The importance of coatings has increased hugely during the modern era of technology. Coating is defined as a material (usually a liquid) which is applied onto a surface and appears as either a continuous or discontinuous film after drying. Coatings are mainly applied on surfaces for decorative, protective or functional purposes but in most cases it is a combination of these. The properties of coating films are determined by the types of binders, pigments and miscellaneous additives used in the formulation. The terms "coating" will be used synonymously in this book. In general, collectively or individually, paints, varnishes and lacquers are termed as coating.