The Effect of Fine-Particle-Size Extenders and Entrapped Air on TiO2 in Emulsion Paints
It is true to say that, over a period of 30 or so years, paint formulators have made use of smaller-particle-size extenders in their paints and significantly reduced their TiO2 content. For example, a typical high-quality matte paint of the 1970s would often contain in excess of 18% by volume TiO2. Through use of small-size calcined clay extenders, and to some degree opaque polymers, this level has now been reduced to typically between 10 and 14% by volume.
It is difficult to see how modern paints, with the already reduced TiO2 volume concentrations (vc), could continue to benefit from extender manufacturers' continuing claims of potential savings of 20 to 30% TiO2 by using their fine-particle-size extenders.