BUTTER-C
Signature ingredients
Rosemary scalp serum OEM/ODM manufacturing
Rosemary Scalp Serum · Rosemary Oil Scalp Essence · OEM/ODM
Rosemary is an herb frequently mentioned in scalp care on international markets, usually alongside the rumor that it "grows hair like minoxidil". That rumor comes from a single trial in 100 people with androgenetic (hereditary) hair loss comparing rosemary oil with minoxidil 2% — a drug substance banned in cosmetics — with no placebo group and no replication found so far. A properly made rosemary scalp serum therefore promises neither hair growth nor reduced hair loss: the named ingredient is rosemary essential oil (INCI: Rosmarinus Officinalis Leaf Oil), which brings an herbal scent and a light cooling feel to the scalp, in a clear, fast-absorbing, non-greasy base. The technical work lies elsewhere: the oil does not dissolve in water, its chemotype varies with origin, and the maximum level in a leave-on scalp product is usually set by the impurity methyleugenol — calculated from each batch's certificate of analysis. Butter-C offers full-service OEM/ODM manufacturing, from formulation and testing to labeled finished goods and the notification dossier.
Formula base
Rosemary oil in a clear, fast-absorbing base
The serum is applied to the scalp and left on, not rinsed. The base must be clear, dry quickly and keep hair from looking greasy; the essential oil is added at fragrance level.
Rosemary oil — the right INCI and chemotype
Steam-distilled oil from the flowering tops and leaves, INCI Rosmarinus Officinalis Leaf Oil. The material is in Butter-C's existing ingredient list; the label and notification dossier use the INCI on the certificate of analysis (COA). The European Medicines Agency (EMA) assessment report, citing the European Pharmacopoeia, describes three chemotypes: 1,8-cineole (Morocco, Tunisia), camphor–borneol (Spain) and α-pinene–verbenone (France) — scent and camphor content differ, so each batch COA must state the chemotype and methyleugenol.
Essential oil is not leaf extract
Rosemary leaf extract (Rosmarinus Officinalis Leaf Extract) is a separate INCI: the oil-soluble form, rich in carnosic acid, protects oil phases from rancidity; the water-soluble form contains rosmarinic acid. Data for the two materials are not interchangeable; if both are used, the label lists both INCI names.
Water–glycol base, with or without alcohol
Water, Butylene Glycol or Propanediol hold moisture and help dissolve the oil; a quick-dry version adds a moderate amount of alcohol (Alcohol). No heavy oils or film-forming silicones, so hair does not look greasy.
Solubilizer for the essential oil
The oil is practically insoluble in water: premix it with a nonionic solubilizer (PEG-40 Hydrogenated Castor Oil, Polysorbate 20) until clear, then add it to the water phase. Panthenol and Glycerin can be added for a moisturized scalp feel.
Key technical points
Methyleugenol, clarity, oxidation and cumulative exposure
These four points are where a rosemary serum differs from an ordinary scalp serum; each is settled with the raw-material COA and tests on samples.
Methyleugenol sets the maximum level
ASEAN Annex II (Ref 451) allows methyleugenol only at the natural level of essential oils, with a leave-on finished product at no more than 0.0002%. Maximum oil level (%) = 0.0002 ÷ % methyleugenol on the COA × 100: a COA showing 0.1% allows up to 0.2% oil; a sample with the 5.46% methyleugenol once recorded by CIR allows only about 0.0037%. Butter-C therefore fixes the oil level only after receiving the batch COA.
Clarity and separation
The solubilizer-to-oil ratio is screened in the actual base (usually starting from 1:1 to 5:1 or higher — formulation practice); a new oil batch, added fragrance or a change in alcohol level all require re-testing clarity at low temperature and at 40°C.
Essential oils oxidize easily
Terpenes in the oil oxidize over time, and oxidized oil raises the risk of sensitization. The IFRA standard for limonene sets a peroxide value below 20 mmol/L, for example with 0.1% BHT or tocopherol. In practice: store the oil sealed and away from light, add it during the cool-down phase, and fill the finished product in dark bottles.
Cumulative exposure and penetration
Camphor, limonene and methyleugenol from the oil, fragrance and other extracts in the formula are counted together. CIR notes that rosemary oil increases skin penetration of other substances; in mice, 0.5–1% oil increased the effect of a topical gel. The safety assessment therefore covers the whole formula, not single ingredients.
Three formulation directions
Three types of rosemary scalp serum
Alcohol-free water-based serum
Water, glycol, Panthenol, oil solubilized with PEG-40 Hydrogenated Castor Oil; gentle for daily use, suited to dry or easily stinging scalps.
Quick-dry serum with alcohol, lightly cooling
A water–alcohol base for a quick-dry, fresh feel, optionally with a low level of Menthol. High alcohol levels dry the scalp; total menthol and other potential sensitizers from all sources are added up.
Very light gel serum
A small amount of Hydroxyethylcellulose keeps the serum from running onto the forehead and nape; it stays clear and leaves no film on hair.
Packaging is designed with the formula
Dark glass or plastic bottles with a dropper or comb-tip dropper that delivers the serum straight to the scalp. Essential oils and alcohol can soften or swell some plastics and gaskets — compatibility is tested before sign-off.
Parameters we monitor
What our R&D team measures on every sample
Below are the parameters Butter-C tracks during formulation and scale-up. Specific limits are agreed with you on the approved sample and then written into the product's in-house specification.
- Incoming essential oil COA
- Chemotype, main constituents (1,8-cineole, camphor, α-pinene), methyleugenol, peroxide value — for every batch.
- Methyleugenol in the finished product
- Calculated from the oil level and COA, including any contribution from other fragrance; kept below 0.0002% (Annex II Ref 451, leave-on).
- Clarity and color
- No haze or separation after cold storage and at 40°C; color compared with the reference sample.
- Odor
- Compared with the reference sample after storage; watch for odor changes from oil oxidation.
- pH
- Measured at 25°C; within the range agreed for the scalp and the preservative system.
- Microbiology and preservative challenge test
- Tested at a GLP / ISO 17025-accredited laboratory; preservative efficacy test to ISO 11930 for this water-rich base.
- Irritation assessment (recommended)
- Testing on human volunteers at an independent facility, since the product stays on the scalp daily and contains essential oil.
- Packaging compatibility
- Monitor dropper leakage and plastics or gaskets softened or swollen by oil and alcohol.
Claims
Claims for a scalp serum with rosemary oil
The frequently cited study (Panahi et al., 2015) randomized 100 people with androgenetic hair loss to rosemary oil or minoxidil 2% for 6 months: at month 3 neither group showed a significant change in hair count; at month 6 both groups increased from baseline, with no significant difference between groups; scalp itching increased in both groups. The abstract does not state the oil concentration or base; there was no placebo group; "no significant difference" does not mean "equivalent". This is a medical context and minoxidil is a drug banned in cosmetics (Annex II Ref 372), so the result cannot support a cosmetic claim. Appendix 03-MP (Circular 06/2011/TT-BYT) does not accept "Stimulates hair growth", "Prevents hair loss", "Thickens the hair shaft" or "Restores hair cells/follicles" for hair products.
Herbal scent, contains rosemary oil
Instead of: promises of hair growth or less hair loss, "works like minoxidil", citing studies in people with hereditary hair loss.
Light, refreshing cooling feel on the scalp (sensory evaluation on the finished product)
Instead of: boosts blood flow to nourish follicles, acts on hair follicles.
Cares for the scalp, keeps it comfortable, absorbs fast without greasiness
Instead of: claims about red, itchy or flaking scalp conditions (these need a dermatologist).
Helps hair look fuller — only when measured on the finished product, as a claim for the whole product
Instead of: thickens the hair shaft, restores follicles, grows new baby hair.
Hair color
A self-reported survey on rosemary and gray hair does not allow conclusions either way. Instead of: prevents gray hair, darkens hair.
Label directions (practice)
Avoid the eyes; do not use on broken or irritated scalp; stop if redness or itching occurs; people allergic to rosemary or the mint family should not use it. Heavy, prolonged or patchy hair loss should be examined by a dermatologist.
Manufacturing specifications
Available capabilities
- Texture
- Clear solution, very light gel; with or without alcohol.
- Rosemary material
- Rosemary oil is in Butter-C's existing ingredient list; the level is set from each batch COA.
- Format
- Dropper bottle, comb-tip dropper bottle. Fill volume agreed when packaging is selected.
- Minimum order quantity
- Agreed per order.
- Testing
- Performed at a GLP / ISO 17025-accredited laboratory; certificates of analysis delivered with every batch.
- Documentation
- Product Information File (PIF) and cosmetic product notification dossier prepared by Butter-C, with the oil COA and the methyleugenol calculation.
- Packaging
- Label design, printing and packing run in parallel with formulation.
Suggested product concept
Alcohol-free, lightly cooling rosemary scalp serum
A product concept to help you visualize the line — not a ready-made product for sale. The actual formula is built around your brand's positioning and price point.
Rosemary oil at fragrance level
Level calculated from the COA to keep finished-product methyleugenol below 0.0002%; chemotype chosen for the scent your brand wants.
Clear water–glycol base
Butylene Glycol, Panthenol, Glycerin; oil premixed with PEG-40 Hydrogenated Castor Oil.
Preservation and antioxidant
Preservative system challenge-tested to ISO 11930; Tocopherol with the oil, Disodium EDTA; dark bottle.
60 ml comb-tip bottle
The comb-tip dropper delivers the serum straight to the scalp and limits run-off toward the eyes.
Customization options
What you can specify
The same product type can target very different customers. Tell us your requirements in the areas below and our pharmacists will build the formula to match.
Rosemary scent
Cool 1,8-cineole type, warmer camphor type, or blended with fragrance; chosen on scent samples.
Feel
Gentle alcohol-free, quick-dry with alcohol, with or without Menthol.
Companion ingredients
Panthenol, glycerin, or paired with caffeine as a scalp line — each ingredient has its own claim limits.
Market
Products for the EU must name the fragrance allergens present in the oil (camphor, pinene, limonene, linalool…) above 0.001% in leave-on products under Regulation (EU) 2023/1545; ASEAN and Vietnam have no separate threshold list.
Target users
Adults, normal or oily scalp; not positioned for young children. Pregnancy and breastfeeding: data are insufficient, advise asking a doctor.
Product set
Shampoo and scalp serum in one rosemary line; the oil level in rinse-off shampoo is calculated separately (methyleugenol up to 0.001%).
Further reading
Related topics
Rosemary essential oil in cosmetics
Three chemotypes, the facts behind the minoxidil comparison, methyleugenol and fragrance allergens (in Vietnamese).
Scalp essence manufacturing
The general page on bases, actives and packaging for scalp serums; this page focuses on rosemary oil.
Hair loss vs hair breakage
The hair cycle, what cosmetics can and cannot do, hair claims under Appendix 03-MP and when to see a doctor (in Vietnamese).
Rosemary leaf extract in cosmetics
How it differs from the oil, protecting oil phases from rancidity, and the evidence on skin and hair (in Vietnamese).
Caffeine scalp serum manufacturing
A scalp line named for caffeine — different active, solubility and claim limits.
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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