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How Low-VOC Paint Works

Paint Components: Dissecting the Grass Green Paint on Your Walls

As you apply the second or third coat of paint to your do-it-yourself project, you're probably thinking more about how tired you are than about what's in the paint. But the paint's composition actually has a lot to do with how many coats of it you'll need.

Paint is typically made of three major components:

  1. Pigment: gives the paint its color
  2. Binders: also known as the vehicle or medium, binders help the pigment stick to the applied surface.
  3. Solvents: sometimes called carrier or thinner, keep the paint in liquid form, making it easier to apply.

Of these three components, the solvents contribute the most to the paint's level of VOCs. That's because the solvent (a liquid) is designed to evaporate quickly, leaving only the pigment and its binder (the solids) behind on your walls. Paints with a greater percentage of solids typically leave more pigment behind, thus requiring fewer applications.

VOCs coming from a paint can and paintbrush
The VOCs in paint rapidly vaporize and enter the air, contributing to ozone pollution and health problems.

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Solvents tend to be either oil-based (high VOC content) or water-based (low or no VOC content). Latex paint, which has lower VOC levels and is generally more environmentally friendly than oil-based paints, uses water-based solvents.

Common oil-based solvents include white spirit, formaldehyde and toluene, along with a variety of other alcohols, ketones, acetates and aromatic compounds. Before volatile solvents like these were introduced to painting, oil paints were difficult to apply and rarely used. Now they're being phased out again as environmental and health concerns trump their convenience.

Taking the High Road
Despite their bad rap, automakers occasionally get something right. In this instance, it's Toyota, Ford, Mazda and General Motors who score a few green points by turning to more environmentally friendly painting methods. To reduce the amount of VOCs associated with producing each new car, the manufacturers now use water-borne paints instead of solvent paints [source: Richard]. Ford also is using more environmentally friendly chemicals in its paints [source: Arellano]. The low-VOC paints aren't yet used on all car coatings, and of course this does nothing to reduce the massive amounts of VOCs emitted by driving the car, but every little bit helps.

Replacing the oil-based solvent doesn't rid a paint of harmful chemicals entirely, though. Pigments and binders may also contain VOCs, and all three components often contain a range of other toxins. For example, cadmium and chromium -- dangerous metals regulated by the U.S. Environmental Protection Agency -- are sometimes used in pigments. In addition, some paints include toxic materials to prevent mold growth or extend shelf life.

While a low-VOC label on paint indicates only that it's lower in VOCs than traditional paints, some paints eliminate the other toxins as well. Learn more about the low-VOC designation and other environmentally friendly alternatives on the next page.