Classifications

There are different ways to classify paints and coatings. The most common system for architectural and industrial paints is classification based on the vehicles or binders used in the paints. There are four categories in this system including alkyd, latex, epoxy, and urethane. Alkyd paints are driven from combination of an oil acid with alcohol. Latex paints are emulsion of acrylic or vinyl acrylic synthetic resins and pigments kept in water. Epoxy paints and urethane paints are driven from an epoxy resin and urethane resins, respectively.

Manufacturers have another common system for classification of coatings in which the function and end use of coating is considered. These classifications are:

• Primers/undercoats
• Tie coats
• Finish coats
• Sealers
• Shellacs, varnishes, and lacquers
• Stains
• Special purpose coatings

Primers are the first layer of coating in a multi-coat system. They provide adhesion and protect the substrate. Tie coats are a transition from a primer or undercoat to a finish coat. A finish coat, or top coat, is the last layer of coating applied in a multi-coat system. They provide the desired appearance as well as protect primed substrate from abrasion, heat, cold, sunlight, moisture, water immersion, or damaging chemicals. In some cases, sealers are applied before the primer in a porous surface. Shellacs, varnishes, and lacquers are usually applied to provide finish look for furniture and interior surfaces. Stains are applied before varnishes to provide better appearance and clear finish. Finally, there are many special purpose coatings made for specific applications. Some of these include fillers, texture coatings, elastomeric coatings, dry, fall/fog coatings, floor coatings, fire-retardant/high heat-resistant coatings, and encapsulants.