By Janet Eastman
June 21, 2007
CARL MINCHEW is a paint nerd. While the rest of us walk into a room and instantly see radiant walls that pop or ho-hum coatings that sink into the background, he sees a complex recipe of binders, pigments, drying oils and surface active agents.
The director of color technology for Benjamin Moore can spot uneven microscopic surfaces and the way they monkey with paint and light. The right paint – thick, smooth and vibrant, he says, looks and even feels better. Good paint, of course, also doesn’t rub off when we wash the walls.
Minchew, who has been on the job for 34 years, says, “It is fun watching paint dry.”
OK, Paintdexter, you have our attention. Share with us your knowledge of the chemistry in a can of paint. But keep the science and lingo about “color uniformity” and “rheology enhancers” to a minimum. We’re artists, not eggheads.
* Types of paint: Oil-based paint sticks to difficult surfaces, has good leveling characteristics and its hard film resists abrasion and tackiness. It uses petroleum-derived hydrocarbon solvents and contains alkyd, a synthetic resin made with natural oil (such as linseed oil) that allows the liquid to spread easily, dry relatively fast and to be durable and resistant. But most oil-based paints lose their color over time, become brittle and may crack and flake.
Water-based (or latex) paint has a film formed by acrylic binders that don’t undergo chemical reactions as they dry. The acrylic particles draw together as the water evaporates, forming a stable yet flexible film that can expand and contract with the underlying wood. At the molecular level, this film resembles a fine mesh that’s loose enough to pass vapor but tight enough to shed liquid water. Acrylic paint also holds its color longer than alkyd and is less susceptible to cracking.
* Quality: High-end paint may cost more, but it generally has “better hiding,” that is, it creates a heavier film and covers the surface in one or two coats, obscuring whatever was underneath it. An expensive ingredient in the pigment – titanium dioxide – is needed to do this. Costlier paint is easier to apply, dries to a smoother finish and is often available in a wider variety of colors and finishes.
* Finishes: A flat finish is good for large surfaces such as walls, ceilings and floors because it doesn’t cause glare. On a matte surface, light is scattered instead of bouncing straight back into your eyes. This helps minimize the sight of imperfections in the wood, sheetrock or plaster surface.
Semigloss is good for high-traffic areas (kitchens, bathrooms, doors), trim and other woodwork because it’s easy to clean. Satin finish brightens up hallways and kids’ bedrooms by enhancing the reflection of light (called specular reflection), resulting in lively highlights that allow the color to shine through.
Gloss finish reflects the most light because its surface is like a mirror that bounces light straight back. It tends to be used in small quantities such as on trim and places that really need to be spotlighted.
* Primers are applied before the paint, preparing the surface so that the topcoat can go on smoother and more evenly. Primers also seal a porous surface, paving the way for good paint adhesion. Some primers can hide stains such as smoke damage or water spots. Deep colors such as red, yellow, orange and purple – “the ones your painter always tries to talk you out of using,” says Minchew – are hard to make look uniform and need a foundation laid before the paint is applied.
* Odor: Solvents are added to some coatings to soften the binder’s particles and to help form the film. Paints that are low in volatile organic compounds (VOCs) have few or no solvents, reducing the odor and irritants to nose and throat that are released when the paint is applied and drying. “You don’t want to feel as if you’re living in a chemistry lab,” says Minchew.
* Mix your paint if it’s been more than 24 hours since it was shaken up at the paint store. (The name of the machine that does this job: a dispenser.)
If necessary, thin the paint with a little water, otherwise use as is. “Paints have been painstakingly formulated to work just as they are,” says Minchew, who spent three years working on the Aura line.
* Climate: Ideally, don’t paint when it’s below 50 degrees, above 80 degrees or above 60% humidity. Hot weather will cause the paint to dry too quickly; low temperatures will make it cure improperly, which could hurt durability.
Paint is forgiving, says Minchew, but if the climate is too hot, too cold or too humid, save yourself and your paint for another time, or turn on a dehumidifier, heater or air conditioner.