6.1 Introduction

Coatings and finishes are composed of film-forming resins, pigments, solvents, and additives.1 Although their existence predates plastics by several millennia, it is important to note that the resins used in modern coatings and finishes are the same as those used in plastics. For example, looking back to the 1930s, linseed-oil-impregnated webs called, oil cloth, were used in home decorating. They were also used to make floor coverings. At the same time, Linseed oil was the main resin used in industrial and trade sales paints. Today, vinyl resins have replaced linseed oil in decorative cloth, floor coverings, and many paints.

After coatings and finishes are applied, they form films and cure. Curing mechanisms can be as simple as solvent evaporation or as complicated as free-radical polymerization. Basically, coatings and finishes can be classified as baking or air drying, which usually means room-temperature curing. The curing method and times are important in coating selection, because they must be considered for optimizing equipment and production schedule choices.

Coatings and finishes today are engineering materials. They evolved from cave dwellers decorating their walls with earth pigments ground in egg whites into factory workers protecting products with E-coat primers and urethane acrylic enamels. Unlike Noah (who received divine instructions to paint his ark with pitch), the Egyptians (who mixed amber with oils to make decorative varnishes), or the Romans (who mixed white lead with amber and with pitch), scientists and engineers using plastic resins today...