If you’ve done your homework, you’ll know that skin exfoliation is essential for a glowing complexion because it gets rid of dull, dead skin cells. And this becomes even more important as we get older and the skin gets less efficient at shedding skin cells. Chemical exfoliants (a.k.a. liquid exfoliants, exfoliating liquids, exfoliating acids and leave-on exfoliants) are great products for sloughing off old skin cells and helping with a myriad of skin complaints. Let’s look at two categories of exfoliating acids which have flooded skincare shelves: AHAs and BHAs.
Physical vs. chemical exfoliation
There are two different methods of exfoliation: physical and chemical. Physical exfoliation, as the name suggests, refers to products which physically buff dead skin cells away - including things like face scrubs, exfoliating brushes and gloves. And then there’s chemical exfoliation - when acids (not as scary as they sound!) are applied to the skin to loosen dead skin cells. AHAs and BHAs fall under this type of exfoliation and are often used in chemical peels and a whole host of skincare products. So, how does an exfoliating acid work?
What are liquid exfoliants and how do they work?
AHAs and BHAs are both groups of exfoliating acids which break up the glue-like bonds between dead skin cells so they can easily lift away from the face. This reveals the fresh, new skin underneath that’s super soft and smooth. These chemical exfoliants improve skin tone and texture, smooth out fine lines and wrinkles, and keep pores nice and clean. Whether used at home or in a clinic, an exfoliating liquid can brighten the skin and keep it clear, smooth and youthful. But, AHAs and BHAs work in different ways - let’s dive in.
What are AHAs?
Alpha hydroxy acids (better known as AHAs) can either be synthetically made or derived from natural sources like milk and sugar cane. There are 6 different AHAs in total, including the famed glycolic acid as well as lactic and mandelic acid.
AHAs are skin sloughing powerhouses. They’re water-soluble (they dissolve in water) and are great at working at the top level of the skin, rather than sinking into deep layers. Best suited to dry, mature and sun-damaged skin types, these liquid exfoliators effectively treat surface issues like fine lines and wrinkles, discolouration and uneven skin texture. So, after use, your skin should feel silky smooth and look refined - yay!
What are BHAs?
When I’m talking about BHAs, I’m actually talking about just one type of BHA: salicylic acid. This is the most common BHA used in skincare products and is probably the one you’ll hear everyone else talking about.
Salicylic acid is derived from willow bark and can also be found in aspirin - so steer clear if you have an aspirin allergy. Like AHAs, BHA has great exfoliating properties, but it works a little differently. Still exfoliating the surface of the skin, BHA is oil-soluble, meaning it travels deeper into the skin than AHAs and is best for oily, combination and acne-prone skin types. This chemical exfoliant cuts through the skin’s sebum, working its way into the pores to dissolve dead skin cells and oil which can clog pores.
So, whereas AHAs give your skin surface-level exfoliation, BHA gives your skin deeper, pore-level exfoliation - this is definitely a win in my book!
Even though BHA has skin-clearing superpowers, it’s still a relatively gentle ingredient that’s even mild enough for sensitive skin. Don’t forget to whip out the moisturiser when using a BHA liquid exfoliant, though. This acid can be a bit drying!
At what stage in your skincare routine should you use AHAs and BHAs?
AHAs and BHA are best sandwiched between toners and serums. So, something like this: cleanser, toner, AHA/BHA, serum and moisturiser. Applying your AHA or BHA straight after cleansing and toning means it has direct contact with the skin and doesn’t have to fight its way through thick products.
It’s also really important to note that you should always wear sunscreen during the day when using an AHA or BHA. Whilst BHA doesn’t increase the skin’s sun sensitivity as much as AHAs, you need to wear SPF when using both (you should wear one every day anyway, of course!).
Can you combine AHAs and BHA?
This one’s not so easy to answer. It all comes down to what your skin can handle. Your skin might find combined AHA and BHA use too irritating, but other skin types can thrive off it. So, it’s all about trial and error - sorry if that’s not what you wanted to hear!
You might want to alternate between an AHA liquid exfoliant and a BHA one, changing it up daily. Or you might want to try one in the morning and one in the evening. Start slowly with a low percentage acid and see what your skin likes and what it doesn’t.
Okay, liquid exfoliation crash course complete!