Tinosorb S vs M: What the Data Sheets Actually Say

Search for these two filters and you’ll be told, over and over, that one is oil soluble and the other is water soluble. The second half of that is wrong, and the document that proves it is a European safety committee report that lists the water solubility of Tinosorb M’s active molecule as “extremely low solubility in water (< 5 ng/L at 25 °C)”.^[3] So if it isn’t dissolving in water, what is it doing in the bottle? We opened both manufacturer data sheets and both committee opinions to find out.

One arrives as a powder, the other arrives as a liquid

Each data sheet has a field called Physical form on its first page. For Tinosorb S it reads “Light yellow powder”.^[1] For Tinosorb M it reads “White liquid”.^[2] That single line explains most of what follows.

What the sheet says	Tinosorb S[1]	Tinosorb M[2]
Name on a label	Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine, or Bemotrizinol in US listings	Methylene Bis-Benzotriazolyl Tetramethylbutylphenol, or Bisoctrizole in US listings
Physical form	Light yellow powder	White liquid
What you’re buying	100 percent active	48.0 to 52.0 percent active, 36.9 to 45.7 percent water
Molecular weight	628 g/mol	659 g/mol
CAS number	187393-00-6	103597-45-1
Sheet we read	PRD 30481068, Revision 1.0, valid since 02.08.2018	PRD 30482916, Revision 1.1, valid since 12.03.2019

The third row is the one that changes how a formulator works. A drum of Tinosorb S is nothing but filter. A drum of Tinosorb M is close to half water, plus small amounts of decyl glucoside, propylene glycol and xanthan gum, which are there to keep the particles apart and stop them settling.^[2] A formulator who wants 3 percent of the actual filter in a finished sunscreen has to add roughly 6 percent of the Tinosorb M dispersion to get there, and that 6 percent brings water and a thickener along with it.

The Tinosorb S sheet includes a solubility table that makes the other side just as concrete. It dissolves at 17.0 percent by weight in ethylhexyl methoxycinnamate, 12.0 percent in C12-15 alkyl benzoate, and 5.0 percent in caprylic/capric triglyceride. In ethanol it manages “< 0.5”.^[1] So it has to be dissolved into an oil, and a heavier cosmetic ester takes up far more of it than a light alcohol does.

Am I choosing between two rivals, or between two different tools?

They are two different tools, and plenty of formulas use both. The Isntree Hyaluronic Acid Watery Sun Gel we read line by line lists Tinosorb S and Tinosorb M on the same label, two positions apart. Because Tinosorb S dissolves into the oily part of a formula and Tinosorb M does not dissolve at all, a formulator can dose them independently, and they end up in different parts of the same mixture.

BASF describes the M dispersion as one that “can be post-added to emulsions and is therefore suitable for cold process formulations”.^[2] That means it can go in near the end of the batch, without heating. Tinosorb S has to be dissolved into oils, which usually means it goes in early and warm. So the choice a formulator faces is often less about UV coverage than about which stage of the process has room for it.

The spectra are not measured the same way, and M’s shifts when the particles do

One trap first. BASF’s quality control page for Tinosorb S monitors absorption in 2-propanol at 341 nm, while the page for Tinosorb M monitors absorbance in a DMA and IPA mix at 346 nm.^[1][2] Those are batch release checks in two different solvents. They are not peak positions, and lining them up beside each other would tell you nothing, so we won’t.

For Tinosorb S, the number BASF states publicly is this, from its June 2026 release: “With absorption peaks at approximately 310 nm and 340 nm, it provides comprehensive protection across the wavelengths most responsible for skin damage and premature aging.”^[8]

A note on our own back catalog, because you may have read it: our guide to Korean sunscreen filters used to print the second peak as 345 nm, taken from an ingredient database entry rather than from the manufacturer, whose own release says approximately 340 nm. We removed that figure on 2026-07-30 rather than swap in a third number, so the only second-peak value we now print for this filter is the one BASF prints itself.

Tinosorb M is stranger, and the European committee file spells out why. Reporting work by Herzog and colleagues, it records that the spectrum of the molecule dissolved in dioxane has two bands, with “The band at about 305 nm arises from a local transition within the benzotriazole moiety.” Then the particles change it: “The absorption spectrum of micronised particulate MBBT in dispersion shows distinctive differences to that in solution, which are not explained by the additional scattering effect: The longer wavelength band is shifted to 360 nm and is followed by a shoulder at 380 nm. The short wavelength band at 305 nm shows no significant shift, but there is an additional shoulder at 320 nm.” The report attributes the shift to “electronic interactions of the chromophores in the particles”, meaning the light absorbing parts of neighboring molecules affect each other once they are packed into a solid particle, and it says the changes “depend on the particle size”.^[3]

Those are two different situations. Tinosorb S has an absorption spectrum, and Tinosorb M has an absorption spectrum that moves depending on how finely it was milled, in the direction that matters for long UVA. The same file measures the milled material at “a d(0.5) of 150 ± 9 nm (mass based)”, d(0.5) being the size that half the material by weight falls below, and reports that “The smaller the particles become, the more efficient they absorb UV, due to a larger surface area and a more even distribution in the vehicle as compared to larger particles.”^[3]

The dossier then claims the finished particles reach “about 90 % of the highest possible performance” at 360 nm, and the committee pushes back on that in the next paragraph: “The authors of the dossier did not specify how they determine the ‘highest possible performance’. In general and as stated in Horn and Rieger (2001), it remains a complex issue to relate the UV absorption of nano-emulsions to the bulk absorption properties.”^[3] We’re quoting the challenge along with the claim, because the claim on its own reads like a spec and it isn’t one.

If particle size in sunscreen is a thread you want to pull, our piece on nano and non-nano zinc covers the same argument on the mineral side. And the visible consequence of a particle filter, the faint cast some people see, we’ve handled at length in the no white cast explainer and in our guide for deep skin tones. We won’t re-argue it here. If you want the chemical-versus-mineral-versus-hybrid picture before going deeper on these two, our Korean sunscreen guide is where to start.

Each one holds up the rest of the bottle, by a different route

Both filters help the others in the bottle survive sunlight, and BASF names a different mechanism for each: chemical stabilization for one, physical scattering for the other.

For Tinosorb S, the data sheet says it is “an efficient performance booster with excellent photostability” and “an outstanding stabilizer for photoinstable UV filters”.^[1] There is an independent paper behind that claim. Chatelain and Gabard tested it in oil in water sunscreens under a filtered xenon arc and reported that “Tinosorb S prevented the photodegradation of AVB in a concentration-dependent way, leading to a sustained SPF and UVA ratio even after irradiation with doses of up to 30 MED”, where AVB is avobenzone and MED is the mean effective dose the paper uses as its unit of light. They add that “Since AVB was shown to destabilize ethylhexyl methoxycinnamate (EHM) we tested the effect of Tinosorb S in sunscreens containing this UV filter combination. Here too Tinosorb S showed photoprotective properties toward both UV filters.”^[7] The phrase to hold on to is concentration-dependent, since the paper ties the size of the effect to how much went in. At a trace level it will not do that job.

For Tinosorb M, the route BASF names is physical rather than chemical: it “boosts the performance of all oil soluble UV filters thanks to its scattering properties related to its particulate form”.^[2] That wording points at scattering rather than at chemical stabilization. The same page says the dispersion “shows absorption over the whole UV range and reaches even protection into the visible (blue) light” and that “Thanks to its strong absorbance in the UVA-we range, Tinosorb M shows strong contribution to the UVA-PF”, which is the lab number for how much UVA a formula holds back.^[2]

So both of them end up supporting the same thing, UVA protection that survives a day outdoors, by different means. That is as close to an answer as this comparison gets.

Why does one of them have a thicker regulatory file?

Because a dissolved molecule and a suspension of particles raise different questions, and the European committees answered them 16 years apart.

In February 1999 the SCCNFP looked at the Tinosorb S molecule, took three pages, and wrote two short sentences: “The SCCNFP is of the opinion that 2,4-bis-{[4-(2-Ethyl-hexyloxy)-2-hydroxy]-phenyl}-6-(4-methoxyphenyl)-(1,3,5)-triazine is safe for use in cosmetic products as a UV light absorber at a maximum concentration of 10%.” and “The SCCNFP proposes no further restrictions or conditions for its use in cosmetic products.” Under percutaneous absorption, which is how much of a substance passes through skin, its line reads “Very low absorption observed”.^[4]

In March 2015 the SCCS looked at the nano form of the Tinosorb M molecule and took 83. It concluded that the nano form used as a UV filter at up to 10 percent in dermally applied cosmetic products “is considered to not pose a risk of adverse effects in humans after application on healthy, intact skin”, but it attached specifications, including that “The material has a median particle size (d0.5) of 120 nm or larger in terms of mass distribution, and/or 60 nm or larger in terms of number size distribution (by laser diffraction).”^[3]

It also drew a line around one format. “In view of the limited available information on inhalation toxicity, which indicates severe inflammatory effects of microfine MBBT in the respiratory tract, caution is warranted against the use of the material in applications that could lead to exposure of the consumer’s lungs by inhalation”, and the opinion states plainly that it “does not apply to such applications that might lead to exposure of the consumer’s lungs to MBBT nanoparticles by inhalation”.^[3] That sentence is worth reading as written. It is a scope limit on a 2015 EU committee opinion about a skin product, not a finding about any sunscreen you own, and it says nothing about the cream on your face. If you’re wondering about spray formats generally, our sun spray guide is the better place for that.

One more asymmetry appears in the label composition section of the Tinosorb M sheet, where BASF prints the EU version of the name as “Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (nano) (EU)”.^[2] The Tinosorb S sheet has no such variant.^[1]

Where can I actually buy each one? Tinosorb S vs M on three rulebooks

Short answer: Korea treats them identically, Japan does not, and the US has only just moved on one of them.

Korea first, because that’s the market these formulas are built for. We opened the current version of the MFDS regulation on cosmetic safety standards, notice 2026-19, and parsed its UV filter table by hand. Both filters are in it, both capped at 10 percent, and for both the remarks column is empty.

Row in the MFDS table[5]	Limit	Remarks column
메칠렌비스-벤조트리아졸릴테트라메칠부틸페놀 (CAS 103597-45-1, Tinosorb M)	10%	Empty
비스에칠헥실옥시페놀메톡시페닐트리아진 (CAS 187393-00-6, Tinosorb S)	10%	Empty
트리스-바이페닐 트라이아진 (CAS 31274-51-8, for contrast)	10%	Bans aerosols including pump sprays, and sets a nano particle size and purity condition

We’re showing the third row so you can see what a filled remarks column looks like in that table. What we can’t tell you from this document is whether Korea requires a nano descriptor on the label the way the EU does, because that would sit in a different regulation and we didn’t open it.

How we counted filters. We downloaded the notice as an HWPX file, 555,463 bytes, unpacked Contents/section0.xml, and read the third table element, which is the UV filter list. It holds 34 rows: one header and 33 below it. One of those 33 is a continuation line carrying a second CAS number for an isomer of the same entry, so the table names 32 ingredients, not 33.^[5]

Japan is where the two part company. The BASF sheets carry an approval status table, and in the Japan row Tinosorb S shows 3 and Tinosorb M shows 10, both as a percentage, with a footnote reading “Japan: limit except for cosmetics coming into contact with mucous membranes”.^[1][2] Same manufacturer, same table format, and the two numbers in that row are 3 and 10.

The US is the row that dates these sheets. Both of them print a dash for USA, and both were issued before 2020.^[1][2] The section of US law that governs which actives can use the sunscreen monograph route opens by naming its list: “The following provisions apply to sunscreen products containing aminobenzoic acid, avobenzone, cinoxate, dioxybenzone, ensulizole, homosalate, meradimate, octinoxate, octisalate, octocrylene, oxybenzone, padimate O, sulisobenzone, titanium dioxide, trolamine salicylate, or zinc oxide, alone or in combination.”^[6] That is 16 substances, and searching the full text of the section for bisoctrizole, for benzotriazole and for triazine returns nothing at all.

Then a June 2026 FDA final order added bemotrizinol, which is Tinosorb S, to the sunscreen monograph, the rulebook that lets a product skip its own drug application, and it takes effect on 9 August 2026. We’ve written that story twice already and won’t repeat it: the news explainer on the filter itself, and what actually changes on the effective date, including the conditions and the exclusivity period. What we can say from the documents we opened for this piece is narrower than a claim about that whole order: BASF’s release announcing the approval is about bemotrizinol, and it does not mention Tinosorb M anywhere.^[8]

Three limits on this comparison, stated before you carry it anywhere

First, we did not find a study that measured both filters side by side under one method, and we did not go looking for a verdict. Everything above compares two documents about two materials, which is a weaker thing than a head to head test.

Second, we could not open the FDA’s own reasoning about bisoctrizole. Three FDA and regulations.gov files we tried returned errors or stub responses rather than documents. So the only US statement in this piece is that the section’s list of 16 does not name it. No source we read tells us why, and absence from a list is not a finding about a substance.

Third, the two BASF sheets are dated 2018 and 2019. Their chemistry and their solubility figures are not the sort of thing that drifts, but their approval status tables clearly have, at least in the USA row. Where those tables matter we’ve said what document and what date they come from.

FAQ

Should I look for Tinosorb S or Tinosorb M when I’m buying a Korean sunscreen?

There is no right answer to pick, because the two do different jobs and a formula can use both. Tinosorb S dissolves into a formula’s oils, and its maker describes it as a stabilizer for less stable filters. Tinosorb M stays as suspended particles, and its maker describes it as boosting oil soluble filters by scattering. Tinosorb M is the one to try on your own skin first if you care about a finish with no cast at all, and our no white cast piece works through why.

How do I tell which one is stronger?

You can’t, from these documents, and neither can we. We didn’t find anyone who has measured the two against each other under a single method. BASF calls Tinosorb S “the most efficient oil soluble broad-spectrum UV filter”, which is the manufacturer’s own wording and is limited to oil soluble filters. Its Tinosorb M page claims a strong contribution to UVA protection. Those are two claims by the same company about two products, not a ranking.

Why do I keep reading that Tinosorb M is water soluble?

Because it is sold as a water based liquid, so the shorthand is easy to reach for. The molecule itself is close to insoluble in water. The EU committee file lists “extremely low solubility in water (< 5 ng/L at 25 °C)” and its calculated log Pow, a number for how a substance splits between oil and water, as 12.7, with a committee note that log Pow “does not apply to insoluble particles”. What you buy is a dispersion, which means particles held in water rather than dissolved in it.

Can I get a US sunscreen with either of these?

For Tinosorb S the monograph route opens on 9 August 2026 under the June 2026 FDA final order, which also limits who may sell under it for a period, so read our effective date piece before assuming it will be everywhere. For Tinosorb M, the US permitted list in 21 CFR 201.327 does not name it, and BASF’s release announcing the bemotrizinol approval does not mention Tinosorb M anywhere. We have not read the order itself, so that is as far as we will take it.

Am I supposed to worry about the inhalation warning on Tinosorb M?

The wording is worth reading in full rather than in summary. A 2015 EU committee opinion said “caution is warranted against the use of the material in applications that could lead to exposure of the consumer’s lungs by inhalation” and set its own scope to exclude such applications. That is a statement about what the committee did and did not assess in products that could be inhaled. The same opinion concluded that the material at up to 10 percent in dermally applied products “is considered to not pose a risk of adverse effects in humans after application on healthy, intact skin”. We’re not going to invent a consumer instruction that the opinion doesn’t contain.

Sources

Manufacturer technical data, read in full on 2026-07-30:
[1] BASF, Technical Information Tinosorb® S, PRD 30481068, WF-No. 15794, Revision 1.0, valid since 02.08.2018, 6 pages. Source for the INCI name Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine, the physical form “Light yellow powder”, 628 g/mol, CAS 187393-00-6, the Application paragraph quoted here, the quality control absorption check in 2-propanol at 341 nm, the 100 percent content line with “Bemotrizinol (US)”, the solubility table read in table mode (17.0 percent in ethylhexyl methoxycinnamate down to “< 0.5” in ethanol) and the approval status table showing Korea 10, Japan 3 and a dash for USA: link
[2] BASF, Technical Information Tinosorb® M, PRD 30482916, Revision 1.1, valid since 12.03.2019, 6 pages. Source for the five part INCI name, the chemical description as an aqueous dispersion, the physical form “White liquid”, 659 g/mol, CAS 103597-45-1, the Application paragraph quoted here, the quality control absorbance check in DMA and IPA at 346 nm, the label composition read in table mode (48.0 to 52.0 percent active, 36.9 to 45.7 percent water, decyl glucoside 6.0 to 10.0 percent) including the EU name variant with (nano), and the approval status table showing Korea 10, Japan 10 and a dash for USA: link

European committee opinions, read in full on 2026-07-30:
[3] Scientific Committee on Consumer Safety, SCCS/1546/15, Opinion on 2,2′-Methylene-bis-(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol) (nano form), Submission III, COLIPA n° S79, adopted 25 March 2015, Revision of 25 June 2015, 83 pages. Source for the water solubility figure, the log Pow of 12.7 and the committee note that it does not apply to insoluble particles, the measured d(0.5) of 150 ± 9 nm, section 3.1.12 on UV absorption reporting Herzog and colleagues in Chimia 58: 554-559 (the 305 nm band, the shift of the longer band to 360 nm with a shoulder at 380 nm, the 320 nm shoulder, the particle size dependence and the 90 percent claim), the committee’s own challenge to that claim, and the conclusion with its particle size specification and inhalation caution: link
[4] Scientific Committee on Cosmetic Products and Non-Food Products intended for Consumers, SCCNFP/0082/98, Opinion concerning 2,4-bis-{[4-(2-ethyl-hexyloxy)-2-hydroxy]-phenyl}-6-(4-methoxyphenyl)-(1,3,5)-triazine, Colipa n° S81, adopted by the plenary session of 17 February 1999, 3 pages. Source for the maximum 10 percent opinion, the sentence proposing no further restrictions or conditions, and the percutaneous absorption line: link

Regulations, read in the original on 2026-07-30:
[5] Korea Ministry of Food and Drug Safety, Regulation on Safety Standards for Cosmetics, notice 2026-19, Appendix 2 (UV filtering ingredients). Downloaded as an HWPX file of 555,463 bytes from the ministry’s notice board and parsed directly from Contents/section0.xml, third table element: 34 rows, one header and 33 below, naming 32 ingredients because one row is a continuation line holding a second CAS number for an isomer of the entry above it. Methylene bis-benzotriazolyl tetramethylbutylphenol and bis-ethylhexyloxyphenol methoxyphenyl triazine are both listed at 10 percent with an empty remarks column, while tris-biphenyl triazine carries aerosol and nano conditions: link
[6] US Code of Federal Regulations, 21 CFR 201.327, Over-the-counter sunscreen drug products; required labeling based on effectiveness testing, retrieved from the eCFR versioner interface at issue date 2026-07-27. Source for the opening list of 16 substances quoted here, and for the search result that bisoctrizole, benzotriazole and triazine appear nowhere in the section: link

Peer-reviewed and company statements:
[7] Chatelain E, Gabard B, “Photostabilization of butyl methoxydibenzoylmethane (Avobenzone) and ethylhexyl methoxycinnamate by bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), a new UV broadband filter,” Photochemistry and Photobiology, 2001 Sep;74(3):401-6, PMID 11594052. Abstract read in full. Tested in oil in water sunscreen formulations under an optically filtered xenon arc source at one mean effective dose per minute; source for the concentration-dependent prevention of avobenzone photodegradation up to 30 MED and for the ethylhexyl methoxycinnamate result: link
[8] BASF news release, “Bemotrizinol, marketed by BASF as Tinosorb S, receives regulatory approval in the United States as the first new sunscreen active ingredient approved by the FDA since 1999,” Trade News, June 12, 2026. Source for the approximately 310 nm and 340 nm absorption peaks and for the description of Tinosorb S as a photostabilizer for more photo-unstable filters. Tinosorb M is not mentioned anywhere in the release: link

Topics: Bemotrizinol · Regulation & Labels · SPF Powder · Tinosorb · All topics