If you want to display the wood on its own, then you’ll need some form of clear finish. Various oils and varnishes have been used to protect the wood for centuries. The most common clear finish is polyurethane, a tough polymer coating that’s durable, long-lasting, and easy to apply.
Depending on the formula, it can be used for interior or exterior applications and is available in oil-based, water-based, or water-borne oil formulas.
What is Polycrylic?
A newer type of clear finish from Minwax called Polycrylic sounds like it might be a type of polyurethane, but it’s different enough that DIYers should know the advantages and disadvantages of each before choosing between the two.
Polycrylic has a water-based formula, so it’s more environmentally friendly—it cleans up easily with soap and water and its VOC (volatile organic compound) levels are much lower, so it doesn’t emit the noxious fumes of solvent-based finishes. (Manufacturers still recommend adequate ventilation when using any finish.) The formula has an acrylic base; polyurethane is added for better adhesion and durability.
Polycrylic is not as durable as polyurethane and is meant to be used only on interior surfaces such as cabinets, furniture, and trim. It shouldn’t be used in exterior applications or on surfaces that are subject to lots of wear, such as floors, or that are exposed to water. There are other finishes, both solvent- and water-based, that are made specifically for floors and can handle the foot traffic.
How to Use Polycrylic
The recommendations for applying Polycrylic are similar to most types of finish, including polyurethane; it can be brushed or rolled. A high-quality synthetic bristle brush works well. It’s also available as an aerosol, which comes in handy if you’re finishing irregular or contoured surfaces.
Sheen choices include gloss, semigloss, satin, matte, and ultra-flat. Whether you’re brushing, rolling, or spraying, Minwax recommends a minimum of three coats.
A light sanding between coats will promote adhesion of the subsequent coats. At any time during the process, it’s recommended that you not use steel wool, because it can leave small particles that will rust in the finish. Instead, it’s best to use a nylon scrubby-type abrasive, such as 3M’s Scotch-Brite pads.
Polycrylic dries faster than polyurethane, so brush or lap marks can become a problem, making finishing large surfaces more difficult. It does take a bit longer to cure, however, so although it may be dry to the touch, it will take longer to dry completely. Polycrylic also has a thinner consistency than polyurethane, so you should watch out for drips and sags, especially if you’re applying it to a vertical surface.
Polycrylic vs. Polyurethane: Appearances Matter
Oil-based polyurethane imparts a slight amber tone to the wood, so it’s probably not what you want over a pure-white painted finish. Water-based polyurethanes lack that amber cast, but some still do cause white or light-colored surfaces to yellow after drying or become slightly cloudy over darker finishes such as milk paint.
Polycrylic, on the other hand, leaves a clear, non-yellowing surface, so it won’t change the appearance of lighter woods such as maple or birch, or anything painted white. Polycrylic is not recommended for use over dark-colored paints or red mahogany stain, however, where it’s clear appearance can become somewhat opaque or milky.
The next time you’re in the paint aisle in search of the perfect protective finish, consider these points:
- If your project is outside or might get tons of abuse indoors (like flooring), choose polyurethane. It’s tough. long-lasting, and relatively easy to use. However, in its oil-based form, it does off-gas during the drying process, so you’ll need adequate ventilation. And polyurethane imparts an amber cast to any surface, whether it’s raw wood or paint.
- On the other hand, if you have a project inside such as light-colored furniture or interior trim, polycrylic should be your pick. It doesn’t smell as much as polyurethane, and best of all, it cleans up with soap and water.