There are basically two types of paint: acrylic latex paint, often simply called latex paint, and oil-based, or alkyd, paint. Acrylic latex paint is essentially a paint made with water and an acrylic resin binder. Oil-based paint most often uses a hydrocarbon-based solvent as the “vehicle” and an alkyd resin.
All paints are composed of a solid, or binder, and a vehicle. Acrylic latex paint uses the acrylic resin as the binder and water as the vehicle. The binder will hold together the various pigments and the water to form the film that covers the painting surface. Binders are the major components that provide the paint with its application properties.
Acrylic latex paint, often advertised as 100% acrylic latex, is one of a number of water-based paints, and it is generally considered the highest-quality latex paint. Other resins used in this paint include styrene, epoxy, and polyvinyl acetate. Of the paints available, vinyl acrylic latex is the most popular.
The acrylic used as the binder is a type of synthetic polymer, or plastic. There are a number of synthetic polymers that are used for a variety of applications. Latex paints, however, use only one, called an elastomer. As the name implies, elastomers are quite flexible — or elastic — and thus give these paints their advantageous dry flexibility.
Latex paint, especially acrylic latex, has a number of advantages over oil-based paint. Application advantages include superior adhesion, flexibility, breathability, washability, opacity, and color-retention. In addition, the painting equipment (brushes, sprayers, etc.) used to apply the paint can be easily cleaned with plain water and, if needed, a mild detergent. This eliminates the expense and volatility of the cleaning solvents needed to clean the application equipment used for alkyd paint.
There are, of course, some limitations to latex paint. These include its poor adherence to glossy or shiny surfaces, and its unsuitability for unprimed steel, where the water-based nature of the paint might cause rust. Unless specially formulated, latex paint will also raise the grain on wood that is not primed.