – but the most commonly used are glycolic acid and lactic acid. These two have similarities (they both ‘dissolve the glue’ that holds binds skin cells together, so that the cells loosen and come away easily), but there are also some differences.

  • Glycolic acid: BA naturally occurring acid, glycolic acid is derived from sugar cane. (although it can be created synthetically in a lab). Glycolic acid is the most researched (and potent) AHA and is considered a ‘holy grail’ by skin experts. It has the smallest molecule size, which means that it offers deep exfoliation and can produce fast results. It has also hydrating properties. It’s particularly ideal for improving the signs of ageing, sun-damage, fine lines, wrinkles, discolouration and the skin’s overall texture and tone. Having antibacterial properties, it can also be beneficial to acne-prone skin.

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  • Lactic acid: A natural by-product of plant and dairy fermentation (although it can be created synthetically in a lab) lactic acid is one of the milder AHAs. It’s a skin-identical ingredient and its unique structure helps to improve moisture retention, so that the skin stays hydrated (it’s more moisturising than glycolic acid). The molecule size is larger than glycolic acid, so that it remains closer to the skin’s surface (polishing and firming). Working to improve the skin’s barrier, lactic acid can also help to reduce fine lines and disclouration. It’s ideal for dry, dehydrated or sun-damaged skin.

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2. Beta hydroxy acids – BHA

In skincare, the term BHA almost always refers to Salicylic acid. Its molecule size is larger than glycolic acid or lactic acid and its main function is to clear congestion. Derived from willow tree bark, it exfoliates the surface of the skin and clears bacteria and grime. However, because it’s oil-soluble (while AHAs are water-soluble), it can also penetrate deep inside the pores, where it removes excess sebum, dead skin cells and other trapped impurities.

Very often combined with other exfoliating ingredients to provide maximum benefit, salicylic acid also has anti-inflammatory properties, soothes irritated skin and helps to reduce redness. It helps to prevent future breakouts and is particularly ideal for oily, blemish-prone skin or mild acne (blackheads, whiteheads and small pimples).

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3. Poly hydroxy acids – PHAs

PHAs are known as the ‘next generation’ of chemical exfoliants (the most common are gluconolactone, galactosen and lactobionic acid). PHAS have a larger molecule structure than AHAs and BHAs, which means that they don’t work as deeply or quickly as other chemical exfoliants; however, they are still very effective. They promote hydration and can help the skin maintain moisture with less risk of irritation. PHAs don’t cause sun-sensitivity, although you should still always use an SPF! They have anti-inflammatory and antioxidant benefits too. The main difference between PHAs and other exfoliating acids is that their much gentler nature makes them ideal for sensitive skin.

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Please remember: Whichever acid exfoliant/s you choose, start gradually and don’t overdo it. You should already be using a sunscreen daily, but as acid exfoliants can cause sun sensitivity, it’s even more important to apply an SPF30 (at least) during the day.


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