Researchers at the University of Michigan have introduced a new method to create vibrant structural colour coatings from unprocessed natural minerals. Their approach reduces material costs and makes the technology far more accessible for designers and manufacturers. The study, published in Optics and Photonics Research, offers fresh possibilities for architects, product designers, automotive designers and packaging professionals who work with durable and sustainable surface finishes.

Structural colours for long-lasting design

Structural colours do not rely on pigments. Instead, they appear when light interacts with thin stacked layers. This creates intense, stable colour effects that resist UV light, humidity, heat and chemicals. Because the colour does not fade, these coatings can offer durable alternatives for façades, interior surfaces, consumer products and even vehicle parts.

Despite their benefits, structural colours remain niche due to high production costs. Traditional methods require highly refined materials and complex deposition systems.

From raw minerals to optical coatings

The research team developed a simpler route. They used raw mineral powders such as silica, titanium dioxide, iron oxide and copper oxide. Electron beam evaporation allowed these minerals to form thin layers with the optical quality needed for structural colour.

During the process, the minerals naturally purified. Stones that contain impurities—like scoria or blue topaz—still produced clean silica-like layers. This behaviour results from the specific evaporation properties of silica.

To make the coatings suitable for common substrates, including glass and plastics, the team created a new absorber layer. A blend of copper oxide and iron oxide formed a stable film with metallic-like absorption. This layer helped generate a wide range of colours, including yellow, green and purple.

Scalable and more sustainable colour technology

Advanced tests confirmed that the colours produced by the mineral-based layers matched optical simulations. The method shows that natural mineral powders can deliver reliable, repeatable structural colours without expensive refined materials.

For designers, the technology offers a scalable and more sustainable way to work with colour. It reduces dependence on synthetic pigments and uses abundant, low-impact mineral sources. Possible applications include architectural panels, interior finishes, product housings, mobility components and packaging surfaces.

Source: EurekAlert! / Optics and Photonics Research (ELSP)
Photo: Couleur