Zinc oxide has long been considered one of the most effective ingredients for sun protection, as it can block both UVB and UVA rays. However, its thick white residue left on the skin after application is far from popular—except perhaps among lifeguards on 1980s beaches. Researchers at UCLA believe they have found a way to solve this aesthetic issue.

Why People Avoid Zinc Oxide Sunscreens

The chalky white film left by some sunscreens is one of the main reasons many people choose not to use them. After all, when you want to show off your summer tan, the last thing you want is to look like you spent the whole season in a basement. Nevertheless, regular use of sunscreen is one of the most effective ways to prevent skin cancer.

If it were possible to create a sunscreen that maintains its protective properties without making the skin look pale, far more people would use it. This idea inspired the UCLA team to search for a new solution.

"The best sunscreen is the one people will actually use," notes AJ Addae, the study’s lead author. "If we can make zinc oxide more aesthetically pleasing for different skin tones without sacrificing effectiveness, it will help more people protect themselves from the sun’s harmful effects."

A New Approach: Changing Particle Shape

Instead of developing a new chemical compound, the scientists decided to alter the shape of the particles in the already proven and safe zinc oxide (ZnO). Typically, ZnO particles in creams are round and tend to clump together, which scatters visible light and creates a white or gray cast—especially noticeable on darker skin.

The UCLA team used a flame synthesis method to change the particle shape. They heated a material containing Zn²⁺ ions to 900°C, causing the particles to evaporate and break apart. As the material cooled, free zinc combined with oxygen to form zinc oxide crystals. Importantly, these crystals took on a tetrapod shape—with four "arms" extending from a central node, resembling jacks from the classic children’s game. This structure prevents the particles from sticking together.

"Thanks to their structure, tetrapod particles form porous networks and don’t clump together," Addae explains. "They can’t pack tightly or aggregate, so they distribute evenly in the cream."

Results: Less White Cast, Same Protection

The new SPF 30 sunscreen, made with tetrapod-shaped ZnO particles, was found to be significantly less white—confirmed by various color analysis tests. Addae, an American of Ghanaian descent, immediately noticed the difference when she applied the cream to her own skin: the typical white residue of conventional zinc oxide products did not appear.

"When I put it on my skin, there was none of the white cast that usually comes with zinc oxide," Addae shares. "At that moment, I realized this could really work."

Personal Experience as Motivation

According to Addae, one of the main motivations for the study was her own experience with the appearance of traditional mineral sunscreens on her skin.

"I started thinking about this because I was frustrated by how mineral sunscreens looked on my skin," she says. "A lot of my motivation came from personal experience: I tried using mineral creams, but dealt with white residue and other aesthetic issues. Eventually, I just stopped using them. That frustration became the starting point for our work."

Next Steps

Currently, Addae’s team is collaborating with the Skin of Color clinic at UCLA Health to study how the new ZnO particles affect the skin’s microbiome. This is the first step toward creating a commercially viable product.

The study results have been published in ACS Materials Letters.