If you’re adding wood floors to your house or refurbishing existing ones, the most important step for protecting the wood’s natural color and warm grain from the onslaught of boots, pets, and kids is to finish it with a stain and a sealant. Unfortunately, many floor finishes contain harmful petroleum- and chemical-based solvents that emit volatile organic compounds, or VOCs, which compromise your home’s indoor air quality (sometimes even after they’ve dried) and damage your health when inhaled.
For health-conscious individuals, there’s a natural alternative: water-based wood floor sealants made with plant and animal ingredients that emit far fewer VOCs during application, which means fewer VOCs will linger in the air when the finish is dry.
Before chemically enhanced modern finishes, wood sealants were made from waxes, resins, and oils found in seeds and tree saps. Alcohol or turpentine—another natural product made by steaming pine heartwood—were the solvents used to turn the resins and saps into liquids. Shellac, perhaps the world’s oldest continuously used wood protector (first recorded being used to seal wood in the sixteenth century), is made by mixing denatured alcohol with a resin secreted by the tiny Laccifer lacca insect, found on trees indigenous to India and southern Asia. Painting on a coat of varnish made from tree sap, linseed oil, and turpentine was another common way to finish wood floors in decades past.
The wood-finishing industry changed with the rise in oil production brought about by the automobile and the 1937 invention of polyurethane, a clear coating made from petroleum byproducts. Petroleum-based solvents such as ethylene glycol or benzene (a petrochemical that the EPA has labeled a known human carcinogen) took the place of alcohol and turpentine. These solvents were combined with synthetic resins such as polyurethane.
As these new chem-based products flooded the market, woodworkers found that they actually worked better than their natural counterparts for finishing raw wood. Whereas polyurethane finishes can last years and are fully alcohol- and waterproof, waxes must be applied once a week and tung oils have to be reapplied at least once a year. Shellac is flammable, not waterproof, and actually dissolves when it comes into contact with alcohol. (A spilled gin martini can require that you refinish an entire floor if you’ve used shellac.) However, the danger in looking only at the convenience of modern floor finishes is that you ignore the inherent health risks in petroleum-based products.
As interest in healthy indoor air quality has grown, so have the choices for less toxic wood floor finishes. Many of these use water rather than a petroleum product as a solvent, which is why they’re referred to as water based. Old-fashioned ingredients such as tung oil, linseed oil, and carnauba wax have made a comeback, while new ingredients such as soy resin, orange peel oil, and beeswax have been added to the mix. Essentially, natural finishes use as much natural content as possible—up to 98 percent in some cases. For homeowners who are refinishing their floors, that’s a healthy figure.
Stains versus sealants
When you seal wood flooring, you’re protecting the wood by coating it with a thin sheet of glass-like material that resists scratching. Application of a water-based polyurethane sealant usually darkens wood permanently, as if it’s been covered with clear water. It brings out the wood’s true color, and that’s what most homeowners want. If you want to change the color of your floors to match your kitchen cabinets or living room furniture, use a wood stain. Unlike paints and sealants that just cover over a material, stains penetrate the wood grain so there’s no flaking or chalking—although stains that aren’t sealed will fade. Staining a wood floor is not the same as sealing it, so you must put a finish on top. “A stain can act as a base sealer, but you’ll always need a top coat to really protect the floor and keep the dirt from grinding in,” says Gerry Mueller, chairperson for the promotions and public relations committee of the National Wood Flooring Association and director of marketing for BonaKemi USA, a manufacturer of environmentally friendly floor finishes.
Like low-VOC finishes and paints, stains are also being made with indoor air quality in mind. Most companies that sell healthy finishes and paints also have a line of stains.
There has long been a concern that low-VOC, water-based products don’t perform as well as those made with petroleum bases and chemical solvents. When they were first created, water-based finishes were criticized for being less durable and more difficult to apply. The rumors spread, water-based products weren’t widely used, and people kept buying oil-based finishes. “They threw the baby out with the bathwater,” says Mueller. “The first generation of water-based products didn’t perform like they should have, and certainly not the way they perform now.”
According to Mueller, water-based floor finishes are now better than oil-based ones because they’re better for the environment and the health of those who apply them. In addition, they’re generally less problematic than solvent-based finishes for chemically sensitive people. Plus, with a new generation of more compatible chemical binders and additives, water-based finishes are now more durable than their oil-based predecessors. They’re also easy to apply, fast to dry, and their VOC content is far lower. “With a water-based finish you don’t even have to leave the house when your floors are being refinished,” says Mueller.