The white cast from sunscreen is familiar to many. Image: New Atlas
Zinc oxide is one of the most reliable UV filters: it simultaneously blocks both UVA and UVB rays, doesn’t break down under sunlight, and is well-tolerated by the skin. The only problem is that when applied, it leaves a noticeable white or gray cast, which causes many people, especially those with darker skin tones, to forgo such protection altogether. But it turns out you don’t necessarily have to use that kind of cream. A new study has helped create a sunscreen that doesn’t leave such marks, meaning everyone can use it to protect their skin.
Why Sunscreen Leaves a White Cast on Skin
Traditional zinc oxide particles have a rounded shape resembling blood platelets and tend to clump together. When they gather into clusters, they begin scattering visible light — this is exactly what creates the infamous white or grayish tint on the skin. The darker the skin tone, the more contrasting and noticeable this effect becomes.
Researchers at the University of California, Los Angeles found a way to fix this without changing the chemical composition — only the shape of the particles. The study’s first author, AJ Addai, a U.S. citizen of Ghanaian descent, admitted that the problem affected her personally. She said she started thinking about it because she was frustrated by how her skin looked after applying sunscreen to her dark skin.
Instead of developing a new chemical compound, the UCLA team focused on changing the geometry of the particles using a flame synthesis method. The source material containing zinc ions was heated to 900 degrees Celsius. At this point, the particles evaporated and broke apart, and upon cooling, they bonded with oxygen to form zinc oxide crystals. The key difference — the crystals took on a tetrapod shape: four “legs” extending from a central node.
AJ Addai — the study’s author. Image: New Atlas
This shape fundamentally changes how the particles behave in the formula. Due to their structure, tetrapod particles form porous networks instead of clumping together. They cannot pack tightly and therefore distribute evenly in the cream. Even distribution means no light-scattering clusters, and consequently, minimal white cast.
New Sunscreen for Sun Protection
The new sunscreen received an SPF 30 rating — a sufficient level of protection by dermatologists’ standards. A series of color science tests confirmed a significant reduction in white cast, and the study author’s personal experience served as convincing practical proof that such a simple and familiar product can be made much better.
The team is currently collaborating with UCLA Health’s Skin of Color Clinic to study the effects of the new ZnO particles on the skin microbiome — a necessary step before mass production of the product can begin. If the development passes all verification stages, the market could see a mineral sunscreen that works equally well on any skin tone — without compromising between protection and appearance.
