We offer several grades of titanium dioxide, both anatase and rutile, for use in a variety of industries. Both rutile and anatase provide excellent opacification (hiding power) but have somewhat different characteristics. Anatase is less expensive, but rutile is slightly more efficient in some applications. This is due to the high refractive index of these crystal structures.
Anatase is an excellent choice for filling of paper. It is economical, easily dispersed in water based systems, and an excellent opacifier. Untreated anatase provides tio2 with a refractive index of 2. 55. This form is also good for use in interior paints, plastic filling, and highway marking paints. With the exception of highway paints, it is not recommended for exterior (weather exposed) paint applications.
Rutile provides superior "wet" opacity, which is useful in wet strength paper grades, waxed papers, and other saturated applications. It is slightly more efficient than anatase with a refractive index of 2. 70, but it is more expensive. Rutile is often provided as a "treated" product, which aids in easy dispersion in high solids coatings and in weather / fade resistance. Treated products often contain less than 90% actual tio2 with the balance being the "treatment". Rutile has superior weather resistant characteristics for applications with exterior (outdoor) exposure or where long term light fastness is important.
For filling applications in the paper industry, untreated rutile can offer a significant value advantage. It provides the efficient rutile crystal structure but without treatment, remains economical due to the high tio2 content. It is easy to see why titanium dioxide produces such superior hiding power when the light refraction data below is considered.