Sun-care formulators rarely buy a single UV filter. They buy a combination, and the combination has to work as a physical system before it works as anything else. Two things about that system are routinely missed at the specification stage, and both cause avoidable problems on receipt: most UV filters are liquids, not powders, and their assay specifications legitimately exceed 100%.
What form each filter actually arrives in
Across SpecNexa’s supply base, the commonly specified organic UV filters are supplier-declared as follows:
| Filter | CAS | Physical form | Assay range | Packaging |
|---|---|---|---|---|
| Avobenzone | 70356-09-1 | Crystalline powder (white to light yellow) | 95.0–105.0% | 25 kg drum |
| Octocrylene | 6197-30-4 | Viscous liquid (transparent yellow) | 95.0–105.0% | 25 kg drum, 200 kg barrel, or 1000 L IBC |
| Octyl methoxycinnamate | 5466-77-3 | Liquid (colourless to light yellow) | 95.0–105.0% | 200 kg drum |
| Octyl salicylate | 118-60-5 | Liquid (clear, colourless to slightly yellowish) | 95.0–105.0% | 200 kg drum |
| Homosalate | 118-56-9 | Liquid (colourless, transparent) | 90.0–110.0% | 25 kg or 200 kg drum |
Note the pattern: four of the five are liquids. Avobenzone is the outlier. If your specification, purchase order, or incoming-goods procedure assumes drums of powder across the board, four of these five will not match what arrives.
Why the solid-versus-liquid split drives the whole specification
Avobenzone being a crystalline solid is the constraint the rest of the formulation works around. A solid filter has to be dissolved before it can be distributed evenly through an emulsion, and the oil-soluble liquid filters in the same list are what it is typically dissolved into. In practice the liquid filters serve two functions at once: they are UV filters in their own right, and they are the solvent phase carrying the solid one.
That has direct consequences for how you specify:
- You cannot specify the solid in isolation. The quantity of liquid filter available to dissolve it constrains how much avobenzone the formulation can actually carry.
- Ratios matter more than individual levels. Changing one filter’s level changes the solvent capacity available to the others.
- Substitution is not free. Swapping one liquid filter for another changes the solvent system, not just the filter profile.
Confirm solubility behaviour in your own base rather than assuming it transfers from a previous formulation. Suppliers can advise, but the system is yours.
Why an assay range above 100% is not an error
A specification reading 90.0–110.0% looks wrong at first glance. It is not, and the reason matters when you are comparing offers.
Assay for materials of this type is conventionally expressed against a declared content rather than as an absolute proportion of the drum. A result of 104% means the measured content came in slightly above the nominal declared figure, within the tolerance the method and the reference standard allow. Pharmacopoeial and cosmetic monographs routinely define such ranges with an upper bound above 100 for exactly this reason.
What this means practically:
- A range is the specification. A single number is not. “Homosalate 110%” on its own is meaningless — it is the upper bound of 90.0–110.0% with the lower bound dropped.
- Always ask for both bounds. If a quotation shows one figure, ask which end it is. This is the single most common documentation gap in this category.
- A wide range is a different product from a narrow one. 90–110% is a materially looser specification than 95–105%, and the two should not be priced against each other as equivalent.
Permitted filters and use levels are set by market
Which UV filters may be used, and at what maximum level, is determined by the regulator in each destination market, and the lists differ between the EU, the United States, and other jurisdictions. A filter permitted in one market at one level may be permitted at a different level, or not permitted, in another.
This is the buyer’s responsibility to confirm for the market being supplied, before formulating and before committing to volume. A supplier specification states what the material is; it does not establish that the material is permitted in your product for your market. Confirm the current position with the applicable regulator or your regulatory adviser, since these lists are periodically reviewed and revised.
Packaging and freight are part of the decision
The liquid filters ship in 200 kg drums, and octocrylene is also available in 1000 L IBC containers; avobenzone ships as a 25 kg powder drum. That difference affects landed cost, storage, and how much you are committing to per order. If your production volumes do not justify a 200 kg drum of a liquid filter, say so in the RFQ — smaller packaging is sometimes available and is worth asking about before you are quoted against a drum you cannot use.
All five are declared for storage in tight, light-resistant containers.
What to include in your RFQ
- Each filter by name and CAS number — CAS removes any ambiguity between naming conventions.
- The assay range you require, both bounds, and the assay method.
- Physical form expected — state it, so a mismatch surfaces at quotation rather than at goods-in.
- Packaging size, and whether smaller units are needed.
- Destination market, which governs permitted status and use level.
- Annual volume per filter — combinations are usually quoted as a set.
- Documentation — certificate of analysis showing method and both bounds, specification sheet, and safety data sheet.
Sourcing UV filters through SpecNexa
All five filters above are listed with supplier-declared assay ranges, CAS numbers, physical form, and packaging. If you are specifying a combination, include the full set in a single request so the offers can be compared as a system rather than line by line.
All specification information is supplier-declared and provided for sourcing discovery. Buyers should confirm the final agreed specification, including both assay bounds, method, physical form, packaging, and batch documentation, directly with the contracting supplier.