Why is titanium dioxide widely used as a white pigment in paints and coatings?

Titanium dioxide (${\text{TiO}}_2$) is the most widely used white pigment in paints and coatings primarily due to its exceptionally high refractive index, which allows it to scatter light efficiently.1

Specifically, the rutile crystal form of ${\text{TiO}}_2$ possesses a refractive index of 2.76, the highest of any material that can be manufactured as a pigment at a reasonable cost. This high refractive index enables the pigment to scatter all wavelengths of visible light, creating the perception of whiteness and providing superior opacity, or "hiding power," which prevents light from penetrating through a paint film to the underlying substrate.1

Beyond its optical efficiency, rutile ${\text{TiO}}_2$ is preferred for exterior applications because it offers greater durability against environmental exposure compared to other forms like anatase. Because of these properties, it has largely replaced older, less efficient, and toxic pigments such as white lead. While the vast majority of titanium mineral consumption is dedicated to the pigment industry, it remains a vital material for achieving brightness and opacity in a wide range of commercial products.123