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Zinc oxide mineral sunscreen OEM/ODM manufacturing
Zinc Oxide Mineral Sunscreen · OEM/ODM
Zinc oxide (ZnO) is a white mineral powder, insoluble in water, permitted as a UV filter by Annex VII of the ASEAN Cosmetic Directive in its regular form (Ref A29) and nano form (Ref A29a), up to 25%, and when both forms are used the total may not exceed 25%. It is often called a "physical sunscreen", but zinc oxide actually absorbs UV across a broad range covering both UVB and UVA, rather than only reflecting it (Schneider and Lim, 2019). In volunteers, zinc oxide nanoparticles applied repeatedly for 5 days stayed on the skin surface and in skin furrows and did not enter the viable epidermis (Mohammed et al., 2019); what does enter the skin is dissolved zinc ions (Holmes et al., 2016). In return, a zinc oxide sunscreen brings two problems of its own: the higher the concentration, the more visible the white cast (Maldonado Lopez et al., 2025), and concentrated zinc oxide formulas often give lower SPF values in vitro than SPF measured on people (Osterwalder et al., 2024). This page differs from the general sunscreen page because zinc oxide is the named filter: the formula is built around powder dispersion, white cast across many skin tones, the nano dossier and the right SPF test method. SPF and UVA values are labeled only once they have been measured on the finished product. Butter-C offers turnkey OEM/ODM manufacturing, from formula development and coordination of sun protection testing to labeled finished goods and the notification dossier.
Formula base
Zinc oxide as the named filter, a base that keeps the powder evenly dispersed
The filter determines UV filtering; the oil base, dispersant and emulsifier determine whether the powder spreads into an even layer on the skin. Butter-C checks the current Annex VII (version 2025-2, 12 December 2025) when building the formula.
Zinc Oxide
CAS 1314-13-2. Annex VII Ref A29 (zinc oxide) and Ref A29a ("Zinc Oxide (nano)"): maximum 25%; footnote (2): when both forms are used, the sum may not exceed 25%. Both entries state "Not to be used in applications that may lead to exposure of the end-user's lungs by inhalation". Particle size, whether there is a surface coating and whether the material is nano are confirmed from the technical data sheet (TDS) and the certificate of analysis (COA) of each lot; the coating agent must also appear in the ingredient list.
Oil base carrying the powder
Esters and triglycerides such as C12-15 Alkyl Benzoate, Caprylic/Capric Triglyceride and Dicaprylyl Carbonate wet and carry the powder; caprylic/capric triglyceride was also the oil base of one of the three zinc oxide nanoparticle formulations in a skin penetration study (Holmes et al., 2016). Choose a hydrophobically coated zinc oxide for the oil phase or a hydrophilically coated one for the water phase, with a dispersant and enough milling or homogenization to prevent agglomeration (manufacturing practice).
Emulsifier system
A water-in-oil emulsion with Polyglyceryl-2 Dipolyhydroxystearate (which both emulsifies and helps disperse mineral powders) and an electrolyte in the water phase; or an oil-in-water emulsion with a suspension stabilizer. The system is chosen for the desired skin feel and for stability and dispersion results (formulation experience).
No acidic base
Zinc oxide dissolves in dilute acids (PubChem); an aqueous suspension at pH 6 gave a higher zinc ion signal in skin than one at pH 9 (Holmes et al., 2016). Acids such as AHAs, BHA or ascorbic acid are therefore not combined in the same formula; the pH of the water phase is set and monitored on the sample.
Iron oxides (tinted version)
Iron Oxides (CI 77491, 77492, 77499) are Annex IV colorants, not UV filters. In a study in 12 volunteers comparing four products, the tinted products protected better against visible light plus UVA1 than the untinted ones (Ezekwe et al., 2024) — a result of the whole formula.
Key technical points
Four issues specific to a zinc oxide sunscreen
The four items below are settled on the sample before it goes for SPF testing — changing the powder source, the dispersant or the oil ratio after testing can change the result.
Dispersion without agglomerates
Agglomerated powder makes the layer on the skin uneven and the white cast more visible. The powder is pre-wetted in the oil phase with a high-speed homogenizer, or a supplier's ready-made dispersion is used; agglomerates are checked under the microscope on every sample (manufacturing practice).
White cast and concentration
In a study that built a white cast scoring scale (13 volunteers plus expert graders, measured in vivo and in vitro), increasing the zinc oxide percentage increased whiteness (L*) and white cast, and the higher levels gave unacceptable white cast (Maldonado Lopez et al., 2025; all authors were employees of the sponsoring company). Butter-C scores white cast on several skin tones to balance the zinc oxide level against the target value.
Measuring SPF with the right method
The reference method is in vivo testing under ISO 24444:2019. A review found that formulas containing 10–25% zinc oxide often give lower SPF in vitro than in vivo, possibly because their high density (about 1.3–1.7 g/mL) makes the test film on the plate thinner (Osterwalder et al., 2024). The method and the laboratory are agreed at the start, according to the requirements of the target market.
Nanoparticles and inhalation
If nano zinc oxide is used, the material must meet the criteria of Ref A29a: purity ≥ 96% with wurtzite crystal structure, clusters that are rod-like, star-like and/or isometric, impurities consisting only of carbon dioxide and water with other impurities below 1% in total; median particle number size D50 > 30 nm and D1 > 20 nm; water solubility < 50 mg/l; and coating materials demonstrated to be safe and not to affect the nanoparticle properties — the supplier's dossier is kept in the PIF. Neither the regular nor the nano form is used in sprays or loose powders that could be inhaled into the lungs.
Three formulation directions
Three formats of zinc oxide sunscreen
Untinted mineral-only zinc oxide cream
Zinc oxide is the formula's UV filter, with no organic filters. Aimed at people who want to avoid organic filters — the Maldonado Lopez (2025) authors state that mineral sunscreens suit people with sensitive skin or allergies to organic filters. The challenge is white cast on darker skin; the achievable value depends on the test result and is not promised in advance.
Tinted zinc oxide cream
Iron oxides are added so the cream matches skin tone and shows less white cast. According to the review cited in our iron oxides article, the product layer must be visible on the skin to block visible light; nano zinc oxide on its own does not block this range. Each shade is a separate formula and a separate test.
Hybrid zinc oxide – organic filters
Zinc oxide combined with organic filters from Annex VII to lower the powder level and the white cast. One study found that zinc oxide (micro- or nano-sized) caused significant photodegradation of five SPF 15 organic filter mixtures after 2 hours of UV exposure, and the degraded mixtures were more toxic in zebrafish embryos (Ginzburg et al., 2021) — so the hybrid version requires a photostability test on the formula itself. A hybrid version may not be called "mineral filters only".
Packaging is planned with the formula
Multilayer tubes or pump bottles; checks for powder settling, oil separation at the tube neck and plastic compatibility. No sprays or loose powders, because both Ref A29 and A29a exclude applications that may lead to inhalation into the lungs.
Parameters we monitor
What our R&D team 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.
- SPF
- The labeled value is measured on people under ISO 24444:2019 at a laboratory whose ISO/IEC 17025 accreditation covers this method; in vitro screening results are used only during formula development.
- UVA protection
- Measured under ISO 24443:2021 (UVA protection factor, critical wavelength); the UVA symbol on the label follows the rules of the target market, since the ASEAN sunscreen labeling guideline does not set a specific symbol.
- Water resistance
- Tested under ISO 16217:2020 when the label says "water resistant".
- Zinc oxide content
- Per formula, with regular plus nano forms not exceeding 25% in total; COA of the powder for each lot (purity, particle size, coating) and a check on the finished product by the testing laboratory's method.
- White cast, color
- Whiteness (L*) measurement and white cast scoring on several skin tones; for the tinted version, each lot is color-matched to the reference sample.
- Dispersion and stability
- Centrifugation, freeze–thaw cycling, storage at 40 °C; monitoring for powder settling, oil separation, lumps and color change; agglomerates checked under the microscope.
- Water-phase pH
- Measured on the sample and at each stability time point; not allowed to drift into the acidic range.
- Photostability (hybrid version)
- UV absorbance of the formula before and after UV exposure when organic filters are used alongside zinc oxide.
- Microbiology & preservative challenge
- Tested at a GLP / ISO 17025-accredited laboratory; preservative efficacy test under ISO 11930.
Claims
Writing claims within the cosmetic scope
Every number on a sunscreen label must be backed by a test report on the finished product itself in the Product Information File. Wording follows the ASEAN sunscreen labeling guideline (Appendix X, Revision 02, 18 November 2025); whether this guideline is mandatory needs regulatory confirmation, and Butter-C applies it as a minimum. Butter-C reviews the wording on the label and in marketing materials when preparing the notification dossier.
Helps protect skin against UVB; "broad spectrum" and "UVA protection" only once UVA has been measured on the finished product
Instead of: blocks UV completely, total sun protection, "sunblock".
SPF and PA according to the test result; SPF above 50 labeled "SPF 50+"
Instead of: values calculated from the ingredient list, SPF 80 or SPF 100.
Zinc oxide mineral UV filter
Instead of: "only reflects UV" (zinc oxide absorbs UV rather than only reflecting it — Schneider and Lim, 2019), "does not enter the skin at all" (dissolved zinc ions do reach the stratum corneum and epidermis — Holmes et al., 2016); a hybrid version is not labeled "mineral filters only".
Directions to apply enough and reapply after sweating, swimming or toweling
Instead of: all-day protection, no need to reapply.
Mandatory label warning
"Do not stay too long in the sun, even while using a sunscreen product" (Annex VII, for primary sunscreen products) — printed in the equivalent Vietnamese, with the translation approved by regulatory affairs.
An option for people who want to avoid organic filters (mineral-only version); try on a small area of skin first
Instead of: non-irritating, safe for every skin, completely safe for children and pregnant women. The product is not positioned for children: sunscreens for children need a separate safety assessment for the age group, and for infants a pediatrician should be consulted.
Water resistant; helps protect against visible light (tinted version) — only once tested on the finished product
Instead of: won't wash off, fully waterproof, prevents skin cancer, drug-like claims about melasma or tanning.
Manufacturing specifications
Current capabilities
- Texture
- Sunscreen cream or lotion, untinted or tinted.
- Pack formats
- Tubes, pump bottles. No sprays or powders containing zinc oxide. Volume agreed when packaging is selected.
- Minimum order quantity
- Agreed per order — depends on the formula direction, the number of shades and the pack format chosen.
- Testing
- Quality parameters tested at a GLP / ISO 17025-accredited laboratory; SPF and UVA measured at a specialized testing facility.
- Dossier
- Product Information File (PIF) with SPF and UVA reports, the zinc oxide COA and the nanomaterial dossier when the nano form is used; notification dossier prepared by Butter-C.
- Packaging
- Label design with the mandatory sunscreen warning and reapplication directions; printing and packing run in parallel with formula work.
Suggested product concept
Tinted zinc oxide face sunscreen
A product concept to help you picture the possibilities, not a ready-made product for sale. The actual formula is developed to match your brand positioning and price range.
Non-nano zinc oxide
The named mineral filter; the level is set by the SPF measured on the finished product and the white cast score, never above 25%.
Iron oxides matched to skin tone
Makes the cream match the skin and reduces white cast; the number of shades is agreed with you.
Water-in-oil emulsion
A light ester base and dispersant help the powder spread evenly; fragrance-free.
50 ml tube
The label carries the mandatory sunscreen warning and directions to apply enough and reapply.
Customization options
What you can specify
The same product type can serve very different customer groups depending on the brand. Tell us your requirements in the areas below and our team of pharmacists will develop a matching formula.
Target values
Desired SPF and UVA level — the final number follows the test result on the finished product.
Regular or nano particles
Nano reduces white cast but needs a dossier meeting the Ref A29a criteria and the correct name in the ingredient list.
Mineral-only or hybrid
Mineral-only for a "mineral filters only" story; hybrid for less white cast, with a photostability test.
Untinted or tinted
Untinted, one shade or several shades — each shade is a separate test.
Texture
Rich cream for dry skin or a thin, dry-touch lotion for oily skin.
Target market
Domestic only or export — the list of permitted filters, how the nano form is labeled and the UVA symbol differ from country to country.
Further reading
Related topics
Zinc oxide in cosmetics
How it filters UV, skin penetration data for nanoparticles, white cast and the conditions of Annex VII (in Vietnamese).
Facial sunscreen manufacturing
The three filter systems — organic, inorganic and hybrid — for sunscreens in general.
SPF: what it means and how it is tested
ISO methods and the ASEAN sunscreen labeling guideline (in Vietnamese).
Iron oxides in cosmetics
Tinted sunscreens and the data on visible light (in Vietnamese).
Using sunscreen correctly
How much to apply, when to reapply and label wording not to trust (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 →
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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