Recent analyses of food-grade TiO₂ samples have found that a significant portion of particles may be within the nanoscale. These particles (also known as nanoparticles) range in size from 1 to 100 nm, where 1 nm equals 1 billionth of a metre (the width of a typical human hair is 80,000 to 100,000 nm).

Zinc oxide. Zinc oxide is a popular cross-linking agent for rubber and for various resins. It is essential in the formulation of solvent-borne polychloroprene adhesives. Furthermore, zinc oxide is a good UV stabilizer, has biocidal activity and has a relatively high refractive index (2.0) which makes it an efficient white pigment. Some typical properties are: density 5.6 g/cm³; particle size 0.036-3 μm; oil absorption 10–20 g/100 g; specific surface area 10–45 m²/g. Zinc oxide is produced by reaction of the metal in the vapour state with oxygen. Zinc oxide is nonporous and is quite pure. Thus, the high surface area of some grades is due to the small particle size of zinc oxide. Some grades, especially for use in the rubber industry, are surface modified by deposition of 0.2-0.4% of stearic acid, propionic acid, or light oil [47].