Reducing the Cost of White Opacity Optimized Use of Titanium Dioxide

By Alan Smith

Titanium dioxide (TiO₂) is a key element for creating whiteness and opacity in paints and coatings. Since 2008, TiO₂ costs have risen more than 70%, and current prices now exceed $1.70 per pound. As a result, paint manufacturers are reviewing their technology options to identify opportunities to reduce TiO₂ consumption. This is particularly true in the architectural coatings segment where TiO₂ is the largest component of raw materials costs. How can paint manufacturers leverage this broad technology base to help them reduce the cost of whiteness and opacity?

Before we can answer this, it is important to first understand how TiO₂ works. Opacity, or hiding power, is the ability of a paint film to hide a substrate.¹ At complete opacity, the reflected light will not recognize the substrate underneath the paint film. Dark colored paints achieve opacity by light absorption of colored or black pigments. The principal factor that determines the opacity of a white paint film is light scattering efficiency.

Scattering is a measure of light interaction with the pigment particles suspended in a polymer matrix. The magnitude of the interaction of the light with the suspended particles determines the hiding power of the paint film. The scattering efficiency is determined by two factors: refraction and diffraction of light.