Water-Based Finishes: What Should You Know About Them?

by: Megan Cherry

It's true that many believe water-based finishes are safer than other finishes, and that they are also safer to handle. However, water-based finishes still use some of the same resins used in urethane and acrylic finishes. Water-based finishes are indeed much safer than traditional lacquers, but you should still be careful when you use them. Most of you have used latex paint before. Therefore, you know that the fumes can be quite intense, especially in an enclosed space. This is also true for water-based finishes, and you'll want to take proper precautions to protect both your skin and lungs. Make sure there's adequate ventilation, wear proper protective clothing, and wear a respirator as well.

Many harmful additives have been replaced by water in these types of finishes. The resins are not easily mixed with water, though, so they have to be chemically modified in order to be emulsified with the water. These require chemicals called surfaces and solvents to be added; among these are glycol ethers, which force resins to mix with water.

Yet another problem with water-based finishes is that the water will often raise the grain in the wood. Try this sometime. Sand a piece of wood and then rub some plain water on it. You'll notice that the wood fibers will absorb the water and swell, which makes them "stand up" and roughen. To get around this problem, you can use a seal or coat of shellac. This will add a barrier between the wood and the next coat of finish. It will also give your wood a little bit of an amber color. Alternatively, you can use a couple of light coats of standing sealer. Once the standing sealer has dried, you can lightly sand the wood, which will smooth it out.

Fortunately, though, water finishes are of a neutral color, which means that they don't add any color to the wood as other finishes might. Other lacquers might cause a slight amber color to the wood. Therefore, if you want to keep your wood's natural color without any distortion whatsoever, a water-based finish is a great choice. However, there are certain woods that do not do best with a water-based finish. These are the darker woods such as cherry or walnut. If a water-based finish is applied, this tends to "tone down" the color of the wood so that the deep rich wood color is somewhat negated with a water-based finish.

Therefore, water-based finishes have both pros and cons. Pros are that they are not flammable and are less polluting than traditional finishes are, they don't yellow, dry fast and can be either sprayed on or applied with a brush. In addition, water-based finishes have much less of an odor and clean up is much easier than it is with other types of finishes. However, they have drawbacks too. Most cannot give wood a deep, rich color as we are used to with a solvent-based finish. In addition, the water raises the wood's grain and can be very difficult to apply, since humidity and temperature play a role in both application and drying times.

In addition, with water-based finishes, the tools you'll need will be slightly different than those with solvent-based finishes. For example, steel wool will rust quickly with water-based finishes, and natural bristle brushes will absorb too much water and become limp. In addition, if you're using either a conventional or high-volume low-pressure spray gun, you'll need to have stainless steel needles and nozzles so that corrosion does not happen.