Zinc oxide is an inorganic compound formed from a combination of one molecule of the mineral zinc and one molecule of oxygen. Zinc is one of the most abundant elements on the Earth and is a silver-colored metal with a medium luster. When the metal combines with oxygen, it forms a white powder that slightly resembles flour or baking soda. Since natural zinc oxide is quite rare and commercially unavailable, they are widely used through synthetic process. Zinc Oxide was used as a good, strong white pigment since the mid-1800s.
Three different processes are used for manufacture of zinc oxide: 2 are thermal processes and 1 wet chemical process. One thermal process begins from metallic zinc, the other from oxidic zinc residues or ores. In both processes, zinc vapor is generated and burned to zinc oxide. In the wet chemical process, zinc is leached from zinc containing raw materials and then precipitated as zinc hydroxide/-carbonate. The precipitate is calcinated to zinc oxide, ZnO.
Paint & Coatings Industry: Zinc oxide is a component in many productions of durables and protective paints. One of its essential properties is its opacity to ultraviolet light in the finished coatings, which improves weatherability. It also protects the paint film from mildew, enhances resistance to abrasion and neutralizes the harmful acids formed by vehicle aging.
Rubber Industry: Zinc oxide along with stearic acid is used in the vulcanization of rubber. ZnO additive also protect rubber from fungi (see medical applications) and UV light.
Ceramic Industry: The relatively high heat capacity, thermal conductivity and high temperature stability of ZnO coupled with a comparatively low coefficient of expansion are desirable properties in the production of ceramics. ZnO affects the melting point and optical properties of the glazes, enamels, and ceramic formulations.
Pharmaceutical Industry: Zinc oxide as a mixture with about 0.5% iron(III) oxide (Fe2O3) is called calamine and is used in calamine lotion. There are also two minerals, zincite and hemimorphite, which have been historically called calamine. When mixed with eugenol, a ligand, zinc oxide eugenol is formed, which has applications as a restorative and prosthodontic in dentistry.
Other Applications: Zinc oxide is even used in food manufacturing as an additive for many food products including breakfast cereals, as a source of zinc, a necessary nutrient. Some pre-packaged foods also include trace amounts of ZnO even if it is not intended as a nutrient.