Common Types of Hardwood Floor Finishes
When installing or refinishing wood floors, builders, installers, and DIYers need to consider the finish already on the floor and the one they plan to apply. Most site-applied floor finishes today are urethanes, either oil-modified or water-based, but moisture-cured urethanes, conversion varnishes, penetrating oils, and waxes are also used. Getting a healthy, durable finish also means understanding how moisture affects both the floor and the finish.
Wood Finishes
Wood floors installed before the mid-1960s were likely finished with varnish or shellac. It’s fairly simple to check: find an inconspicuous spot on the floor and scratch the surface with a coin.
If the finish flakes, it’s probably shellac or varnish, both finishes from an earlier era. Natural varnish made with vegetable oils gave way to vinyl-alkyd varnish, which in turn gave way to urethane.
Types of Wood Floor Finishes
Oil-Modified Urethane
One of the most common surface finishes, and easy to apply. It’s a solvent-based finish made from petroleum solvents blended with synthetic resins, plasticizers, and other film-forming ingredients, and it produces a durable, moisture-resistant surface. It dries more slowly than water-based finishes, typically in about eight hours. It has an amber color that deepens with age and comes in several sheen levels.
Moisture-Cured Urethane
A solvent-based finish that’s extremely durable and more moisture-resistant than other surface finishes, according to the National Wood Flooring Association. Moisture-cured urethane ranges from clear to amber and is generally available in satin or gloss. It’s difficult to apply, has a strong odor, and is best left to professionals.
This finish cures by absorbing small amounts of moisture vapor from the air, which makes it harden, so its curing depends heavily on relative humidity.
Water-Based Urethane
A waterborne urethane blended with synthetic resins, plasticizers, and other film-forming ingredients that produce a durable, moisture-resistant surface. These finishes are normally clear and non-yellowing and come in several sheen levels. They have a milder odor than oil-modified finishes and dry quickly, often in about two to three hours. Water-based urethanes are generally more expensive.
Conversion-Varnish Sealers (Swedish Finishes)
Two-component, acid-curing, alcohol-based finishes. Because they originated in Sweden, conversion varnishes are often called Swedish finishes. They’re clear to slightly amber and extremely durable.
Penetrating Sealers
Solvent-based sealers that are spread on the floor and allowed to soak in. The excess is wiped off with rags or buffed in with synthetic or steel wool pads. Many are tinted, so they can stain and seal the floor in one step. Penetrating oil sealers are made from tung or linseed oil, with additives to improve drying and hardness.
Paste Wax
One of the oldest floor finishes. Wax is inexpensive and easy to repair. It’s spread in thin coats after the stain or sealer is applied, then buffed to the desired sheen. Because wax over a penetrating stain sits in the wood rather than forming a film on top, you wear the wood instead of a surface coating. According to the National Wood Flooring Association, a wax finish is durable but needs more frequent maintenance than other finishes.
Varnish
Vinyl-alkyd varnishes replaced natural varnish made from vegetable oils and were commonly used before urethane finishes were introduced.
Lacquer
Lacquer is highly flammable, and many flooring manufacturers don’t recommend it for floors. It’s best avoided.
Shellac
Natural shellac contains wax and isn’t widely used as a topcoat on floors today. Dewaxed shellac is sometimes used as a sealer.
What Flooring Installers Should Remember
Every wood floor finish except wax involves moisture, because it’s applied as a liquid. And all wood contains some moisture, measured as its moisture content (MC).
Installers need to remember that the wood’s moisture, the stain, and the finish all interact with each other.
The relative humidity (RH) and temperature of the room also affect how well wood flooring holds up. When RH is low, wood loses moisture to the air; when RH is high, it gains moisture from the air. Before installation, installers acclimate the flooring as needed so its MC is close to its equilibrium moisture content (EMC) under the conditions the floor will see in service.
EMC is the MC at which wood neither gains nor loses moisture at a given temperature and RH. Wood flooring, and the finish on it, is more likely to fail when installers don’t make sure the flooring’s MC is right before installation and finishing.
Free Download – Wood Flooring Installation: What To Expect
How to Succeed
Measuring the MC of your wood flooring throughout the job improves your chances of a successful installation and finish. Give new flooring time to acclimate, and use an accurate wood moisture meter to prevent moisture problems.
Drying time is key. Keep the room within the finish manufacturer’s recommended temperature and RH range while the finish is applied and dries. Outside that range, finishes may not dry or cure properly.
Also make sure the stain is completely dry before you apply the finish, since finishing over stain that hasn’t dried can cause the finish to fail.
Finally, low RH and good airflow help a finish dry, even though those conditions aren’t ideal for the floor over the long term. Once the finish has cured, bring the room back to normal living conditions so the floor’s MC stays in line with its environment.
As Sales Manager for Wagner Meters, Ron has more than 35 years of experience with instrumentation and measurement systems in different industries. In previous positions, he has served as Regional Sales Manager, Product and Projects Manager, and Sales Manager for manufacturers involved in measurement instrumentation.
Last updated on October 8th, 2026
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