Wood floor finishes

Wood floor finishes have changed and improved over the years. Research and science has helped improved the product that we use today. Making the wood floor finish better, easier to use and safer for our health and environment. With all the changes, the basic ingredients are the same. It all contains a solvent, dryer, leveling and matting agent. Some products may include de-foamers, catalyst, hardener and viscosity modifiers. Read along, to learn the general knowledge and how to use these different types of wood floor finishes available on the market.

Wood floor finishes : Sealers - types of base coats

Oil-modified sealers: These are similar to finish topcoats, but with less solids and more solvents. The additional solvents helps the sealer to dry faster. It is combustible, meaning it can burn, has a moderate odor and dries between 2-6 hours. You must abrade this type of sealer prior to applying a topcoat to avoid adhesion issues. Generally, only one coat is allowed. Some of these sealers maybe illegal in your area, due to its VOC level. Check with the manufacturer for their application guidelines.
Water base sealers: Its primary functions is to prevent tannin pull, panelization, side-bonding along with assisting in film building for water base topcoat wood floor finishes. There are three types of water base sealers: acrylic, urethane and acrylic/urethane blend. It has a low odor, fast drying time, usually 1-4 hours and is non-combustible. It does not need to be abraded under 48 hours, unless to remove dust and debris. The best application method is using a T-bar with a snow plow method with finger-tip pressure. Urethane water base sealers can be applied in multiple coats for a higher film build.
Shellac: Is an alcohol base sealer, that has many benefits. Avoid using natural shellac, it contains wax and is not recommended under topcoats. It can cause adhesion issues. Instead use de-waxed shellac, which is a universal sealer. You can use de-waxed shellac over aniline dye and then apply a water base wood floor finish to prevent the aniline dye from moving around. Apply a thin coat and do not abrade the shellac, when top coating. The dry time is usually one hour, depending on the job site conditions. You can also, tint shellac and use it as a toner coat. Check with the manufacturer for application and abrading guidelines.
Stains: Some stains are considered sealers. The benefits of multiple products in one. It eliminates the step for applying a sealer coat. You can apply a top coat directly on top. These types can require an abrasion prior to top coating. Check with the manufacturer for their application guidelines.

Film Forming Top coats

Oil base polyurethane

Oil-Modified Urethanes: A yellow film forming wood floor finish with easy application, self-leveling and durability that can be applied on residential and commercial wood flooring. It has a moderate odor, ambering color and long dry times. It can be applied with a lambs wool, T-bar, brush, pad or roller. Intercoat abrasion is required in-between coats to prevent adhesion failure. Dry time is between 8-24 hours. Oil-modified urethanes will alter the final appearance of a stain finish. Colors should be sampled with finish. Cure time is between 14-30 days, depending on the manufacturer.
Water Based Urethanes: A clear film forming hardwood floor finish that is easy to apply, exceptionally durable and self-leveling that can be used on residential and commercial wood flooring. These are either acrylic or emulsified urethanes carried by water. It is available as a one or two component finish. One component water base polyurethane floor finishes have a long pot life. Which helps reduce waste. With two components, once mixed you have a limited pot life, increasing waste. These wood floor finish can be applied with a pad, T-bar or roller. It is non-flammable and has a fast drying time, keeping a wet edge is very important to help avoid lap marks and brush marks. Water base urethanes do not require abrasion under 48 hours, unless dust and debris needs to be removed. Depending on the manufacturer, the cure time can be between 3-14 days.
Moisture Cured Urethanes: A clear film forming wood finish with extreme durability and chemical resistant solvent based urethane. This finish cures with humidity. The higher the humidity, the faster. Making it a challenging finish to apply in high humidity conditions. Dry time can be as short as 30 minutes, with a full cure within 7 days. It has a very strong odor and is flammable. All open flames should be turned off prior to application. Intercoat abrasion is required for adhesion. Abrading can be challenging with its durability level. Two to three coats is required. Moisture cure urethane maybe illegal in your area with VOC's between 500-700. There are low 350 VOC moisture cure finish available.
Tung Oils: A clear film forming wood finish that seals and finishes. It can darken over time. Some are hybrids and synthetic blends. It is considered combustible and has a strong odor with a long curing time up to 90 days. Drying time can be between 6-48 hours depending on the job site conditions. Best application method is with a lambs wool and brush. Multiple coats are usually needed for sufficient coverage. Intercoat abrasion is not required for adhesion, unless dust and debris needs removal. Check with the manufacturer for application guidelines.
Conversion Varnish or Swedish/Acid Cure Finish: A two part solvent based clear film forming finish with excellent durability and chemical resistant. Similar to a moisture cure, but it does not dry with humidity. It requires a catalyst to harden and cure, where the catalyst contains acid. It also, requires air movement to assist in drying. Any trapped vapor will slow the drying process. The cure time can take up to 90 days. A heavy handle T-bar is best for applying conversion varnishes. Two to three coats is required. Do not over abrade these finishes, scratch marks can show through and it can affect the adhesion.
On-site UV Cured Finish: A clear water base wood floor finish with exceptional durability, self-leveling and is easy to apply with the benefits of an instant cure. When exposed to high intensity UV light, a cross linking reaction cures the finish instantly. It has a mild odor and the UV light can cause skin cancer if, unprotected. These finishes do not always need abrasion. Check with the manufacturer for application details and guidelines.
Natural/Hard Wax Oils: Penetrates to a certain depth and fills the fibers of the wood, protecting it from within. "Some" penetrating oils can be top coated with finishes. The benefits of these finishes are easy spot repairs, can be stained and finished in one step and endless unique coloring option. Several colors can be layered for a Ceruse effect. This type of wood floor finish requires frequent maintenance coats to ensure proper protection to the hardwood floors and does not resist chemicals well. Generally one or two coats is required. Check with the manufacture for application guidelines.