BUTTER-C
Signature ingredients
Mandelic acid serum OEM/ODM manufacturing
Mandelic Acid Serum · Signature Ingredients · OEM/ODM
Mandelic acid (2-hydroxy-2-phenylacetic acid) is an alpha-hydroxy acid (AHA) with an aromatic ring: molecular weight 152.15, twice that of glycolic acid (76.05), and less water-loving (XLogP 0.6 versus −1.1 according to PubChem). That is why it is often presented as a “gentler” AHA for oily, breakout-prone and sensitive skin. The basis for this is thin: one comparative study in people, measured by reflectance spectrophotometry, found that 10% glycolic acid exfoliated faster and caused more redness and photosensitivity than mandelic acid (Rizza et al., 2010) — the abstract gives neither the sample size nor the mandelic acid concentration. Most of the other data come from 30–45% peels performed by doctors in clinics, outside the scope of home-use cosmetics. Legally, mandelic acid is not listed in ASEAN Annexes II, III or VI and does not fall under entry A6 (glycolic and lactic acid only): there is no specific limit, but the manufacturer must establish concentration and pH through a safety assessment, irritation testing and stability testing. A Butter-C mandelic acid serum therefore starts from three decisions — concentration, pH and an acid-tolerant base — tested on the finished product itself, with claims at the level of gentle exfoliation for a smoother skin surface, plus sun-care advice. Butter-C offers full-service OEM/ODM manufacturing, from formula development to labeled finished product with its notification dossier.
Formula base
Mandelic acid is the axis; base and pH are arranged around it
Unlike the acne serum page (salicylic acid and niacinamide as the axis), this page puts an AHA with no specific limit at the center — so every choice of concentration, pH and base has to be justified in the safety file.
Mandelic acid — the signature ingredient
INCI Mandelic Acid; the raw material on file at Butter-C is DL-mandelic acid, a white crystalline powder (CAS 90-64-2 for dl-mandelic acid per PubChem). The COA should state purity, isomer form and impurities; pKa and solubility come from the supplier's TDS — Butter-C's verified sources have no readable pKa or solubility figures, so this page states none. Percentages in the formula are calculated as the free acid.
Solvents and neutralizer
Water with Butylene Glycol or Propanediol to aid dissolution: mandelic acid is less water-loving than glycolic acid, so solubility and crystallization at the target concentration need checking, especially in cold storage. Sodium Hydroxide partially neutralizes the acid to reach the target pH; neutralization lowers the free-acid fraction, but the percentage on the label remains the total calculated as the acid.
Acid-tolerant humectant base
Glycerin, Betaine and Butylene Glycol reduce the feeling of tightness. Panthenol and Allantoin are stable from pH 4 upward according to the ingredient monographs (as on the AHA toner page) — added only when finished-product pH is set at 4 or above and monitored through stability testing. No fragrance, no retinoid in the same bottle.
Thickening and preservation at low pH
Standard carbomer loses viscosity at low pH (the raw material record lists this incompatibility too) — use Hydroxyethylcellulose, Xanthan Gum or Sclerotium Gum. Preserve with Phenoxyethanol (max. 1.0% — Annex VI Ref 29) plus Ethylhexylglycerin, or Sodium Benzoate (leave-on max. 0.5% calculated as benzoic acid — Annex VI Ref 1), whose efficacy depends on pH; low pH does not replace the preservative challenge test. Disodium EDTA helps keep the color.
Key technical points
Four points to settle before discussing skin feel
Two serums both labeled “mandelic acid” can act very differently on skin depending on concentration, pH and base. With no legal ceiling to lean on, the four items below are the main work of the file.
No specific limit does not mean anything goes
Mandelic acid is not listed in Annexes II, III or VI (version 2026-1). Entry A6 of Annex III covers only “Glycolic and lactic acid, their common salts and simple esters” — not mandelic acid, so there is no specific concentration limit or mandatory label text. In exchange, the Product Information File (PIF) must contain a safety assessment for the exact concentration and pH chosen; no CIR or SCCS assessment specific to mandelic acid was found. The A6 levels (skin products for general use ≤ 10% calculated as the acids, pH ≥ 3.5) can serve as a cautious reference — that is the manufacturer's choice, not a legal basis for mandelic acid.
Concentration and pH fixed on the finished product
Verified sources have no reliable data on mandelic acid concentration ranges in retail products; the 30–45% levels in studies are all peels. The topical facial trial found (Jacobs and Culbertson, 2018: 24 people, twice daily, 4 weeks, no control group) has an abstract that does not state the concentration. Butter-C starts testing at a low level, around 2–5%, pH around 3.5–4.5 — formulation experience, to be tested on the finished product — then fixes it through stinging, irritation and stability tests. The free-acid fraction falls as pH rises; the exact calculation uses the pKa on the TDS.
Dissolution, crystallization and color
XLogP 0.6 (PubChem): less water-loving than glycolic acid (−1.1) and lactic acid (−0.7) — without enough co-solvent it crystallizes easily in the cold, so samples are always held at 4 °C for observation. Verified sources have no data on light or oxygen sensitivity; the internal raw material record notes that solutions may yellow on prolonged light exposure (not independently verified) — Butter-C runs light-exposure tests in the final packaging and favors light-protective bottles.
Combining with other acids and actives
Salicylic acid must stay within Annex III Ref 98 (max. 2.0% for facial products, counting all salicylic acid in the formula). Glycolic and lactic acid count toward the A6 total, and from 2.5% (in products without a sunscreen) the sunburn warning under footnote (13) becomes mandatory. Gluconolactone is outside A6 but hydrolyzes to gluconic acid, making pH drift. Retinol and other AHAs add up in irritation — use them at different times, not in the same bottle. Niacinamide is not compatible with acids (general toner page) — not combined by default in a low-pH serum.
Three formulation directions
Three ways to put mandelic acid into a serum
Low-strength single-acid mandelic serum
Light Hydroxyethylcellulose gel, glycerin, betaine; mandelic acid partially neutralized. A short formula that is easy to explain on the label — for oily or combination skin new to AHAs. Claims stop at mild surface smoothing, to be tested on the finished product.
Mandelic acid – PHA serum for easily irritated skin
Add Gluconolactone (around 3–5%: 5% is the serum level tested in people cited on the PHA toner page, 3% is formulation experience); neither acid falls under entry A6. Gluconolactone hydrolyzes, so pH is readjusted once the system has equilibrated and is monitored through stability testing. The word “gentle” goes on the label only after stinging and tolerance tests on the finished product itself.
Mandelic – salicylic serum for oily, breakout-prone skin
Salicylic acid max. 2.0% (Annex III Ref 98), predissolved in glycol; HPLC assay on every batch. The sentence “Not to be used for children under three years of age” is mandatory for products that might be used for children under three (footnote (8)); an adult serum may carry it as a voluntary note, as on the BHA toner page. This is not the clinic peel combining 20% salicylic acid + 10% mandelic acid — no peel-like results are promised.
Packaging is designed together with the formula
Dark glass bottle with an acid-resistant dropper gasket, or an acid-resistant plastic pump bottle; avoid metal parts that are not acid-resistant. Bottle, gasket and dropper are soak-tested with the sample in the stability study, not afterwards.
Parameters we monitor
What our R&D lab measures on every sample
Below are the parameters Butter-C monitors during formula development and scale-up to production. Specific limits are agreed with you on the approved sample and then written into the product's in-house specification.
- pH
- Measured directly at 25 °C on every batch; the pH range in the in-house specification is fixed from irritation and stability results. pH drift is monitored, especially in the gluconolactone version.
- Acid content
- HPLC assay of mandelic acid (and salicylic acid if present) at the start and after stability testing; A6 total worksheet when glycolic or lactic acid is used.
- Sensory profile, color & clarity
- Color, odor and clarity against a reference standard; yellowing monitored across stability time points, including light-exposed samples.
- Low-temperature crystallization
- Held at 4 °C and through freeze–thaw cycles; watching for mandelic or salicylic acid crystals.
- Viscosity
- Rotational viscometer, spindle and speed recorded; acid-tolerant polymers rechecked after stability testing, matched to dropper or pump.
- Stability
- Accelerated aging at 40 °C, freeze–thaw cycling and light exposure; monitoring pH, acid content, color, clarity and viscosity.
- Packaging compatibility
- Soaked with the exact bottle, gasket and dropper to be used; monitoring gasket swelling, material odor and signs of corrosion.
- Microbiology & preservative challenge
- Tested at a GLP / ISO 17025-accredited laboratory; ISO 11930 preservative efficacy (challenge) test on the final formula.
- Stinging & irritation
- Tested on volunteers, including facial stinging — the basis for fixing concentration and pH and for writing the safety assessment in the PIF.
Claims
Writing claims within the cosmetic scope
Four of the five clinical studies on mandelic acid summarized in the ingredient article are clinic peels in people with acne, melasma or dark circles; a 2020 Cochrane review rated the evidence comparing glycolic peels with salicylic–mandelic peels as low quality. Promotional wording slides easily into that language, while Annex 03-MP of Circular 06/2011/TT-BYT does not accept drug-like claims. Below is the wording Butter-C proposes.
Gently exfoliates, leaves the skin surface smoother
“Gently” only once stinging and irritation have been tested on the finished product. Instead of: peels skin, resurfaces skin, regenerates skin, “at-home peel”, “as effective as a peel”.
Suitable for oily, breakout-prone skin
Describes the skin type. The 45% mandelic acid peel (Dayal et al., 2020: 50 people, randomized, versus a 30% salicylic acid peel, no significant difference in acne score) and the 20% salicylic + 10% mandelic peel (Garg et al., 2009: 44 people) are medical procedures and do not become product benefits. Instead of: drug-like claims about acne, claims to act on bacteria, clears acne.
Contains mandelic acid (AHA), with percentage
Percentage stated only when it matches the assay. Instead of: brightens skin, fades dark marks, erases melasma — the pigmentation data are peels in a medical setting (Sarkar 2016: salicylic–mandelic peels after 4 weeks of priming with prescription hydroquinone + tretinoin cream; Malviya 2025: 30% peel around the eyes, outperformed by a 30% lactic acid peel).
Helps skin look smoother and clearer
Describes the perceived result, to be tested on the finished product. Instead of: rejuvenates skin, increases elasticity, firms — the lower-eyelid elasticity study (Jacobs and Culbertson, 2018) had no control group, the authors developed the formula themselves and the abstract does not state the concentration.
Sun-care advice on the label
The U.S. FDA recommends a sun-sensitivity warning for cosmetics containing AHAs in general. The “Sunburn alert” sentence mandated by footnote (13) of Annex III applies only to glycolic and lactic acid — for mandelic acid it is voluntary labeling, and Butter-C recommends always advising daytime sunscreen; if glycolic or lactic acid is added at 2.5% or more, that sentence becomes mandatory. Instead of: “does not cause sun sensitivity”, dropping the sunscreen advice.
Directions and label notes
Use in the evening, start every other day, patch test on a small area first; do not use on broken or irritated skin; use at different times from retinol and other AHAs; stop if redness or burning persists. There is one reported case of allergic contact reaction on the lips to mandelic acid (Aguirre 1994) — avoid the lip area. Pregnancy: not enough data, ask a doctor. Instead of: suitable for every skin type, safe for pregnancy.
Manufacturing specifications
Our capabilities
- Texture
- Clear liquid serum or light gel, colorless to pale yellow.
- Pack formats
- Dark glass bottle with dropper, or acid-resistant plastic pump bottle. Volume agreed when choosing packaging.
- Minimum order quantity
- Agreed per order — depends on the formula direction and pack format chosen.
- Testing
- Performed at a GLP / ISO 17025-accredited laboratory, including acid assay and pH on every batch; certificate of analysis delivered with every batch.
- Documentation
- Product Information File (PIF) and cosmetic product notification dossier prepared by Butter-C, including the safety assessment for the chosen concentration and pH and the irritation test results.
- Packaging
- Label design, printing and packing run in parallel with formula development; the sun-care advice is laid out from the first label draft.
Suggested product concept
Low-strength, fragrance-free mandelic acid gel serum for oily and combination skin
A product concept to help you picture the result, not a ready-made product for sale. The actual formula is developed around your brand's positioning and price range.
Partially neutralized mandelic acid
The signature ingredient; concentration and pH fixed through stinging, irritation and stability tests, starting at a low level based on formulation experience.
Glycerin, Betaine, Butylene Glycol
Humectants and co-solvent alongside the acid; Panthenol added only when finished-product pH is 4 or above.
No fragrance, no alcohol, no retinoid
A short ingredient list so mandelic acid is the main character and tolerance is easy to assess.
30 ml dark glass dropper bottle
Label with directions for evening use, starting every other day, and advice to use sunscreen during the day.
Customization options
What you can specify
The same product type can serve very different customer groups. Tell us your requirements in the areas below and our pharmacists will develop the matching formula.
Concentration and pH
A low level for beginners or a higher one for experienced AHA users — each level means its own round of irritation testing and its own safety assessment in the PIF.
Combined acids
Mandelic acid alone, with gluconolactone, or with salicylic acid — decides pH, the limits that apply and the label wording.
Texture
Water-thin or light gel; dropper or pump.
Humectant group
Glycerin, Betaine, Butylene Glycol, Propanediol, Panthenol, Allantoin — chosen according to finished-product pH.
Fragrance and color
We recommend no fragrance and no color for an acid leave-on facial product.
Ingredient positioning
Alcohol-free, fragrance-free, paraben-free, vegan — please state these at the outset so the right raw materials can be chosen.
Further reading
Related knowledge
Mandelic acid in cosmetics
A large-molecule AHA: mechanism, peel studies, level of evidence, ASEAN rules and cautious use (in Vietnamese).
Acne serum manufacturing
General page for oily, breakout-prone skin with salicylic acid and niacinamide as the axis.
AHA glycolic acid toner manufacturing
An AHA under entry A6: total ≤ 10%, pH ≥ 3.5, mandatory sunburn warning.
PHA gluconolactone toner manufacturing
The non-A6 acid that joins mandelic acid in the version for easily irritated skin.
BHA salicylic acid toner manufacturing
Annex III Ref 98 limits, dissolution and pH of salicylic acid.
UVA, UVB, visible light and the skin
Why AHA users need sun protection while using the product (in Vietnamese).
How we work
From idea to finished batch
Eight steps and three milestones signed off by both sides: approved sample, notification number, finished batch. Step-by-step details (in Vietnamese) →
Get started
Tell us about the product you plan to launch
Send us your product direction and expected volume. Our team will get back to you during business hours (Vietnam time, GMT+7).
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