The Anti Aging Serum Formulation Process, Stage by Stage

Stage one: turning an idea into a formulation brief

Anti ageing is a marketing category, not a technical specification. A laboratory cannot formulate against it. What it can formulate against is a defined mechanism, a defined target user and a defined set of constraints.

A brief that a formulator can work with answers these questions:

• **Which visible concern is primary?** Fine lines, loss of firmness, uneven tone, dullness, or texture. Pick one primary and at most one secondary. A serum that addresses five concerns usually under-delivers on all of them because each active has to be dosed down to coexist.
• **Who is the user?** Age range, skin type, climate, and whether they already use retinoids or acids. A formula for a first-time user in a humid climate looks nothing like one for an experienced user in a dry one.
• **Where does it sit in the routine?** Before moisturiser, under sunscreen, morning or evening. This determines acceptable finish and absorption speed.
• **What price tier and which channel?** This sets the realistic cost of the active system, the packaging budget and the volume per bottle.
• **Which markets?** Regulatory limits on specific ingredients and permitted claim language differ between markets, and that difference can rule an active out entirely.
• **What must be excluded?** Fragrance, essential oils, silicones, alcohol, animal-derived ingredients, specific preservatives.

The last question deserves emphasis because exclusions constrain more than inclusions. A brief that says no alcohol, no silicones, no synthetic fragrance and natural-origin preservation has already eliminated a large part of the formulator's toolkit, and the remaining options will shape texture and shelf behaviour.

This stage is also where **brand strategy** should already be settled. The formulator needs to know whether this product is the flagship that defines the brand or a line extension that supports an existing hero. The answer changes how much the development effort is worth and how distinctive the formula has to be.

Stage two: selecting the active system

Most anti ageing serums draw on a small number of ingredient families, each with well-documented behaviour and well-documented formulation constraints. Choosing between them is the single most consequential technical decision in the project.

• **Retinoids.** Retinol and its esters, plus newer derivatives. Strong evidence base, but oxidation-sensitive, irritation-prone, require careful pH and packaging that excludes air and light. Also subject to concentration limits that vary by market.
• **Vitamin C.** L-ascorbic acid is effective but needs a low pH and is highly unstable in water; stabilised derivatives are easier to formulate and behave differently in terms of pH preference and sensory feel.
• **Peptides.** Generally well tolerated and formulation-friendly, with a wide usable pH range. Cost per kilogram is high, and dosing is usually low, so the perceived value has to be communicated rather than felt.
• **Hydroxy acids.** AHAs and PHAs improve surface texture and tone, but need a defined low pH to function, which conflicts directly with several other actives and with some preservative systems.
• **Niacinamide.** Versatile and popular, prefers a near-neutral pH, which is why combining it with low-pH acids or L-ascorbic acid in a single formula requires care.
• **Humectants and barrier support.** Hyaluronic acid of various molecular weights, glycerin, panthenol, ceramides. These do not drive the anti ageing claim but drive how the product feels, which drives repurchase.
• **Botanical extracts.** Often central to brand storytelling and common in Thai manufacturing, where herbal sourcing is a genuine strength. They bring colour, odour and batch variability that the formula has to accommodate.

The hard part is combination. Two actives that each work well can be incompatible at a shared pH, can destabilise each other, or can push irritation beyond acceptable levels. Experienced formulators will often propose splitting an ambitious concept into two products rather than compromising one. That recommendation is usually correct, even though it is commercially inconvenient.

When briefing a **skincare OEM**, state your preferred active direction and your non-negotiables, then let the laboratory propose the specific raw materials and levels. Specifying both the actives and their exact percentages without laboratory input is how brands end up with a formula that cannot be preserved or stabilised.

Stage three: the base, texture and delivery system

Buyers judge a serum in the first three seconds of application, long before any active can do anything. The base determines that judgement, and it is decided after the actives because the actives constrain it.

The main base options and what they imply:

• **Aqueous gel.** Light, fast-absorbing, suits humid climates and layering. Needs a thickener system, and the choice of thickener affects how the gel behaves at low pH and with electrolytes.
• **Water-in-oil or oil-in-water emulsion.** Richer, carries oil-soluble actives, leaves more of a cushioned finish. More complex to stabilise and more sensitive to temperature excursions in transit.
• **Anhydrous oil or ester serum.** No water means a simpler preservation picture and good carriage of oil-soluble actives, but the sensory profile is divisive and it will not suit every market.
• **Biphasic.** Visually distinctive, requires shaking, and needs a packaging decision that matches.
• **Encapsulated or liposomal delivery.** Can improve stability or tolerance of a difficult active. Adds cost and requires supplier-specific raw materials.

Beyond the base type, the specification should pin down measurable sensory targets: viscosity range, spreadability, absorption time, finish from matte to dewy, tackiness, and pilling behaviour under sunscreen or makeup. Pilling in particular is worth testing early, because it is one of the most common complaints about serums and it is a function of polymer and film-former choices, not of product quality in any general sense.

Colour and odour also need a decision now rather than later. A formula with a high botanical load or an oxidation-prone active will not be bright white and will not stay perfectly colour-stable; a brand that insists on a pristine white serum may be unknowingly forcing the removal of the ingredient it wanted to feature. Agree an acceptable colour and odour range in writing and keep a retained reference sample for comparison across batches.

Stage four: bench samples, feedback and pilot batches

Development moves from a few grams on a bench to a pilot batch that behaves like production. Each step has a purpose, and skipping one pushes the problem later, where it costs more.

1. **Bench trials.** The formulator prepares small laboratory batches exploring different approaches to the brief. You may see two or three directions rather than one proposal. 2. **First sample round.** You receive candidates to evaluate. This is where most brand owners lose time, because feedback like it feels a bit heavy gives the laboratory nothing to act on. 3. **Structured feedback.** Score each sample on fixed criteria: spread, absorption time, after-feel, tackiness, odour intensity and direction, colour acceptability, behaviour under your intended sunscreen or makeup, and performance in your target climate. Request at most two or three changes per round. 4. **Refinement rounds.** Each round should have a stated objective. Changing direction entirely mid-project resets the clock. 5. **Preservative efficacy and compatibility work.** Once the formula is close, the preservative system is validated against the final pH and the final active load. 6. **Pilot or scale-up batch.** A larger batch made with production equipment. Mixing shear, heating and cooling rates and order of addition all change at scale, and a formula that is perfect on a bench can behave differently here. Viscosity and appearance are re-checked and the process is documented. 7. **Formula and process lock.** The final formulation, specification and manufacturing procedure are fixed, and a retained standard sample is kept for future batch comparison.

How many rounds this takes depends on the complexity of the active system, the number of exclusions in the brief and how precise your feedback is. Rather than asking for a timeline up front, ask how the stages are structured and what is needed from you at each one; the schedule is confirmed at quotation and depends on the product.

One discipline is worth insisting on: every round gets a written record with sample code, date, formula version, your scores and the agreed next action. Projects that run on voice calls and chat messages are the ones that lose track of which version was actually approved.

Stage five: testing that supports shelf life and claims

Testing is not a formality at the end. It is what tells you whether the product you approved will still be that product after months in a warehouse and a container.

• **Stability testing.** Samples held at elevated temperature, at room temperature, refrigerated and through freeze-thaw cycles, with pH, viscosity, colour, odour and phase separation monitored at intervals. Accelerated conditions give early signals; real-time data confirms them.
• **Packaging compatibility.** The formula is tested in the actual primary packaging, because interaction between product and container is real. Low-pH formulas can attack certain metal components; essential oils and some solvents can affect plastics and dropper bulbs; a formula can also absorb into or leach from packaging materials.
• **Microbiological testing and preservative efficacy.** Challenge testing demonstrates that the preservative system controls contamination over the product's life, including after the consumer opens it.
• **Safety assessment.** A qualified assessment of the finished formula, which is a prerequisite for market authorisation in many jurisdictions.
• **Claim support testing.** If you intend to state a specific effect, that statement generally needs supporting evidence. Instrumental measurements and consumer perception studies are different kinds of evidence and support different kinds of wording.
• **Patch and tolerance testing.** Particularly relevant for retinoid and acid formulas aimed at sensitive users.

A caution on claims: the line between a cosmetic claim and a medicinal claim is where brands most often get into trouble, and the permitted wording differs by market. Build the claim language with your regulatory contact and the manufacturer together, before the packaging artwork is finalised, and verify current requirements with the relevant authority in each target market rather than copying wording from a competitor.

Testing also determines your period after opening and your shelf life. These are conclusions from data, not numbers to be chosen for commercial convenience, and they belong on the label.

Stage six: packaging, documentation and production handover

The last stage is where a good formula either reaches the market intact or quietly degrades on a shelf.

Packaging decisions follow the formula, not the mood board. For an anti ageing serum the main considerations are:

• **Oxygen and light exposure.** Retinoids, L-ascorbic acid and many botanicals degrade with air and light. Airless pumps and opaque or UV-protective containers protect them; wide-mouth jars and clear glass do not.
• **Dose control.** A dropper suits oil and thin aqueous serums; a pump gives more consistent dosing and less contamination; a fine mist suits very light fluids.
• **Material compatibility.** Confirmed by the compatibility testing above, not assumed.
• **Fill volume against usage.** A serum that oxidises is better in a smaller fill the user finishes quickly than in a large bottle that sits half-empty.

Work through **Thai packaging suppliers** or your manufacturer's packaging team with the formula specification in hand, and ask for component specifications and material declarations in writing so they can be attached to your product file.

The documentation set you should expect to receive or jointly build includes the finished formula and specification, the manufacturing procedure, raw material specifications, test reports from stability and microbiology, the safety assessment, label artwork reviewed against regulatory requirements, and batch documentation for each production run with batch numbers and retained samples.

Two commercial points to settle in writing before production. First, ownership of the formula and confidentiality terms: for a custom development these are negotiable and should be explicit rather than assumed. Second, order quantity. For OEM and ODM production the standard minimum is 1,000 units per SKU, which is exactly why launching with one well-chosen serum rather than a four-product line is the more capital-efficient decision for a new brand. Pricing depends on the product and quantity and is confirmed by the team at quotation.

If you are comparing more than one **OEM manufacturer in Thailand**, compare them on this stage as much as on sample quality. The manufacturer that produces a slightly less impressive first sample but delivers complete documentation and a locked, repeatable process is usually the better long-term partner.