26 Mar 2017

Exfoliation 201: Chemical Exfoliation, AHA and BHA

Chemical exfoliation is a new thing for me. In fact, most Asian women only rely on scrub and deep-cleansing mask to exfoliate their skin. All of my friends that I spoke to were clueless about chemical exfoliation. And they were extremely concerned about putting acids on their skin, since acids are normally associated with skin damage. But after researching further, I found that acids can be your good friends for a younger and brighter looking complexion if it is used correctly. I hope that this article will give you a general idea about chemical exfoliation and perhaps even encourage you to jump on the bandwagon of acid treatment.

As we have discussed in Exfoliation 101, exfoliation is the key to brighter, smoother and younger-looking skin. But physical exfoliants like scrub and gommage peel are inappropriate for daily uses. Hence, our smart beauticians bring us this new innovation called chemical exfoliants. Chemical exfoliation, most commonly present itself in the forms of AHA and BHA, is the use of mild acids to clear up the buildup of dead skin cells on your skin surface and within your pores. If done properly, chemical exfoliation also carries long-term skin benefits to reduce hyperpigmentation, breakouts, wrinkles, and pores size. You can read this article to find out more about the science behind chemical exfoliation.

There are two major types of chemical exfoliants:

Alpha Hydroxy Acids (AHA)


AHA is targeted for dry, flaky, aging and pigmented skin. This is the ingredient that will improve your skin tone and texture. It works to loosen the bonds between your dead skin cells and encourage faster cellular renewal of the skin. As a result, your skin will appear brighter, evener, and firmer. It is important to keep in mind that sunscreen is a must whenever you are using AHA products. It is quite logical. Imagine what will happen if you don’t cover your wound when you accidentally cut yourself. Definitely that area will be painful if you expose it to heat or water. AHA works in a similar way. It will increase your skin sensitivity to UV light hence you must always remember to use a sunscreen when you are using AHA products.

AHA works as a water-binding agent in low concentrations (less than 3%). It will only play its role as an exfoliating agent under the condition of a pH level of 3-4 and a concentration of 4% and higher. As such, if you see AHA like glycolic acid, lactic acid and mandelic acid in your products, don’t simply assume that it will exfoliate your skin before knowing its pH level and concentration. You can find out more about the importance of pH for acid treatments here.

Let’s look at some of the AHA products I have tried in the past:

  • Belif First Aid Transforming Peel-Off Mask | Review
  • Cosrx AHA 7 Whitehead Power Liquid | Review
  • Dr. Wu Intensive Renewal Serum with 18% Mandelic Acid
  • Hanaka Intensive Renewal Facial Mask | Full Review
  • Neogen Bio-Peel Gauze Peeling Wine

All these are AHA ingredients containing exfoliating products. Cosrx AHA 7 Whitehead Power Liquid is a skin treatment that you use after your toning step. Dab a small amount on concerned area or all over the face and then continue with your skincare routine. I have been using this product for several months now and am convinced that it will work to reduce the appearance of stubborn whiteheads on my nose. Do you know those rice-looking whiteheads that always stick to your nose whenever you are not having proper rest and diet? And they are extremely difficult to remove without causing a lot of hassles and damages to your skin. But this product will slowly yet gently work its way into your pores and get rid of these whiteheads naturally. It will also reduce the formation of whiteheads by constantly shedding off your old skin cells that blocked these whiteheads from being eliminated from your body naturally.

Next, I have Belif First Aid Transforming Peel-Off Mask, which in my opinion is kinda obsolete. I have read good review on this product but somehow didn’t really feel the same when used it on my face. It is kinda gentle and non-abrasive but I don’t see a lot of differences after using it. It does make my skin appears brighter and clearer but my whiteheads are still there and never go away. It is also kinda expensive to maintain because you will need at least 4-5ml for each use. As such, a jar of this can only last you for 10-15 uses. Cost-effectiveness wise, I would still go for Cosrx.

And there is Neogen Bio-Peel Gauze Peeling Wine. This is a unique product. It is made of two-sided pads soaked in exfoliating essence. You use the rougher side to swipe across your skin and the smoother side to pat the essence in. It is convenient and innovative, in my opinion. I do notice that my pores appear smaller and my skin is smoother and refreshed after using this. However, since I only start to use it, I need to use it for longer to see if there is any long-term benefit from it. I will come back with more review soon.

I want to talk very briefly about Dr. Wu Intensive Renewal Serum with 18% Mandelic Acid and Hanaka Intensive Renewal Facial Mask. They are both mandelic acid infused products. I have used both products and am really unimpressed. Dr. Wu has the reputation of being an effective skin renewing serum among the Taiwanese beauty community. It contains 18% mandelic acid to exfoliate and regenerate skin cells. A blogger even claims that this is one of the saviors for her freckles problem. But as for me, I really dislike its consistency, which is a bit irritating and oily when applied topically. It is even more unpleasant than Cosrx and I didn’t see any results after using up the miniature I got as a gift with purchase from SASA hence I don’t think I will repurchase in the future. I have done a full review on Hanaka mask, which is another “meh” without any practical skincare benefits.


  • A’pieu Aqua Peeling Cotton Swab | Full Review
  • It’s Skin Clear Skin Peeling Swab | Full Review
  • Mediheal Peelosoft XP 10% Black Pore Shot
  • Mediheal Peelosoft XP 9% Clear Shot Cotton Swab
  • Nighttingale Toning Eraser Original (pH 4.0)
  • Primary Raw DoYou 2-Step Milk Peeling Kit | Full Review
  • REME+G Home Peeling 2-Step Brightening Kit 
  • REME+G Home Peeling 3-Step Aqua Kit | Full Review
  • The Saem Express Beauty 1,2,3 Kit – Perfect Peel & Clean
  • The Saem Express Beauty 1,2,3 Kit - Peel & V Firming | Full Review
  • The Saem Express Beauty Milk Peel Cotton Swab | Full Review
  • Tony Moly Skin Clinic 3 Step- Micro Peel Swab Whitening Kit



We also have a bunch of masks that come with AHA-infusing cotton swabs which allows you to enjoy the treatment benefit of masks and exfoliating benefit of peeling swab. This trend is relatively new in Korea. REME+G is one of the first brands that brings in the concept of aqua peel in the form of mask. And then we slowly see other brands like Holika Holika, The Saem, Tony Moly, A’pieu, It’s Skin are coming up with similar products. I have tried cotton swabs from The Saem, A’pieu, Primary Raw, It’s Skin and REME+G and must say that I am most impressed with the performance of The Saem, REME+G and Primary Raw. They are really fun to work with and you can see good results the next day after you wake up. They are not cheap though so you can also look opt for Cosrx AHA 7 Whitehead Power Liquid which will last you for longer and at much affordable cost. You can read more about aqua-peel, cotton swab and milk-peel here.

Next, I want to talk about BHA, the saviour for individuals with oily, combination, and acne-prone skin.

Beta Hydroxy Acids (BHA)


BHA is used in skincare to fight off blackhead, blemish, and acne. Unlike AHA which is water-soluble, BHA is oil-soluble which allows it to penetrate deeper into the skin to clear out all gunk and dirt that has been built up inside. As such, use BHA first before using AHA if you want to use them on the same day. And since BHA might be quite drying for your skin, always properly hydrate or moisturize your skin after using BHA products. My boyfriend who has been using Cosrx BHA Blackhead Power Liquid without a proper moisturizer suffered massive flakiness all over his skin. So he has no acne, just showered in dead skin cells flakes.
  • Cosrx BHA Blackhead Power Liquid | Review
  • LJH Probiotic Sleeping Mask
  • Cosrx One Step Pimple Clear Pad | Review


I don’t own a lot of BHA products because I don’t really have acne and blackhead problems. But my bf is a typical dehydrated-turned oily skin with severely clogged pores and loads of blackheads. So, he has been using the Cosrx BHA Blackhead Power Liquid and LJH Probiotic Sleeping Mask over the past few months with good results. Cosrx BHA Blackhead Power Liquid is very effective against blackhead without drying out or further irritating the skin. As for LJH mask, he has not been very clear about it. The only comment he has on that mask is that it makes him more comfortable. Of course, he also suffers a lot less breakouts ever since adding BHA products into his routine. For someone without a lot of acne and pores concern like me, Cosrx One Step Pimple Clear Pad is all I need to keep my skin soft and smooth. It is convenient, effective, and reasonably priced. It contains AHA and BHA so it is great for those no-acid-treatment days.

Wait Time between AHA and BHA Products

Finally, I want to talk about the wait time between AHA and BHA products that many people have asked me about. Of course, AHA and BHA are very pH-dependent so it makes sense to assume that your skin has to be at certain pH to allow it to take effect. But since AHA and BHA products I use don’t really state or require the wait time, it makes me wonder is it necessary to wait 10-20 minutes between those steps.

I have done some research on the topics and found that the answer is NO. You do not have to wait 10-20 minutes between acid treatments because our skin doesn’t respond to minor changes in pH of products we use on our skin that fast. This makes pH of products irrelevant. Paula’s Choice, which is considered one of the earliest to formulate AHA and BHA products also denies the need for a wait time. Cosrx Advisor I spoke to earlier even told me that the pH of a cleanser doesn’t really matter when it comes to cleansing because our skin doesn’t respond to the pH of products as quickly as we thought. She also denied the need for wait time between the Cosrx Power Liquids. The official information also never requires you to do so. You can read more about the science behind wait time of chemical exfoliants here.

I know this argument will raise a lot of controversies, but like I said, I am a researcher not a scientist so I am just pointing out my findings, not proven or disproven anything.

Personally, I have used AHA and BHA in both ways, with and without wait time.  I found that these products work just the same with and without wait time. In addition, putting extra wait time between products only make my skin even irritable, dry and itchy, especially after AHA treatment. Applying a moisturizer immediately after will mitigate that condition. As such, I belong to the “no-wait-time” category since I found that waiting that 15-20 minutes actually makes my skin worse, not better.

I guess these are all I want to talk about chemical exfoliation. There is a close relative to AHA known as PHA now available in the market. I have just purchased a PHA containing product recently and will talk about this ingredient in more details soon!


[Disclaimer] This is NOT a sponsored review. Products are purchased with my own money. All copy right of contents and images in this article is strictly mine.
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