By Bruce Johnson
For more than a century, traditional hardwood floor finishes have been oil-based. Recently, oil-based finishes have been strengthened by the inclusion of a polyurethane additive, which has resulted in most now being called “polyurethanes.” Oil-based finishes, while proven to be tough, do present three challenges.
First, as the mineral spirits in oil-based finishes evaporate, they create fumes that have to be diluted with fresh air, either by opening an exterior door or window, or setting up a fan to blow air through the room. The problem this creates, of course, is that it pulls dust particles into the room—and onto your wet, sticky finish. In addition, if the temperature outdoors is below 65 degrees, the influx of cold air could cause the temperature in the room to drop below the recommended level for proper drying.
Oil-based products also take longer to dry than their water-based counterparts. In addition to preventing us from using the room sooner, the slower drying time always means that the oil-based finishes will remain susceptible to dust and dirt for a longer period of time.
Finally, oil-based finishes require mineral spirits for cleanup, rather than soap and water. While this shouldn’t be a major consideration, it can’t be ignored.
For these reasons, research and development teams have spent much of the past 30 years working on a water-based formula that can replace the traditional oil-based floor finish. On the surface, it appears they have succeeded.
Water evaporates faster than the mineral spirits in oil-based finishes, which makes the drying time of a water-based product minutes rather than hours. In addition to speeding up the entire project, a faster drying time also means less opportunity for troublesome dust to get caught in the finish. Plus, as it evaporates, water does not create any dangerous fumes.
Water-based finishes can be cleaned up with soap and water. However, this does not mean that a cured water-based finish can be dissolved or softened by water. Once the resins have hardened, they are water-resistant.
But are water-based finishes as durable as oil-based finishes? They’re getting there. If, in terms of durability, the perfect floor finish is a 10, then most experts would rate the best oil-based polyurethane varnish a 9, followed by the best water-based polyurethane finish at an 8—and closing in fast.
When deciding whether to choose a water-based versus an oil-based finish, consider the time of year, the amount of time you have for the project, the effect the project will have on your family, the level of use the floor will receive, then ask yourself the following:
- Will I be able to provide the ventilation required by oil-based products?
- Is drying time a factor?
- When compared to these answers, how important is the difference in durability? In other words, can I sacrifice a small degree of durability to avoid fumes and to reduce the drying time?
Once you’ve settled on a finish, you’re well on your way to a beautifully recoated floor.Published in: Old-House Journal December/January 2011