For centuries, finishes were made from natural resins collected from tree sap and insects, mixed with natural oils. Eventually, petroleum derivatives called “distillates” were introduced to thin the finish and increase its durability, and synthetic resins replaced natural ones. Today, most conventional finishes are either solvent- or water-based petroleum products. Some combine natural oils with petroleum distillates; others, such as polyurethane, are entirely synthetic. As a result, many conventional finishes contain volatile organic compounds (VOCs)—substances linked to poor indoor and outdoor air quality.
A VOC primer
Volatile organic compounds are found in many conventional building products, including carpet, insulation, plywood, paint and adhesives. They’re added to wood finishes to help sustain the product’s liquid form, enhance its performance and durability, and extend its shelf life.
As a finish is applied, it dries in place. During this drying period, the volatile solvents in the finish vaporize to a breathable gas. Finishes emit the most VOCs while drying, making them particularly hazardous for installers, but some continue to outgas for months or even years.
Associated with scores of environmental and health problems, VOCs contribute to air pollution by reacting with sunlight to form ground-level ozone, a major component of smog. Inside, their effect on air quality is even worse; the U.S. EPA has found that indoor air contains two to five times more VOCs than outside air.
VOCs range from safe to highly toxic. Unfortunately, most of the ones in wood finishes are toxic. Mineral spirits and petroleum distillates release vapors that can cause eye, skin, nose and throat irritation, and both are neurotoxins. Conventional wood finishes also may contain phthalates (plasticizers that improve spreadability), aromatic solvents (petroleum derivatives that aid drying), heavy metals and fungicides (to limit mold and mildew growth). Manufacturing these ingredients creates hazardous waste, and if leftovers are thrown in the trash or poured down the drain, they pollute the air and water.
The good news
“When people think of VOCs and air quality, they tend to think of paint—not the products for finishing their floors and wood trim,” says Dave Schaub, owner of Refuge Sustainable Building Center in Bozeman, Montana. “Fortunately, with the number of existing alternatives, there’s no reason you can’t finish or seal interior woodwork with healthier, greener products.”
According to EPA standards, stains labeled “low VOC” must not contain VOCs in excess of 200 grams per liter; the limit for varnishes is 350 grams per liter. You can, however, easily find low-VOC products that contain less than 50 grams per liter. “No-VOC” or “zero-VOC” finishes are very low in toxicity (five grams of VOCs per liter or less), but the name is misleading because it implies a completely VOC-free product.
Low- and no-VOC finishes generally fall under two categories: natural finishes (made with plant oils, tree resins, minerals and beeswax) and finishes that contain some petrochemicals but are water based and formulated to reduce air-polluting emissions. Some low-VOC and water-based finishes contain solvents, biocides and other harmful chemicals. People with chemical sensitivities always should test these products before using them.
If you look for healthier finishes in conventional hardware or home stores, you’ll likely come up empty-handed—most only can be mail ordered or purchased at home centers that specialize in sustainable products. Budget time to research and order the products or ask your local hardware store to special order your finish—and educate salespeople in the process.
Look for finishes certified by Green Seal, an independent nonprofit organization that sets standards for environmentally responsible products. Green Seal certification is based on VOC content, the absence of chemicals, durability, performance and manufacturing practices.
No matter what finish you choose, proper application and ventilation are key. “Read the directions,” Schaub says. “If you have questions, talk to the distributor or manufacturer. As always, a little research pays off in the long run.”
Wood finishing tips
• When choosing wood finishes for a chemically sensitive person, no product can be considered safe until that person has tested it. Even nontoxic, zero-VOC finishes release trace amounts of chemicals that some people may find irritating.
• “Organic” ingredients in wood finishes and other chemical products sound healthy, but they aren’t. Whereas organic foods are grown without synthetic pesticides (a good thing), in chemistry “organic” refers to chemicals that are carbon based, including volatile organic compounds, according to Green Remodeling (New Society, 2004) by David Johnston and Kim Master.
• Before applying any wood finish, read and follow safe-use directions on labels. To prevent skin irritation, wear rubber gloves during use. If you’re sensitive to fumes, wear a respirator mask designed to filter them.
• Even if you’re using a low-VOC product, open all doors and windows and use fans to move the fumes outside as quickly as possible. Do not inhabit the room until the finish has dried and fumes have dissipated.
• Many finishes are combustible, producing heat when they cure. This means oily rags might catch fire spontaneously; soak them in water after use. While they’re wet, seal them in a plastic bag and discard in an outdoor trashcan.
• Your friends, neighbors or local businesses or nonprofit organizations may be able to use leftover finishes. If not, call your sanitation department to learn about proper disposal methods.