Why We Use Both Lactic AND Glycolic Acid (Plus: The Korean Secret We Actually Trust)
The honest breakdown of our AHA Exfoliant Toner formulation—and why fermented black tea isn't just trendy BS
Most skincare brands pick a lane: lactic acid or glycolic acid. Not both. Why? Because formulating with two different AHAs requires actually understanding what you're doing. It's easier to slap one acid in a bottle, call it exfoliating, and move on.
We didn't take the easy route.
Our AHA Exfoliant Toner uses 6% lactic acid + 3% glycolic acid, plus fermented black tea. That's not random. That's deliberate formulation based on how these ingredients actually work with your skin. Let's break down why.
The Molecular Size Thing Everyone Gets Wrong
Here's what you need to know: molecular size determines how deep an ingredient penetrates your skin.
Glycolic Acid:
- Smallest AHA molecule
- Penetrates deeper into skin
- Works faster
- More intense exfoliation
- Derived from sugar cane
Lactic Acid:
- Larger AHA molecule
- Stays closer to skin's surface
- Gentler action
- Hydrates while exfoliating
- Originally derived from milk (though modern formulations use vegan fermentation)
Think of it this way: glycolic acid is a scalpel. Lactic acid is sandpaper. Both remove dead skin, but they work at different depths and intensities.
Most brands make you choose between them. We said: why not use both strategically?
The Science: What Actually Happens on Your Skin
Glycolic acid's superpower:
That tiny molecule gets into your pores and between skin cells. It breaks down the "glue" holding dead skin cells together, speeds up cell turnover, and stimulates collagen production in the dermis (the deeper skin layer). Research shows it's particularly effective for hyperpigmentation, fine lines, and textured skin.
A 1996 study compared 5% and 12% lactic acid treatments. The 5% treatment only affected the epidermis (surface layer), while 12% penetrated to the dermis. Glycolic acid, being smaller, can achieve deeper penetration even at lower concentrations.
Lactic acid's advantage:
Bigger molecules mean it works primarily on the skin's surface—which is exactly where most of your visible texture issues live. But here's what makes lactic acid different: it's also a humectant. While it's exfoliating, it's simultaneously pulling moisture into your skin.
This matters because glycolic acid alone can be drying. Lactic acid compensates.
Lactic acid is also part of your skin's Natural Moisturizing Factor (NMF)—components your skin naturally produces to stay hydrated. Using it topically supports your skin barrier instead of just stripping it down.
Why We Chose 6% Lactic + 3% Glycolic (The 9% Strategy)
Total AHA concentration: 9%
Could we have gone higher? Sure. Would it be better? Not necessarily.
Here's our thinking:
6% Lactic Acid:
- Primary exfoliant for surface texture
- Hydration support
- Gentle enough for daily use (once skin is acclimated)
- pH-optimized for effectiveness without excessive irritation
3% Glycolic Acid:
- Deeper penetration for pore clarification
- Collagen stimulation
- Addresses pigmentation at the dermal level
- Lower concentration prevents over-exfoliation when combined with lactic
The ratio isn't arbitrary. We wanted glycolic's deeper action without the harshness that comes with high concentrations. By pairing it with a higher percentage of lactic acid, you get comprehensive exfoliation—surface to mid-depth—with built-in hydration.
Most "gentle" exfoliants only work on the surface. Most "powerful" exfoliants trash your skin barrier. This combination addresses both problems.
The pH Factor (Because It Actually Matters)
AHAs work best at a pH between 3-4. Too high, and they won't exfoliate effectively. Too low, and you're irritating your skin for no reason.
Lactic acid has a pKa (the pH where it's most effective) of 3.8. Our formula sits right in that sweet spot—acidic enough to work, balanced enough not to burn.
This is why some AHA toners sting like hell and others feel like... water. It's all pH.
Enter: Fermented Black Tea (Not Just K-Beauty Hype)
Korean skincare has been using fermented ingredients for centuries. Not because it's trendy—because fermentation actually changes how ingredients function.
What fermentation does:
- Breaks down molecules into smaller sizes → Better skin absorption
- Creates beneficial acids and enzymes → Enhanced bioavailability
- Produces postbiotics → Supports skin microbiome
- Increases antioxidant activity → Research shows fermented tea extracts have higher antioxidant levels than unfermented tea
Why we added it to our AHA toner:
Exfoliating acids can disrupt your skin's microbiome if you're not careful. Your skin hosts trillions of bacteria, fungi, and other microorganisms that protect you from environmental damage, regulate inflammation, and maintain barrier function.
Aggressive exfoliation without microbiome support = potential irritation, sensitivity, increased breakouts.
Fermented black tea (kombucha) contains:
- Probiotics and postbiotics that support beneficial skin bacteria
- Polyphenols (antioxidants from tea) made more bioavailable through fermentation
- Organic acids (lactic, acetic, gluconic) that naturally balance skin pH
- B vitamins that support cellular metabolism
- Ceramides and amino acids created during fermentation
A 2021 study published in Scientific Reports found that kombucha ferments showed strong ability to inhibit enzymes that break down collagen and elastin (lipoxygenase, collagenase, elastase). Inhibition rates hit around 40% after 14-21 days of fermentation.
Another study in Molecules (2024) demonstrated that both green and black tea kombucha had approximately 87% antioxidant activity and high levels of phenolic acids and caffeine that could penetrate and accumulate in skin.
Translation: Fermented black tea doesn't just sound fancy. It actively protects your skin while you're exfoliating it.
The Korean Connection (That's Actually Relevant Here)
Our AHA Exfoliant Toner is made in Korea. That's not a marketing gimmick—it's where fermentation expertise in skincare formulation is most advanced.
Korea has been fermenting food (kimchi, doenjang, makgeolli) for over 2,000 years. That knowledge translated directly into cosmetics. Traditional Korean women used fermented rice water from making makgeolli (rice wine) for skin brightening. Those byproducts became the foundation for modern fermented skincare.
Brands like Missha's Time Revolution line and SU:M37 (named for the optimal fermentation temperature of 37°C) pioneered commercial fermented skincare in the early 2000s. They proved fermentation wasn't just traditional wisdom—it was scientifically measurable improvement in ingredient efficacy.
By manufacturing in Korea, we're tapping into decades of refined fermentation processes and quality control that simply don't exist at the same level elsewhere.
What This Means For Your Skin
You're getting surface exfoliation, deeper cellular turnover, hydration support, microbiome balance, antioxidant protection, and barrier support. All in one product.
You're getting:
- Surface exfoliation (lactic acid) that removes dead cells without stripping
- Deeper cellular turnover (glycolic acid) that addresses texture, pigmentation, pores
- Hydration support (lactic acid's humectant properties)
- Microbiome balance (fermented black tea's probiotics/postbiotics)
- Antioxidant protection (polyphenols from fermented tea)
- Barrier support (amino acids and ceramides from fermentation)
All in one product. No 10-step routine required.
The Stuff We Added That Also Matters
Beyond the acids and fermented tea, we included:
Hyaluronic Acid: Because exfoliating without hydrating is counterproductive. HA pulls moisture into freshly exfoliated skin.
Sacred Lotus Extract: Antioxidant-rich botanical that calms inflammation. Exfoliation can trigger low-level inflammation; lotus helps regulate that response.
Ginger + Rosemary Extracts: Circulation support and additional antioxidant activity. Ginger has anti-inflammatory properties backed by research.
Mushroom Extracts: Adaptogenic compounds that help skin resist stress. Also soothing.
Every ingredient serves a function. Nothing's there for label appeal.
How To Actually Use This
Start slow. Even though this formula is balanced, your skin needs to acclimate to exfoliating acids.
Week 1-2: Use 2-3 times per week
Week 3-4: Increase to every other day if skin tolerates
Ongoing: Daily use is fine for most people once acclimated
Application:
- After cleansing, saturate a cotton pad and sweep over face and neck
- Leave on—do not rinse
- Follow with serum and moisturizer
- The toner can feel slightly tacky due to hyaluronic acid; this is normal
Daytime use: Wear sunscreen. AHAs increase sun sensitivity. This isn't optional.
What to expect:
- Immediately: Skin may tingle slightly (normal). If it burns, remove immediately.
- Week 1: Smoother texture, brighter tone
- Week 4: Reduced pore appearance, more even skin tone
- Week 8+: Improved texture, clarity, visible reduction in fine lines
Who This Is For (And Who Should Skip It)
Use this if:
- You have dull, uneven skin tone
- Texture issues (rough patches, bumps)
- Clogged pores or mild breakouts
- Early signs of aging (fine lines, loss of firmness)
- You want exfoliation without harsh physical scrubs
- Your skin can handle acids (most people, once acclimated)
Skip this if:
- You have active eczema, rosacea, or severely compromised skin barrier
- You're using prescription retinoids (check with dermatologist first)
- You're pregnant or nursing (always consult your doctor)
- You have fungal acne (some people with fungal acne react poorly to fermented ingredients)
If you're unsure, patch test first.
The Honest Truth About AHAs
Chemical exfoliants aren't magic. They're chemistry.
They work when formulated correctly: right pH, right concentrations, right supporting ingredients. They fail when brands prioritize marketing over formulation.
Could you get similar results from a glycolic-only or lactic-only toner? Maybe. But you'd need different products to address what the other acid does better. Or you'd need higher concentrations that might irritate your skin.
Our approach: combine them intelligently, support with fermented ingredients that protect skin barrier and microbiome, formulate at the right pH, skip the unnecessary additives.
The result is exfoliation that actually improves your skin over time instead of just creating a temporary glow that disappears the moment you stop using it.
The Bottom Line
Lactic acid: gentle surface exfoliation + hydration
Glycolic acid: deeper penetration + faster results
Both together: comprehensive exfoliation without compromising skin barrier
Fermented black tea: microbiome support + antioxidant protection + enhanced absorption
This isn't trend-chasing. It's what happens when you prioritize formulation over hype.
Korean skincare didn't get fermentation right by accident. Centuries of food fermentation translated into cosmetic innovation because the science holds up. We're using that expertise—not appropriating it for marketing, but sourcing from where the knowledge lives.
Same logic applies to our acid combination. Two different AHAs working at different depths, balanced for effectiveness without destruction.
Skincare should work. Not just sound impressive.
Sources & Further Reading
On AHAs and skin penetration:
- Tang, S.C., & Yang, J.H. (2018). Dual Effects of Alpha-Hydroxy Acids on the Skin. Molecules, 23(4), 863.
- Kornhauser, A., et al. (2010). Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clinical, Cosmetic and Investigational Dermatology, 3, 135-142.
On fermented ingredients in skincare:
- Żółkiewicz, J., et al. (2024). Kombucha as a Potential Active Ingredient in Cosmetics—An Ex Vivo Skin Permeation Study. Molecules, 29(5), 1018.
- Antolak, H., et al. (2021). Effect of fermentation time on the content of bioactive compounds with cosmetic and dermatological properties in Kombucha Yerba Mate extracts. Scientific Reports, 11, 18792.
On skin microbiome:
- Sfriso, R., et al. (2020). The role of the skin microbiome in skin aging. Journal of Clinical Medicine, 9(10), 3103.
