Categories of conventional paints

Conventional paints are commonly classified into two categories: water-based and oil-based . Oil-based paints are sometimes referred to as solvent-based. Paints consist of a resin or binder, pigments, and a carrier. They also consist of solvents, toxic metals, and volatile organic compounds (VOCs) that can cause smog, ozone depletion, and indoor air quality troubles with negative health effects. These unhealthy ingredients off gas into the air during the application and curing of paints, and even after the paints are dry.

Once paint is applied, the carrier evaporates leaving behind a solid coating. In oil-based paints the carrier is a solvent consisting of VOCs. Titanium dioxide, a pigment used in nearly all paint production, is manufactured using a extremely polluting and energy intensive process. It reacts with sunlight to donate to smog when used in exterior application, and poor indoor air quality when used in interior application. Fungicides and preservatives (collectively known as biocides) are added to latex paints to combat mildew.