When choosing paint, often the most perplexing question for homeowners is whether to choose latex or oil/alkyd. This confusion is rooted in history. For years, solvent-based paints were favored for woodwork, trim, and some interior and most exterior surfaces because they flow uniformly, have excellent leveling characteristics, adhere well- particularly to chalky or poorly prepared surfaces-and provide a tough, hard-shell finish. In addition, exterior alkyds can be used in sub-freezing climates.
But now, change is in the wind-literally. Both state and federal air-quality laws are clamping down on the use of solvents in oil/alkyd paints. The problem is this: A gallon of solvent-based paint contains about 2 quarts of mineral spirits. These solvents evaporate into the air as volatile organic compounds (VOCs), causing pollution.
In the near future, the Environmental Protection Agency (EPA) is expected to issue guidelines to all states, setting minimum standards for paint formulas. Many existing state regulations already align with or exceed the expected standards. Some states, such as California, already have more stringent requirements.
These guidelines significantly affect the makeup of solvent-based paints. Solvent paints that comply with these guidelines don’t have any advantages over water-based paints. In fact, they dry slower, are more difficult to apply, and cost more. Although water-based paints contain various levels of the regulated solvents (in an “alkyd-modified” latex, there may be as much as 1 pint of solvent per gallon), solvent levels in all water-based paints fall far under the limits.
These new regulations are good news for most people. The environmental constraints have forced better technology than ever before, and the new water-based finishes are more varied and outstanding than even five years ago. A good-quality acrylic latex has far better gloss retention and fade resistance than an alkyd. It can be used on aluminum siding or vinyl siding, as long as a paler shade is chosen (darker colors absorb heat more, and heat may distort the siding).
The only place really left for alkyds is trim, the front door, and maybe the windows. If there’s an older coating of oil/alkyd paint and the finish is flaking or poorly prepared, it may be smart to seek out an oil/alkyd paint that complies with regulations. But judging by the tightening standards, there may come a day when all paints are required to be 0 VOC.
The bottom line is this: The technology has shifted so dramatically that your best choice in most situations will be latex paint. Eventually, latex may become your only choice.
Latex paints are not all the same. Although the first latex paints were named after their synthetic “latex” rubber base, synthetic rubber isn’t used anymore. Now the term “latex” encompasses all water-borne paint. But within that category, there are choices, notably vinyl-acrylic, 100% acrylic, and alkyd-modified latex.
Vinyl-acrylic latex is the least expensive, suitable for most interior walls. High- performance interior paints are 100% acrylic; they have better color retention, better adhesion, and, in the case of the enamels, better gloss than vinyl-acrylics.
High-quality exterior paints are either 100% acrylic or alkyd-modified latex. Both are excellent. If the siding was previously painted with an alkyd or is chalking, consider using an alkyd-modified latex, which does a better job of penetrating and anchoring the coating on a chalky surface.
Alkyd paints come in enamel and what is most commonly referred to as house paint.
Enamel, available in a wide variety of colors that are ready to mix, may be used on any kind of surface but is especially suitable for highly trafficked areas that require a hard, nonporous finish, such as doors and trim.
House paint is more versatile than enamel but also more problematic. Its VOC content makes it a better candidate for exterior painting, though several states have banned it because of air-quality regulations. In states where it is available, it generally only comes in quart cans, meaning it is an expensive choice for siding.
Alkyd paint is vastly preferred over latex paint for surfaces that are glossy or to which latex has trouble adhering. In addition, alkyds dry at a slower rate than latex, allowing brush and roller marks time to smooth out. However, this also means that if the paint is applied too thickly, it will sag.