Despite polyurethane's reputation for being able to increase the shimmer and sturdiness of hardwood flooring, this synthetic sealant comes with several disadvantages. Polyurethane floor finish is available in two main forms: oil-based and water-based, both of which you apply in several layers. These layers harden to form a protective, plastic-like coating on the floor. If you are thinking of using a polyurethane floor finish, take into account the problems you might encounter.
Applying Oil-Based Polyurethane
Applying oil-based polyurethane finishes is a pretty straightforward process: you just spread one coat of the finish, let it dry, spread on another, let it dry, and in some instances, you spread on a third coat and let it dry. The downside, however, as the home-improvement resource website The Family Handy Man notes, is that it takes about five hours for most oil-based polyurethane finishes to dry in between coats. Also, after the last coat, you need to wait an additional 12 hours before you can begin walking on it and using it regularly. To add discomfort to inconvenience, the oil-based polyurethane has a strong, unpleasant, chemical smell.
Applying Water-Based Polyurethane
In comparison to oil-based polyurethane, water-based polyurethane finishes may at first seem easier to apply. As The Family Handy Man notes, they dry within two hours of application. Also, they are water-soluble, so you can clean the polyurethane off your hands using just water, and they have a negligible odor.
However, while water-based polyurethane is faster-drying, it requires more coats, at least four, which will increase your work time. In addition, the solution is so transparent that you can have a hard time determining whether or not you have covered a particular area. This can cause you to miss spots or create lumps in the floor from over-application.
As the painting information website Paint Source notes, both oil-based and water-based polyurethane finishes form shell-like structures that cover wood flooring. These shells, while protecting the wood, also distort its natural textures and grain patterns, which constitute a large part of its natural appeal. In addition, oil-based finishes tend to leave an amber discoloration in floors, which some people dislike. Water-based finishes, on the other hand, can make floors appear cold.
While layers of polyurethane can protect underlying surfaces, they cannot protect themselves. As Paint Source notes, polyurethane floor finishes are prone to visible scratches and other blemishes, which could require that you add more layers. Water-based finishes are particularly soft and, as The Natural Handy Man mentions, require re-application approximately every two years.