Water-based finish is made up of tiny, cured droplets of a solvent based finish, usually polyurethane or acrylic, that are dispersed in water. When the water evaporates, the droplets coalesce to form a continuous film. Because they use significantly less solvent than conventional solvent-based finishes, water-based finishes are less air polluting and safer to use. They also clean up with water and are non-yellowing. Those are the primary reasons for going with a water-based finish. They also score highly in terms of toughness and scratch resistance but are less resistant to heat, solvent, acid, and alkali damage than polyurethane (they’re more on par with a finish like nitrocellulose lacquer for those properties.)
Pros
- Safer and less polluting than most other finishes.
- Quick drying.
- Colorless and non-yellowing over time.
- Clean up with soap and water (no nasty chemicals).
- Good scratch resistance.
- No fish eyes or blushing in hot weather.
Cons
- Less resistant to heat, solvents, and acids than polyurethane.
- First coat tends to raise the grain.
- Difficult to remove after curing.
- Can have washed out appearance on dark-colored woods.
- Pricier than solvent-based finishes.
Brand Names
The marketing terminology of water-based finishes can be a bit confusing. You’ll see them sold as “lacquers”, “varnishes”, “urethanes”, and “polyurethanes”, implying that these finishes are similar to solvent-based finishes of the same name. The reality is that water-based finishes have more in common with each other than with solvent-based finishes, regardless of the name. Both classes of finishes do contain many of the same ingredients, such as acrylic, and polyurethane, but the resin transport and curing mechanisms are quite different.
Cabot Interior Water-Based Polyurethane
DEFT Water-Based Clear Wood Finish
Dura Seal 1000 Water Based Finish
General Finishes High Performance Polyurethane
General Finishes Polyurethane & Acrylic Blend
Minwax Super Fast-Drying Polyurethane for Floors
Rockler WunderCote Finish
Sherwin-Williams HYDROGLOSS Waterbased Urethane
WoodTuff Urethane Varnish
Application
Water-based clear finishes are typically milky white in color as a liquid but turn clear as they dry and stay that way over time. This makes them ideal finishes for light-colored woods such as ash, birch, and maple. They can be brushed or sprayed on but just keep in mind that they are generally more difficult than varnish to brush and more difficult than shellac or lacquer to spray. The key is to keep the coats as thin as possible to prevent sags and bubbles. Move fast if brushing because the finish dries fast. Avoid dragging over edges and recesses and watch out for foaming. Allow the first coat to dry and then sand with 280-grit or finer sandpaper to level off the raised grain and other imperfections in the finish. Brush or vacuum off the dust and then apply the next coat. Apply as many additional coats as you desire, allowing 1-2 hours between each (follow directions on can). Two to four coats is generally adequate.
