A zinc oxide coating is a solution containing zinc oxide, which is an inorganic compound, generally as a means to prevent corrosion. An inorganic compound is a chemical mixture that does not contain carbon or organic chemicals. Zinc oxide paints or coatings are particularly useful for application to galvanized iron as a zinc oxide coating can remain on this kind of material for very long periods of time. This can be seen with items that are found in outdoor environments, such as nails or screws. Zinc oxide is a component of many other materials and tools, for example concrete, rubber, and many household objects.
Many paint formulas call for the addition of zinc oxide as an ingredient, particularly exterior paints that are used outdoors and constantly exposed to the elements. This kind of zinc oxide coating paint can also help in the absorption of sunlight, helping to prevent premature cracking or peeling on the painted surface. Indoor paints can benefit from the addition of zinc oxide as well, and white enamels often contain this compound to prevent yellowing.
Metal objects or structures often have a zinc oxide coating. Steel benefits from this as the coating can last for a very long time, protecting it from exterior conditions. Additionally, zinc oxide coatings can be used on steel that is underwater, such as a fresh water tank for fish or other sea life. Even very large steel objects that are underwater, such as those found in dams, can benefit from a zinc oxide coating.
Common household objects also benefit from having a zinc oxide coating. Items made out of ceramic or glass may be given such a coating in order to reduce thermal expansion so that a plate, mug or similar object will not crack as easily when exposed to high temperatures. Zinc oxide coatings are also often found on pottery as a protective glaze and objects made out of plastic may be given a zinc oxide coating to improve the object's tensile strength, heat resistance, and resistance to weather and sunlight.
Zinc oxide has a very extensive list of uses and applications in addition to being used as a direct coating. One example is in the rubber manufacturing process. Zinc oxide aids in the reinforcement of the rubber and is used as a bright white pigmentation. Furthermore, zinc oxide is also used to secure rubber to brass objects as it can interact with another compound, copper oxide. The two produce a zinc-copper salt and form a strong bond, holding the rubber to the brass.