Until the 1950s, oil paint was the most common kind used inside and outside the house. It worked well but was time-consuming to apply, took at least a day to dry, emitted strong odors, and had to be cleaned up with potent solvents. With the postwar housing boom, drywall replaced plaster and oil paints were bested by quick-drying formulas that could be cleaned up with soap and water. Today most coatings are water-based latex paint.

Paint’s many categories, types, and finishes are as hard to decode as abstract art (Is that Picasso’s wife or a bunch of squiggles?). You may come across claims that there’s one paint for molding and another for trim—even though they’re the same paint. Buzzwords like “infused cross linking” and “copolymer emulsion” make it tough to figure out what’s in the can and where to use it. Below are some key definitions and important points to consider when you select paint.

Alkyd (Oil-Based)

The modern version of oil-based paint is synthetic resin (alkyd). It’s tough, durable, washable, and often used for kitchens, baths, and woodwork. It produces a smooth finish and dries flat with few unsightly brushstroke marks, usually overnight. Alkyd cleans up with turpentine or mineral spirits. But because the use of oil-based paint has been restricted due to the amount of VOCs (volatile organic compounds) they contain, you probably won’t find anything but latex in stores.

Acrylic (Latex)

Acrylic is the water-based equivalent of alkyd—a synthetic latex paint. It’s also durable, and is the water-based formulation often recommended for high-use areas like kitchens and baths. It dries faster than oil-based paint, emits fewer odors, and contains smaller amounts of VOCs. But the main reason latex wins popularity contests is that the stuff cleans up with soap and water and is easy to apply. Plus, the resulting surfaces are scrubbable, chip-resistant, and retain color and sheen as they age. In indoor spaces, drying times are usually only a few hours.

Interior vs. Exterior

Interior and exterior paints are not interchangeable; they’re formulated differently. Generally, interior paints are made to dry harder than exterior paints, which makes them less flexible but more scrubbable. Outside, flexibility helps paint withstand extremes of weather. Also, additives used mostly in exterior paint improve resistance to mold formation and fading from sunlight.

A switch from oil-based to latex will require special preparations—coating an old oil-based paint with latex can cause the underlying layer to flake and lift, sometimes within a matter of hours. If you are switching from oil to latex, try a test-patch application of oil-based primer, let it dry at least 24 hours, then test a finish coat of latex. To discover what’s on the wall, clean and dry a sample spot and rub the area with a swab soaked in denatured alcohol. If the paint comes off, it’s water-based; if it doesn’t, it’s oil-based.


Flatter finishes conceal more defects, while glossier finishes highlight them. But flat finishes tend to look best on walls and ceilings, while glossier finishes look best on woodwork and are easier to clean. It sounds simple, but manufacturers use a bewildering array of words to describe the range. Although the best way to decide is to buy a pint and test it, here’s a rundown of the differences:

  • Flat or matte—reflects the least amount of light and gives a rich finish to deep colors.
  • Satin, silk, eggshell, or low-luster—has some shine and usually means the paint is more washable than flat/matte.
  • Semi-gloss—sometimes used on walls in kitchens and baths, but more often on woodwork and trim.
  • Gloss or high-gloss—highly reflective, can be glaring on trim next to a flat wall paint and nearly blinding in a brightly lit kitchen.


A figure for the square footage covered per gallon appears on the paint can, but it’s generally overly optimistic. Multiple calculators on the web can help you figure out how much to buy. In general, you’ll need one gallon per 300 to 400 square feet of surface.


You can obtain samples from stores, and on the web you’ll find online design programs (many from paint manufacturers) with palettes displaying millions of possible combinations. The trick is to translate the color you have in mind to the paint that finally appears on the wall. Swatches can help, as long as you try them in different light on different walls. But for large projects that can require several gallons, painting a small sample area is a wise move.

Paint Ratings

Consumer Reports regularly conducts accelerated aging and exposure tests on paints from many manufacturers in its unbiased ratings. Some of its top-rated products performed better than more expensive paints and cost $10 to $20 less per gallon.