Nuts + Bolts
With the Grain
November/December 2004
By Sam Martin
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Water-based wood floor sealants emit fewer VOCs during application, meaning fewer toxic emissions linger in the air.
Photos Courtesty of BonaKemi USA
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There’s more to environmentally friendly floor stains and finishes than meets the eye.
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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.