Custom sunscreen manufacturing starts with a product specification covering SPF, UVA protection, texture, water resistance, packaging, target market, and permitted UV filters. A manufacturer then develops laboratory batches, tests physical stability and microbial quality, verifies SPF and UVA performance, scales the formula to production equipment, fills approved packaging, and releases each batch after quality checks. SPF cannot be assigned from UV-filter percentages alone: ISO 24444:2019 specifies an in-vivo SPF test, while ISO 24442:2022 covers in-vivo UVA protection measurement. In the U.S., water-resistant sunscreen claims must be supported for either 40 or 80 minutes under FDA testing requirements.
Manufacturing usually begins with a specification sheet rather than a formula. A brand may request SPF 30 or 50, a lotion viscosity of roughly 10,000–40,000 cP, fragrance-free positioning, a matte finish, mineral filters, organic filters, or a combination permitted in the destination market.
That specification controls ingredient selection because sunscreen rules differ by jurisdiction. A formula intended for the U.S. must follow applicable OTC sunscreen requirements, while products developed for European or other international markets may use a different set of permitted UV filters and claim-testing methods.
The manufacturer then builds several bench samples, often in batches of about 0.5–5 kg, so adjustments can be made without wasting commercial quantities of raw material. A first prototype may contain more than 15–25 ingredients once UV filters, emollients, emulsifiers, thickeners, humectants, preservatives, antioxidants, chelating agents, and processing aids are counted.
UV-filter selection comes before many sensory adjustments because each filter has different solubility and spectral behavior. Zinc oxide and titanium dioxide are particulate mineral filters, while many organic filters must remain dissolved in the oil phase to avoid crystallization during storage.
A filter system also has to cover both UVB and UVA rather than simply produce a high SPF number. ISO 24442:2022 provides a method for measuring UVA protection factor, while ISO 24444:2019, confirmed as current by ISO in 2026, covers in-vivo SPF determination.
A sunscreen with the same nominal percentage of UV filters can return a different measured SPF after changes to emollients, film formers, dispersion quality, viscosity, or application behavior.
That relationship is why the base formula receives almost as much attention as the filters. Oils must keep oil-soluble filters dissolved, emulsifiers must hold the water and oil phases together, and rheology modifiers must produce a viscosity suitable for both application and filling.
A manufacturer may prepare the water and oil phases separately at approximately 70–80°C when the emulsion system requires heating. The phases are then combined under controlled agitation, and high-shear homogenization may run for several minutes before cooling begins.
Processing order matters because a polymer added before complete hydration may form lumps, while a mineral dispersion exposed to insufficient shear can remain uneven. Production records therefore specify temperature ranges, mixing speed, addition sequence, and mixing duration rather than relying on operator judgment.
Cooling can be equally important. A formula may remain smooth at 75°C but thicken sharply below 40°C, so fragrances, preservatives, heat-sensitive botanical materials, or certain skincare ingredients are often added only after the batch reaches an approved temperature range.
Laboratory screening follows because a visually acceptable lotion on day 1 does not establish shelf stability. Samples may be stored at room temperature, elevated temperature, refrigerated conditions, or through repeated temperature cycles while technicians compare appearance, odor, viscosity, pH, separation, sedimentation, and crystallization.
Accelerated storage commonly includes elevated conditions such as 40°C, although the actual protocol depends on the company and product. Measurements may be recorded at several checkpoints over weeks or months, creating a trend rather than relying on a single observation.
| Manufacturing area | Typical item checked | Why it is measured |
|---|---|---|
| Bulk emulsion | pH, viscosity, appearance | Confirms batch consistency |
| UV-filter system | Dispersion or solubility | Reduces settling or crystallization risk |
| Stability samples | Heat and temperature cycling | Screens physical changes |
| Packaging | Leakage, pump output, compatibility | Confirms formula-container performance |
| Finished batch | Microbiology and specifications | Supports batch release |
Packaging enters development before commercial production because the formula can interact with its container. A thick mineral sunscreen may not pass easily through a narrow pump, while lower-viscosity products can leak if the closure system or seal is unsuitable.
A manufacturer may therefore fill dozens of compatibility samples into the intended tubes, bottles, pumps, or sticks and store them with the stability batches. Weight loss, paneling, swelling, seal damage, discoloration, leakage, and changes in dispensing are inspected during the same storage period.
Microbiological control is another separate part of development. Water-containing sunscreen normally needs a preservation system able to control microorganisms during manufacture, storage, and repeated consumer use, and performance can change when pH, surfactants, plant extracts, or packaging are modified.
Preservative efficacy testing exposes the finished formula to defined microorganisms and checks how the microbial population changes over specified intervals. The purpose is to evaluate the actual formula rather than assuming that a preservative used at, for example, 0.5% or 1% will behave identically in every emulsion.
Once stability and microbiological screening are acceptable, protection claims need measurement. Under the FDA broad-spectrum test, the UV transmission spectrum is evaluated from 290 to 400 nm, sunscreen is applied to PMMA plates at 0.75 mg/cm², and at least five transmittance measurements are taken on each of three plates.
SPF testing is handled separately. ISO 24444:2019 provides an in-vivo method for determining SPF and was published in December 2019; an amendment followed in 2022. A manufacturer may use preliminary instrumental screening during formulation, but market claims have to follow the test requirements applicable to the destination country.
UVA claims require their own measurement approach. ISO 24442:2022 specifies an in-vivo UVA protection factor method, so an SPF 50 result by itself does not provide a complete numerical description of UVA performance.
For markets and labeling systems where PA ratings are used, a PA+++https://www.ymcosmetic.com/news_detail/pa_sunscreen_what_private_label_brands_need_to_know.html+ sunscreen is positioned around a high UVA protection grade rather than SPF alone. Manufacturers therefore have to develop the UVA side of the filter system alongside UVB protection instead of treating PA as a packaging statement added after formulation.
Water resistance adds another test requirement. In the U.S., the FDA permits labeled water-resistance periods of 40 or 80 minutes when the product meets the prescribed testing procedure; terms such as “waterproof” and “sweatproof” are not permitted sunscreen claims.
For a 40-minute claim, the FDA procedure uses two 20-minute water-immersion periods separated by 15-minute drying periods. An 80-minute claim requires four immersion-drying sequences before the remaining SPF testing steps continue.
Water resistance comes from the complete dried film on skin, so increasing one film-forming polymer does not automatically produce an 80-minute result.
Once the laboratory formula passes the required development work, scale-up begins. Moving from a 1 kg bench batch to 100 kg or 1,000 kg changes heat-transfer rate, circulation, homogenizer loading, powder wetting, air incorporation, cooling time, and transfer losses.
A mixing process that takes 5 minutes in a laboratory vessel may need a different shear rate or circulation pattern in a production tank. Manufacturers therefore create a master manufacturing procedure after pilot work rather than multiplying every laboratory time and speed by the same scale ratio.
Pilot production also checks practical losses. Product can remain on vessel walls, transfer hoses, filters, pumps, and filling equipment, so theoretical batch weight and usable filled quantity are rarely identical.
If a 500 kg bulk batch produces 485 kg available for filling, the practical yield is 97%. Yield limits are normally established in manufacturing records so unusual losses can be investigated before the lot is released.
Raw materials are controlled before they enter that vessel. Each received lot can be checked against specifications covering identity, appearance, odor, assay, particle characteristics, microbiological limits, or other parameters relevant to the ingredient.
Mineral dispersions deserve close attention because particle distribution and dispersion properties can affect whitening, viscosity, sedimentation, and application uniformity. Organic-filter raw materials also require controlled identity and purity because substitution with another grade may change solubility or processing behavior.
During production, operators record batch temperature, mixing time, ingredient lot numbers, quantities, pH, viscosity, and other in-process results. A 2% weighing error in a low-level ingredient can be far more significant than the same percentage error in purified water, so calibrated weighing equipment and independent checks are commonly built into controlled production procedures.
Filling starts only after the bulk meets the required specifications. Tubes, bottles, airless pumps, sticks, and sachets each need different filling equipment, and the fill temperature may be adjusted to suit the viscosity and package without damaging formula structure.
Fill-weight checks are performed repeatedly during the run rather than only on the first package. If a nominal 50 g unit is being produced, the manufacturer sets internal acceptance limits and checks multiple units at defined intervals to keep the line within specification.
The U.S. label also has requirements beyond the SPF number. FDA guidance states that products meeting the broad-spectrum test may carry “Broad Spectrum SPF” labeling, while eligible water-resistant products must state either 40 minutes or 80 minutes rather than making an unrestricted water-resistance claim.
Finished-product release then compares the batch against approved specifications. Depending on the formula, testing can include appearance, odor, pH, viscosity, fill weight, packaging integrity, microbial quality, and chemical measurements associated with the UV-filter system.
Traceability links the finished lot to raw-material lots, manufacturing records, equipment records, packaging batches, testing results, and release approval. If a later complaint identifies one production lot, the manufacturer can review that lot rather than treating every unit produced since 2024, 2025, or 2026 as the same manufacturing event.
Custom development also differs from simple private labeling. An existing private-label base may need only packaging selection and limited brand adjustments, while a new sunscreen can require multiple laboratory revisions, stability work, protection testing, compatibility evaluation, pilot manufacturing, and updated documentation.
Cost therefore comes from more than bulk cream. UV filters, specialized emollients, mineral dispersions, laboratory testing, packaging tooling, minimum order quantities, pilot batches, failed prototypes, and external claim testing all contribute to the finished unit cost.
A formula intended for several countries can add further work because one ingredient system may not fit every regulatory framework. Manufacturers commonly define intended markets before development so permitted filters, claim wording, test methods, package information, and documentation can be reviewed before hundreds of kilograms are produced.
Manufacturing competence is easier to assess through records than sales language. A brand can ask how the company controls raw-material changes, how many pilot batches are normally produced, which SPF and UVA methods are used, how stability failures are handled, and whether retained samples are kept from commercial lots.
The same review should cover production tolerances. A manufacturer should be able to explain acceptable ranges for pH, viscosity, fill weight, bulk yield, and other measurable properties and show how an out-of-specification result is investigated.
A commercial sunscreen is therefore developed through repeated measurable stages: bench batches, stability screening, microbiology, SPF and UVA testing, packaging compatibility, pilot manufacturing, commercial scale-up, filling, and lot release. ISO 24444:2019 and ISO 24442:2022 illustrate why protection claims are treated as measured finished-product properties rather than estimates derived from an ingredient list.