Mineral means natural and safe; chemical means industrial and suspicious. This equation comes up constantly, but what is the reality? In terms of both safety and effectiveness, the two families of filters are on par. Here is why the mineral vs. chemical filter opposition deserves more nuance before choosing the best daily sunscreen for your skin.
Mineral filters: how they work, benefits and limitations
Mineral filters (zinc oxide and titanium dioxide) are fine particles that sit on the surface of the skin without penetrating it, creating a shield effect. Remaining on the surface, these particles act primarily by reflecting and scattering the sun's rays, like mirrors, while also absorbing some of the light energy.
Benefits: very good skin tolerance, suitable for sensitive or reactive skin, and for children. Photostable, they do not degrade in the sun.
Limitations: without a tint, they can leave a white cast, especially visible on medium and dark skin tones. This whitish veil is explained by the size of the zinc oxide and titanium dioxide particles, which also diffuse a portion of visible light rather than just UV rays, hence this "ashen" effect that many people affected know well.
Chemical filters: how they work, benefits, limitations
Chemical filters (sometimes called organic filters) act differently: they absorb the energy of UV rays and dissipate it primarily in the form of heat.
Benefits: generally lighter formulas, with no white cast, that easily integrate into a morning routine—a real asset for consistency of application, the most decisive factor in the actual effectiveness of sun protection throughout the day.
Limitations: some chemical filters (avobenzone, octocrylene, homosalate...) are found in the blood at levels that exceed the threshold set by the FDA: a threshold that triggers additional studies, not a danger alert. It is precisely for this type of monitored molecule that Substance Of Light ® applies a strict blacklist, excluding from its formulas any substance subject to documented scientific doubt. We detail this selection on our Blacklist page.
How to identify the type of filter on the label
To know if a sunscreen uses mineral, chemical, or a combination of both filters, simply read the INCI list on the back of the product:
- Mineral filters: Zinc Oxide, Titanium Dioxide.
- Common chemical filters: Avobenzone, Octocrylene, Homosalate, Octisalate, Ethylhexyl Salicylate, Butyl Methoxydibenzoylmethane.
Many formulas today combine the two families to combine their respective qualities: light texture and broad-spectrum protection.
Does the type of filter change the sun protection factor (SPF)?
This is a common point of confusion: the SPF (protection factor against UVB) and the PA index (protection against UVA) do not depend on the filter family chosen, but on its concentration and the overall formulation of the product. A mineral SPF50 and a chemical SPF50 offer, by definition, an equivalent level of UVB protection according to regulatory tests; therefore, the mineral vs. chemical filter debate is not about measured effectiveness, but about texture and tolerance.
In practice, what makes the actual protection vary throughout the day is primarily the amount applied and the frequency of reapplication. A parameter that is identical for both types of filters.
Controversial filters exist in both families
This is the most misunderstood point of the mineral vs. chemical filter debate: the controversy does not follow a mineral/chemical divide; it spans both families.
On the mineral side: it is primarily the nanometric forms of zinc oxide and titanium dioxide that are subject to vigilance.
On the chemical side: certain specific molecules: oxybenzone, octinoxate, homosalate in particular, concentrate the majority of concerns, whether environmental (toxicity to corals) or related to skin absorption.
In other words, opposing "mineral" and "chemical" as a whole makes no scientific sense: the right question is not the family, but the specific molecule used in the formula.
Our approach at SOL®: transparency rather than dogma
We are convinced that the formula of a sunscreen depends on the rigor of the selected filters. This conviction has guided the development of the TRUE FILTER™ complex: more than three years of research, conducted with scientists and dermatologists. The result is based on four new-generation broad-spectrum (UVA and UVB) UV filters, present in the SPF50 PA++++ Moisturizing Fluid as well as in lhe SPF25 PA+++ Urban Protective Mist, and supplemented by protection against blue light and urban pollution.
This conviction is also reflected in what we refuse to use. Our selection explicitly excludes the most controversial filters on the market, such as oxybenzone, octinoxate, octisalate, octocrylene, avobenzone, homosalate, and PABA, as well as titanium dioxide and any nanometric form. Not out of a principle against a family of filters, but because each of these molecules has, in one way or another, a documented scientific doubt hanging over it. This selection, filter by filter, is documented on our Science page dedicated to the TRUE FILTER™ complex and on our Blacklist page, the strictest on the market on this subject.
FAQ
Which UV filters are used at Substance Of Light? Substance Of Light formulas are based on the TRUE FILTER™ complex: four new-generation broad-spectrum UV filters, covering both UVA and UVB rays, supplemented by protection against blue light and urban pollution. This complex is present in the SPF50 PA++++ Moisturizing Fluid and in the SPF25 PA+++ Urban Protective Mist.
Which UV filters does Substance Of Light exclude from its formulas? Our blacklist explicitly rules out oxybenzone, octinoxate, octisalate, octocrylene, avobenzone, homosalate, and PABA, as well as titanium dioxide and nanoparticles. This selection, filter by filter, is detailed on our Blacklist page.
Are mineral filters more "natural" than chemical filters? The term "natural" is misleading: zinc oxide and titanium dioxide are minerals processed industrially to become usable UV filters, just as chemical filters are manufactured using regulated processes. Neither of the two families is simply "extracted from nature" in its final form.
Bibliography
- Matta MK, Zusterzeel R, Pilli NR, et al. Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA, 2019. https://pubmed.ncbi.nlm.nih.gov/31058986/
- Downs CA, Kramarsky-Winter E, Segal R, et al. Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone on Coral Planulae... Archives of Environmental Contamination and Toxicology, 2016. Phttps://pubmed.ncbi.nlm.nih.gov/26487337/
- Vuckovic D, Tinoco AI, Ling L, et al. Conversion of oxybenzone sunscreen to phototoxic glycosyl esters by sea anemones and corals. Science, 2022. https://www.science.org/doi/10.1126/science.abn2600
