Scientists Solve Mineral Sunscreen's White Cast Problem

Millions of people who avoid mineral sunscreen because of its chalky white residue just got some great news from scientists at UCLA.

Researchers developed a new shape for zinc oxide nanoparticles that prevents the annoying white cast mineral sunscreens leave on skin. The breakthrough could help more people protect themselves from skin cancer, the most preventable cancer in the United States.

The secret lies in transforming traditional round zinc oxide particles into four-armed structures called tetrapods. These tiny star-shaped particles naturally resist clumping together, which means no more white streaks when you apply sunscreen.

Lead researcher Ajoa Addae, a UCLA doctoral candidate, started the project because of her own frustration. "I was frustrated by how mineral sunscreen looks on my own skin," she said, adding that the white cast problem sometimes led her to skip sunscreen altogether.

The team used flame synthesis, heating zinc with ethanol in a furnace to create the special four-armed shape. When they tested the new particles under an electron microscope, they discovered something exciting: the arms act like standoffs that keep particles evenly distributed instead of collapsing into clumps.

The new formula produces a warmer color that better matches different skin tones. Even better, the particles stay stable longer on the shelf, solving another common problem with mineral sunscreens that often separate or streak over time.

Chemical sunscreens absorb into skin and don't leave a cast, but many people prefer mineral options that sit on top of the skin as a physical barrier. Until now, that preference came with a cosmetic cost that discouraged daily use.

The research team confirmed that changing the particle shape doesn't reduce protection. The tetrapod sunscreen still blocks both UVA and UVB rays just as effectively as traditional formulas.

Why This Inspires

This discovery shows how personal frustration can spark solutions that help everyone. Addae turned her own daily annoyance into groundbreaking research that could change how millions of people approach sun protection.

Dermatologists recommend daily sunscreen use to prevent skin cancer, but cosmetic concerns have been a real barrier. When sunscreen looks better on skin, more people actually use it, which means better health outcomes for communities of all skin tones.

The flame synthesis method the team used is relatively simple, suggesting manufacturers could adopt it without major production overhauls. That means this innovation could reach store shelves faster than more complex formulation changes.

Better sunscreen that people actually want to wear could save lives.