CHEMICAL PEELS 101: Acid Types

Updated: Apr 14



Which chemical acid peel is correct for your skin type? What is your skin type? And, how do chemical acid peels work?


Chemical peels are one of the most effective antiaging tools I use in my yearly skincare routine.

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Naturally, different chemical peels vary in treatment, strength, and downtime. The overall concept of skin improvement via a chemical peel is to remove the outer layers of skin in order to reveal younger, tighter, more glowy skin.

Just like with microneedling, a chemical peel is a controlled wound that stimulates cell renewal and regenerates healthier layers of skin below the surface.


With so many factors, how do you decide which chemical peel to do?



My favorite acid peel is TCA. This is a strong acid and it will cause you to shed skin. This type of peel is shocking for most to experience and observe since your skin falls off in sheets for nearly a week. TCA is very effective at treating sun spots, wrinkles, pore size, and overall, it rejuvenates your complexion. Although TCA is my favorite acid peel, I use other acids all year long. So let's dig deep and look at all acids, what are their benefits, and how best to use them.


ACID PEEL VIDEOS

I have many peel video's up on YouTube chronicling my experiences and I have them grouped into an Acid Peel Playlist


TYPES OF ACIDS

FIRST: there are 3 categories of Hydroxy Acids:

  • Alpha-Hydroxy Acids

  • Beta-Hydroxy Acids

  • Poly-Hydroxy Acids (we will cover these in another post)

SECOND: Chemical peels are broken into 6 different types:

  1. Alpha Hydroxy Acids (AHA's)

  2. Beta Hydroxy Acids (BHA's)

  3. Trichloroacetic Acid (TCA)

  4. Blended Peels: Self-neutralizing

  5. Blended Peels: Requiring Neutralization

Chemical peels rely on acids to penetrate, coagulate proteins, denature, and overall clear outer skin cells to reveal more radiant-looking skin.


CHEMICAL PEEL BOOK

I have found this book to be very helpful when looking at peel options and how to best use them on myself.


HOW DOES THIS WORK?


The mechanism for skin releasing and falling off due to a chemical peel is called desquamation and it has to do with the above blue = called Desmosome.


There are two methods by which chemical peels remove the outer layers of skin:

  • Keratolysis is where an acid penetrates thru the stratum corneum, disrupting cellular connections (the "skin glue" or "skin cement") by breaking the bonds. Examples of these acids include:

  1. Glycolic

  2. Lactic

  3. Salicylic

  • Keratocoagulant is when a chemical agent actually coagulates the protein known as keratin causing it to denature, meaning change. Essentially, the acid is cooking the skin cells but not thermally (heat). Even though the burn from TCA feels thermal, it is actually a chemical change. An example I use when explaining this phenomenon is when you cook an egg white; the protein changes from clear to white. This egg illustration is actually caused by heat changing the protein, not a chemical. If you are familiar with making Ceviche from Latin America, this dish actually illustrates keratocoagulant best. In Ceviche acid is added to fish, it denatures the fish's protein, making it safe to eat without needing to add heat. Example:

  1. TCA


Different acids penetrate the stratum corneum (top layer of skin), disrupting the corneocyte adhesion by dissolving the desmosomal bonds, basically the glue keeping skin together. The deeper the acid can penetrate, breaking these desmosome bonds the more aggressive and higher risk the acid peel becomes.




The majority of chemical peels performed, especially many DIY at home will reside in the mid to upper epidermis. The depth at which any acid will go is based on the following:

  1. Chosen Acid

  2. Percentage Strength

  3. pH of Acid

  4. Time applied

  5. Application technique (applying pressure and rubbing vs light swab)

  6. Quantity of layers applied

  7. Skin preparation (Mechanical removal of top skin via microdermabrasion or dermaplaning; topicals such as lower strength acids and Retinoids)

  8. Skin type (Very oily and thick versus dry and thinned out skin)


ALPHA-HYDROXY ACID'S

Alpha-Hydroxy Acids are commonly referred to as AHA's.


DIFFERENT AHA MOLECULAR STRUCTURES


GLYCOLIC

  • Glycolic Acid – Made from SUGAR CANE, is probably the most popular AHA. It is fantastic for exfoliating and, since it also boasts antimicrobial properties, could help with acne breakouts too. (It won’t clear out the oil from deep within the pores in the same way as BHA, namely Salicylic). Glycolic has long been considered by many professionals to be the best performing acid. As the smallest hydroxyl acid molecule, glycolic acid can penetrate the skin, the deepest and the fastest.

  • Glycolic acid needs to be neutralized, this can be as simple as rinsing it off which will change the pH by diluting, or if it is a very high concentration then a basic solution to actually neutralize the acidic pH.

TAKE AWAY: Glycolic Acid is an AHA

Comes from Sugar

Smallest Molecule

Penetrates the fastest & deepest

Best for tightening skin & collagen stimulation

Must be NEUTRALIZED

LACTIC

  • Lactic Acid – derived from the lactose that is found in MILK. Lactic acid is known for its exfoliating and anti-aging benefits. Like all AHAs, lactic acid is great for general exfoliation and skin brightening. But because this is a larger molecule, the lactic acid does not penetrate as deeply into the skin’s surface as glycolic acid, causing it to be gentler and further, making this the AHA of choice for those with sensitive skin and darker pigmentation.

LACTIC PEEL VIDEO


TAKE AWAY: Lactic Acid is an AHA

Comes from Milk

Larger Molecule

Does not Penetrate as deeply

Hydrates upper levels of skin

Best for all skin types

Does not require Neutralization




MANDELIC

  • Mandelic Acid – made from ALMONDS. Mandelic acid is a highly effective, multitasking acid that helps address fine lines, firmness, acne, and discoloration. Because mandelic is a slightly larger molecule, it’s better for sensitive skin types and for skin types with higher concentrations of melanin because it doesn’t trigger post-inflammatory responses or pigmentation like we see from other AHAs. Due to Mandelic's antimicrobial properties, it’s effective against acne and clogged pores, similar to Salicylic.

  • A study compared a mandelic-salicylic acid combination peel with a glycolic peel, the combined mandelic-salicylic peel saw better overall results and had fewer side effects.

TAKE AWAY: Mandelic Acid is an AHA

Comes from Almonds

Larger Molecule

Does not Penetrate as deeply

Good for darker skin tones & sensitive skin

Mandelic acts similar to Salicilic

Does not require Neutralization

MANDELIC PEEL VIDEO



The mandalic peel is super gentle. I actually used this on Amazon Live and didn't even feel a tingle. You can watch the Mandelic Acid Peel Live HERE






MORE AHA's

There are additional AHAs; below are a few more, however, the others are not used alone in a chemical peel. Instead, they are combined into mixed acid peels with other AHA's or into popular daily skincare exfoliants, such as peel pads and glycolic toners. Further, there are additional mild AHAs that are combined into skincare products but I am not listing all of them.


  • Tartaric Acid – Generated from GRAPE extracts. Tartaric acid is not quite as common as glycolic and lactic but has a few distinct advantages. It is great for tackling acne breakouts and blemishes, while also minimizing the visible signs of sun damage.

  • But its primary benefit is its ability to regulate a formula's pH level, preventing skin irritation and stabilizing solutions, which is why it is paired often in Glycolic and Lactic acid skin serums. An example, of a balanced combination for brightening your skin, is this Dark Spot Corrector.


  • Citric Acid – as you can guess from its name, citric acid comes from CITRUS FRUITS. This AHA is fantastic at neutralizing the skin’s pH level, therefore preventing a whole host of skin issues from arising. Citric acid is also effective at evening out roughness and skin tone. An example is this Vitamin C Complex it has a mix of different citrus fruit acids plus citric acid.


  • Malic Acid – Derived from APPLES. Malic acid isn’t a very effective exfoliant when used on its own. However, it does a great job of increasing the effects of other AHAs when it has been combined with them. An example is this Glycolic Acid Serum that is enhanced with Malic acid.



BETA-HYDROXY ACID'S

Beta-Hydroxy Acids are commonly referred to as BHA'S.


SALICYLIC


30% Salicylic Peel At Home Natural Kaos

  • Salicyclic Acid - Comes from, WILLOW BARK, Wintergreen Oil & Sweet Birch. Salicylic acid is a type of phenolic acid with a chemical formula of C7H6O3. This acid is a BHA and 30% concentration is used for superficial peels. The acidic nature of salicylic acid makes it a good exfoliator with a powerful defense mechanism of your skin against bacteria (Propionibacterium acnes) that cannot survive in extremely acidic environments. It is also an effective treatment for warts caused by Human Papilloma Virus. It acts by breaking the small attachments joining your skin cells together (these are the desmosome bonds discussed earlier), thereby encouraging exfoliation (skin peeling) and unclogging of pores.

  • Salicylic acid has a lipid structure, meaning it can penetrate other lipids, like oil in your pores. This causes salicylic to seek out oily parts of the skin, such as pores, resulting in deep pore cleansing.

  • It should be noted, that while salicylic acid is proven effective against some acne, it does have its limitations. While BHA has been shown to be mildly antibacterial, it has not been shown to kill p. acnes bacteria, the most common bacteria that leads to acne. For this reason, salicylic acid is often paired with antibacterial ingredients or benzoyl peroxide for the best results. Salicylic acid can also be mildly drying to the skin, so it’s important to moisturize when using it.

  • Dermatologists recommend a salicylic acid formulation that contains 0.5% up to 2%(This added information is not for a SA peel but for insight on using SA in your daily protocol).

TAKE AWAY: Salicylic Acid is a BHA

Comes from Willow Bark

Lipid Structure

Can penetrate oily pores

Acne Control

Good for darker skin tones & sensitive skin

30% SA is a superficial peel concentration

Does not require Neutralization


20% Salicylic Acid

30% Salicylic Acid



TRICHLOROACETIC ACID (TCA)

Trichloroacetic acid (TCA; TCAA; also known as trichloroethanoic acid) is an analog of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms. Salts and esters of trichloroacetic acid are called trichloroacetates.

TCA 25% Natural Kaos
  • TCA is synthetically made from acetic acid and chlorine. TCA is the most potent acid peel I do at home and I've had great results using this acid. TCA is different from Hydroxy Acids as it does not break desmosome bonds to shed skin but instead chemically changes the nature of the protein Keratin, thru the process of Keratocoagulant, described above. TCA is also man-made whereas Hydroxy Acids are found naturally.

  • 20% TCA concentration is typically used for superficial peels. I previously obtained TCA acid from Amazon however, in the fall of 2020 Amazon stopped carrying TCA peels. I now find TCA concentrations on eBay.

TCA 30% + 5% Salicylic

TCA 25%

TCA 25% + 5% Salicylic

TCA 15%

TCA 10%

  • As previously explained, TCA peels the skin via the keratocoagulant process. This process is observed by the "frosting" of the skin.

  • As you apply TCA acid it can cause a whiteness in the skin. This cannot be wiped off, the discoloration or denaturing of the protein is observed and is called "frosting". After 30-60 minutes following application, the white will fade to a red sunburn.

  • Unlike glycolic acid, TCA does not need to be neutralized, however, once the depth of the peel is reached and illustrated by the white frost it can be stopped by diluting with water. This is not neutralizing the acid but rather diluting its strength which causes it to stop denaturing the keratin protein.

  • Lighter skin tones are best for TCA as opposed to darker skin that has more melanin and could result in hyperpigmentation spots.

  • TCA can be extremely painful as compared to other acid peels. 20% and 25% strengths can feel like a fire torch on your face.

  • TCA is ideal at:

  1. Removing freckles & Sunspots

  2. Evening out skin tone

  3. Improving texture

  4. Tightening Pores

  5. Reducing Fine Lines


TAKE AWAY: TCA is a man made acid

20% or lower is a superficial peel

Keratocoagulant