A double-layer cream-in-serum is one of the most requested formats in OEM skincare briefs, yet many buyers are unsure what actually keeps the two phases stable in one bottle. This guide breaks down the formulation decisions behind the OEM Deep Collagen Anti-Wrinkle Face Serum (model PS21-SP) from Lanthome — active selection, pH targets, emulsifier strategy, preservatives and stability testing — so you can brief a manufacturer with confidence. The short version: a stable two-phase serum depends less on exotic ingredients than on disciplined pH control, a well-matched emulsifier system and a preservative plan built for a water-rich formula.
Key takeaway: the cream-in-serum format combines a lightweight serum phase with a richer cream phase in a single bottle, and its viability rests on three formulation pillars — active compatibility, pH design and stability verification. Each pillar can be customized for your brand under Lanthome's OEM/ODM service, with sample orders available for evaluation before full production.
The cream-in-serum format is exactly what the name suggests: one bottle that holds two distinct layers — a fluid serum phase and a richer cream phase — rather than a single homogeneous lotion. In use, the product is shaken so the layers blend into a temporary emulsion that delivers both the light feel of a serum and the cushioning texture of a cream. This is a cosmetic format choice designed for sensory experience and daily care convenience; it does not imply any medical or treatment function.
For brand owners, the format is attractive because it creates visible product differentiation on the shelf. The Lanthome Deep Collagen Anti-Wrinkle Face Serum is positioned as a facial care product for home use, listing collagen, vitamin E and peptides as main ingredients, with vitamin C, hyaluronic acid and herbal actives in the ingredient statement. It is a liquid-form face product offered in five sizes — 15ml, 30ml, 50ml, 90ml and 100ml — in a rice white color, with a 3-year shelf life stated on the product page.
From a formulation standpoint, two-phase formats raise questions that single-phase serums never do: how do the phases stay visually separated on the shelf, how do they mix on shaking, and how does the formula remain microbiologically safe across the stated shelf life? The sections below answer each question in turn.
Active selection in a cream-in-serum starts with deciding which ingredients live in which phase. The serum layer usually carries water-soluble actives and humectants, while the cream layer carries oils, emollients and lipid-soluble actives. For the Lanthome deep collagen serum, the page lists collagen, vitamin E and peptide as main ingredients, supported by vitamin C, hyaluronic acid and herbal extracts.
| Active | Typical Role in Cosmetic Formulation | Solubility / Phase Preference |
|---|---|---|
| Collagen | Film-forming and hydration support; commonly used in skin conditioning cosmetics | Water-dispersible; serum or cream layer |
| Peptides | Skin-conditioning agents often used in anti-aging positioning | Water-soluble; serum layer |
| Vitamin E (tocopherol) | Antioxidant support and emollient | Oil-soluble; cream layer |
| Vitamin C | Antioxidant support; stability is pH- and packaging-sensitive | Water-soluble; serum layer |
| Hyaluronic acid | Humectant for hydration support | Water-soluble; serum layer |
Two formulation notes are worth raising with any supplier. First, collagen in cosmetics functions as a film-forming and moisturizing ingredient — it is not the same molecule as skin collagen, and cosmetic use is subject to formulation and testing. Second, pairing vitamin C with vitamin E is a common antioxidant strategy in skincare literature, since the two actives support each other differently depending on the delivery system; the actual synergy depends on concentration, pH and packaging, which the Cosmetic Ingredient Review has reviewed across many individual ingredients.
A practical buyer question to ask during sampling: which actives are in the serum layer and which are in the cream layer, and how does the separation behavior change if you request a different active mix? Because this product is offered under OEM/ODM private label service with formula customization, the active split is a negotiable design variable rather than a fixed spec.
pH is the single most consequential number in a two-layer formula, because it affects active stability, preservative performance and skin compatibility at the same time. Most facial serum formulas are designed in the pH 4.5–6.5 range, a window that balances the skin's naturally acidic surface with the stability needs of common preservatives and actives.
Three pH-related checks should be part of any buyer-supplier discussion:
The European Commission's cosmetics regulatory framework (Regulation (EC) No 1223/2009) requires that cosmetic products be safe when used under normal conditions, and pH is part of the technical dossier a responsible manufacturer keeps for each formula. When you request samples, ask for the product's pH range and how it is controlled during production — this is a routine question that separates experienced OEM partners from generalists.
The cream layer is the structural heart of a two-phase product. To remain stable, it needs an emulsifier system matched to its oil content, and a viscosity profile that keeps the two layers visually distinct without over-thickening either phase.
Emulsifier selection typically follows a few established patterns:
The goal is a product that separates cleanly when at rest, blends easily when shaken, and re-separates at a predictable rate — all properties that are verified through stability testing rather than assumed from the formula sheet. Good manufacturing practice, such as that described in ISO 22716, covers the production hygiene and batch consistency that keep these properties identical from batch to batch.
Water is the part of any formula that needs the most microbiological attention. A cream-in-serum contains a significant water phase in both layers, which means the preservative system does real work across the product's shelf life — in the factory, in transit and in the consumer's bathroom.
Preservatives used in cosmetics are regulated at ingredient level; in the EU, for example, the permitted list and concentration limits sit in Annex V of Regulation (EC) No 1223/2009, and the U.S. FDA cosmetics program sets out labeling and safety expectations for marketed products. Three points matter for brand buyers:
The Lanthome serum page lists a 3-year shelf life, which implies the finished product was assessed for stability and preservation over that horizon. When you evaluate samples, request the preservative system summary and challenge-test status as part of your technical due diligence.
Stability testing is where two-phase formats either pass or fail. Because the product has two physically distinct layers, it faces everything a single-phase serum faces — plus separation, creaming and re-mixability issues unique to the format. A professional supplier verifies the following as standard practice:
| Test | What It Checks | Why It Matters for Two-Phase Formulas |
|---|---|---|
| Heat–cold cycling | Behavior under temperature swings | Layer separation and viscosity shifts |
| Centrifugation | Accelerated separation resistance | Whether the cream layer holds under stress |
| Long-term storage | Real-time stability at defined conditions | Confirms the stated shelf life |
| Light exposure | Photosensitivity of actives and color | Guards antioxidants and appearance |
| Challenge test | Preservative effectiveness | Microbiological safety over shelf life |
For the deep collagen serum, the stated 3-year shelf life and available MSDS documentation indicate that the product was assessed through the manufacturer's standard stability and safety procedures. Buyers should still request the specific stability data for their customized version: any change to actives, fragrance, color or packaging can shift stability outcomes, which is why the FDA and EU frameworks both place product-safety responsibility on the responsible person for the marketed product.
A practical sampling tip: test the two-phase behavior yourself. Shake the sample, note how quickly and completely it re-separates, and store one unit in a warm environment and one in a cool environment for two weeks. Visual separation behavior is one of the easiest quality signals a non-chemist can evaluate before committing to an order.
For private label buyers, the formulation discussion only becomes useful when it connects to what can actually be customized. The Lanthome serum's product page gives a concrete customization map:
This specificity is exactly what you want from an OEM partner: known sizes, known MOQ tiers and known documentation. The Serum collection on Lanthome's site shows how the same manufacturing base serves a wide range of serum formats, which is a useful benchmark when comparing suppliers.
The documents behind a product matter as much as the formula. For a private label serum, the standard documentation set includes a Certificate of Analysis (COA) per batch, Material Safety Data Sheet (MSDS) for logistics and compliance, and GMP-aligned production records. The Lanthome page lists ISO22716/GMP, BSCI, SGS, Intertek and CE among its stated certifications and testing capabilities, and states that samples are available before ordering.
Payment terms for this supplier include T/T, PayPal, Western Union, bank transfer and Alibaba Trade Assurance, which gives buyers flexibility across regions and order sizes. Combined with the stated factory location in Guangzhou (near the airport) and an export-licensed manufacturer model, the practical sourcing picture is: samples first, document verification second, then a production order with defined MOQ and lead time.
If you are comparing multiple suppliers, ask each for the same four items — batch COA, challenge-test summary, stability summary and GMP evidence — and compare them side by side. This converts a marketing conversation into a technical one, and it is the fastest way to identify which partner can actually deliver a stable two-phase serum at scale.
What is a cream-in-serum (double-layer) formula?
It is a cosmetic format where a serum layer and a cream layer sit in one bottle and are blended by shaking before use. It is a texture and experience choice for daily facial care, not a medical treatment claim.
Is a double-layer serum more difficult to stabilize than a normal serum?
Yes, generally speaking. Two-phase formats face separation and re-mixability challenges on top of the usual active-stability and preservation work. Stability testing — heat–cold cycling, centrifugation and long-term storage — is essential.
What pH should a collagen face serum target?
Most facial serum formulas are designed in the pH 4.5–6.5 range to balance active stability, preservative efficacy and skin compatibility. Your supplier should state the formula pH and its control range in production.
Can I customize the actives, color and size of this serum?
Yes. The Lanthome deep collagen serum is offered under OEM/ODM private label service with five size options (15ml–100ml), rice white as the reference color, and custom color and formula development on request.
What is the MOQ for this product?
Sample MOQ is 1 piece; in-stock MOQ is 100 pieces; custom production MOQ is 500–1000 pieces; special-process MOQ is 3000 pieces. Contact the Lanthome team for a quote on your specific specification.
What documentation should I request before ordering?
Request a batch Certificate of Analysis (COA), preservative challenge-test summary, stability summary and GMP evidence. The supplier states ISO22716/GMP, BSCI, SGS, Intertek, CE, COA and MSDS among its documentation.
About the Author
This article was prepared by the Lanthome skincare manufacturing team, with experience in private label formulation, packaging development, quality control, and international OEM/ODM projects.
