Waxes can be defined as "hydrocarbons or hydrocarbon derivatives that are solid at room temperature, but are lowviscosity liquids at moderate temperatures." Waxes are thermoplastic materials, but due to their low molecular weight, they are normally not considered to be plastics or polymers. Common wax properties are: water repellency, smooth texture, low toxicity, low odor, combustibility, solubility in most organic solvents, insolubility in water, and low reactivity. By far the most important waxes in terms of volume produced and economic impact are petroleum waxes. Petroleum waxes are derived from crude oil. Other types of wax include: animal waxes, such as beeswax; vegetable waxes such as carnauba, candilla, and soy; mineral waxes such as montan; and synthetic waxes such as Fischer-Tropsch and polyethylene. Although this chapter deals only with petroleum waxes, much of the information and many of the test procedures can be applied to other types of wax as well.