Exfoliation 101 Part 2: Physical Exfoliation Vs. Chemical Exfoliation

If you haven’t already read part 1 of this series, I’d strongly suggest reading it before you proceed. If you have though, let’s get right into it. There are two main ways to exfoliate: mechanical and chemical.

Mechanical or physical exfoliation

This involves using scrubs, or abrasive tools such as sponges, face cloths or cleansing brushes, to buff away the top layer of the skin. Physical exfoliation can be gentle or harsh depending on the scrub or tool used to exfoliate and the force applied while doing it. Scrubs and tools with smooth edges are gentler than those with rough edges.

In the current world of physical exfoliants however, the worst ones are unfortunately, the most common. Case in point: St. Ives Apricot Scrub in commercially available options, and sugar and salt scrubs in DIY options. Sugar, salt, and crushed seeds, such as those used by St. Ives have abrasive edges that create small scratches in the skin. While usually too small to be seen with the naked eye - unless you’ve scrubbed especially aggressively - these are a form of injury, or damage, to the skin and result in inflammation. When these scrubs are used regularly, this damage accumulates leading to longer term issues such as breakouts, sensitivity and premature ageing. Abrasive physical scrubs also predispose you to chances of infection, and are able to spread infection to other areas of the skin if you already have it, as in the case of acne.

If you do opt for physical scrubs however, there are some gentle options available that you can leverage instead. These include jojoba beads, ground oatmeal and peeling gels, where peeling gels are products that roll up to form scrubbing fibres when you massage them onto your skin. Plastic micro beads are a gentle option as well, but I’ve left them out of my recommendations because of their negative impact on the environment.

When using physical exfoliants, always massage gently and in small circles to avoid damaging your skin. If you’re using a peeling gel, use less water to get the most out of it.

While physical exfoliation imparts a lower chance of allergy or irritation if performed correctly, especially if your skin is very sensitive, it only works on the uppermost layers of the skin and doesn’t result in even exfoliation. It is also easy to mess up by for e.g., using something too abrasive, scrubbing the same area for too long and using too much pressure. Unlike chemical exfoliation, it doesn't help with acne and isn’t as effective for skin concerns such as pigmentation and skin ageing either. Physical exfoliation thus, is not my preferred type of exfoliation.

Chemical exfoliation

Chemical exfoliation entails the use of acids, enzymes and other similar ingredients to loosen the bonds between dead cells and allow them to shed off more easily. Chemical exfoliants work evenly on the skin and frequently also have other benefits, discussed in more detail later, beyond just getting rid of dead skin cells. They include skincare acids such as alpha, beta and poly hydroxy acids, and enzymes. A lot of people lump retinoids into the exfoliant category as well. While retinoids have the ability to speed up skin cell turnover, they are not exfoliants and do not have the ability to exfoliate dead cells from the skin’s surface.

Despite their many benefits, chemical exfoliants do pose some risk if used incorrectly. It is best to be aware of these risks so you can make the most out of them. I’ll guide you around their proper use in later sections.

Risks associated with the incorrect use of chemical exfoliants:

  • Exacerbation of the skin concerns that you’re trying to treat if you don’t protect your skin from the sun while using them. Chemical exfoliants make the skin more photosensitive and must always be used with SPF.

  • Reactions and sensitivity. Chemical exfoliants are potent ingredients. Always start slowly and build up to see how much your skin is able to tolerate to avoid an adverse reaction. Even for an experienced user the temptation to overuse them because of their immediate results can at times be hard to resist. Don’t do it however, since this won’t result in anything more than redness, sensitivity, burning and irritation.

Hydroxy Acids

Hydroxy acids come in many different product formats, and include alpha hydroxy acids, beta hydroxy acid (the acid here isn’t plural since salicylic acid is the only beta hydroxy acid that’s presently used in skin care) and poly hydroxy acids.

Hydroxy acids are extremely effective exfoliants. They result in a visibly softer, brighter and more even complexion, often from the first use, depending on the strength of the product used. They also have antioxidant and humectant properties and help reverse epidermal and dermal markers of photoaging in the skin including pigmentation, fine lines and wrinkles. They act on the skin’s surface and depending on the molecular size of the acid used, are even able to penetrate through to deeper layers of the skin. This penetration stimulates skin renewal and collagen synthesis, and speeds up skin cell turnover - something that tends to slow down as we age - resulting in skin that looks and feels younger. A study found that treating skin with AHAs resulted in a 25% increase in skin thickness, improved quality of elastic fibres and increased density of collagen.

Also a hydroxy acid, salicylic acid - BHA - differs somewhat in its characteristics from AHAs. The key difference lies in the fact that while AHAs are only able to dissolve in water, BHA has limited water solubility, but is soluble in oil and thus able to penetrate into the pore where it exfoliates the pore lining and dissolves clogs. It is also antimicrobial, and anti-inflammatory. These properties allow it to reduce the appearance of enlarged pores, and treat and prevent acne. It’s anti-inflammatory properties also make it beneficial for several other skin conditions, including ageing, that activate inflammatory pathways.

Poly hydroxy acids (PHAs), which include compounds like lactobionic acid, galactose and gluconolactone are similar to AHAs. They also work by exfoliating dead cells on the skin’s surface but have larger molecules that aren’t able to go as deep into the skin making them less potent but gentler and more suitable for sensitive skin types that might not be able to tolerate AHAs. Like AHAs, they also have antioxidant and humectant properties, but don’t result in photosensitivity to the same degree. They also help reduce glycation in the skin, a process that involves sugar attaching itself to skin collagen and weakening it. Since PHAs are gentler ingredients, they can even be tried by people with eczema and rosacea who might not be able to tolerate AHAs.


Protein digesting enzymes used in cosmetics come from fruits and vegetables. Common ones include bromelain (from pineapples), papain (from papayas), and actinidin (from kiwis). They come in wash off formats and the fruits or vegetables they come from can even be leveraged to create DIY masks provided that they haven’t been heat treated, since enzymes are sensitive to heat. Enzyme-containing products should be left off for up to 15 minutes and then washed off.

Enzymes work by breaking down proteins, including keratin in the skin’s outer layers, thus helping dead skin to slough off more easily resulting in the usual benefits of exfoliation: softer, smoother skin that has more even tone and texture. Enzyme exfoliation is that it is gentle, yet effective, and tends to be safe even for individuals with sensitive skin who aren’t able to tolerate AHAs and BHAs well. However, since they’re gentler than AHAs and BHA, they aren’t as effective and give less dramatic results.

Relevant products