It provides protection against a variety of scratches and other damage, keeping your floors in pristine condition and tempering the hardwood material for years to come. You should use at least 2-3 layers of polyurethane on your wood floor.
Aim for at least three coats, allowing each layer to dry thoroughly before applying the next. Lightly sand between coats with a fine-grit sandpaper to ensure better adhesion and a smoother finish. This technique not only enhances durability but also gives the floor a richer, more polished look.
If you do a second coat within 24 hours it'll have a chemical bond without the need for sanding. If more than a day passes between coats you need to lightly sand to give enough tooth for a physical bond.
Two coats of finish are suggested for most interior projects. When sealing floors, you should apply three coats. However, do not apply more than two coats in one day. 220 grit sandpaper should be used between coats to remove any air bubbles, but avoid using steel wool.
Polyurethane will dry to touch in 3 hours. Under ideal drying conditions, allow 6 hours before recoating. Overnight drying is recommended.
The average dry time for water-based finishes is 2 to 8 hours while other urethanes dry between 4 to 24 hours. It is safe to lightly walk on the floor the day after we put on the last coat of finish however, we recommend waiting at least 24 hours before placing any furniture.
Humidity and Temperature: Polyurethane dries faster in lower humidity and higher temperature. At increased temperatures, the polyurethane will dry faster, at lower temperatures it will take longer. A temperature of 70F and 50% humidity is what it takes for the average dry times mentioned above.
Contrary to popular belief, no further buffing is necessary after the finish dries. Polyurethane dries to a pre-determined level of shine (the can will tell you whether it's satin or semi-gloss). Its luster will be dulled by any further buffing or polishing.
Lambswool Applicators
The method recommended for applying oil-based polyurethane to hardwood floors is with the use of a lambswool applicator on a wooden block. One word of caution with lambswool applicators: The fibers of these applicators have a tendency to get stuck in wet finish.
Waterborne polyurethanes usually require a minimum of 3-4 coats to be effective. Although there is some evidence that too many coats can result in a plastic-like finish, waterborne polyesters are thinner than other types and therefore require several more coats to provide the same protection for hardwood floors.
Prepare the polyurethane by reducing it about 10 percent with mineral spirits, unless you're using water-based polyurethane, which doesn't need thinning. Thinning the polyurethane makes it flow on more smoothly and reduces brush marks. Quick Tip!
You should use an automotive polishing compound and a buffer for big areas. Small areas will have to be polished by hand unless you have some funky buffing tools. Make sure the poly has cured for a minimum of 4-5 days at 70f. Do not try to polish an uncured film.
Varnishing your floor
Three coats will give you the best protection and finish, so wait two hours for the first coat to dry. If you're not using Diamond Hard Floor Varnish, check the manufacturer's instructions to see what the dry time is.
One gallon of polyurethane covers 350 square feet.
A roller is the recommended method for applying some water-based polyurethanes, as well as some oil-based polyurethanes and moisture-cured poly finishes. Rollers are good for finishing multi-direction floors, like parquets.
Oil-based polyurethane often dries more slowly than its water-based cousin. It's best to wait at least 24 hours before wearing socks and walking on the floors. Full Cure: It's advised to wait at least 72 hours before moving furniture back in, even if you might be able to walk on the flooring after just one day.
Polyurethane is the water-resistant layer your contractor applies to protect the wood and give it a beautiful sheen. Water-based polyurethane finish is the best polyurethane for hardwood floors, and many consider it the future of polyurethanes.
Do I need to sand between coats of polyurethane? Yes, sanding between coats is important.
One way to increase the hardness of a flexible polyurethane foam at constant density is to increase the degree of crosslinking in the foam network. This can in turn be achieved by various measures. First, it is possible to increase the isocyanate index.
Surfaces finished with oil-based polyurethanes can be used after around 4 days, but full cure normally takes 30 days. Even if the manufacturer's recommended time has passed, if you can still smell the polyurethane, it probably isn't dry. Fast-drying polyurethane is available in both water- and oil-based formulas.
There are several ways to determine whether a surface is dry: OIL BASED products are dry if they are no longer tacky and do not emit a smell. WATER BASED products are dry if they no longer feel cool to the touch and a powder will form with light sanding.