Recoat within 2 hours. If unable to do so, wait a minimum of 72 hours, then lightly sand and recoat. Apply at least three coats on unfinished wood and two coats on surfaces already finished. After final coat, allow 24 hours before normal use .
Polyurethane varnish is considered to be “ dry ” when the surface is no longer tacky and doesn’t have a wet appearance. At this point, it is safe to walk gently on the floor. Rough treatment can result in wrinkles in the finish or other surface blemishes, because the varnish underneath the surface is not yet “ cured .”
Apply a THIN coat of Minwax® Fast – Drying Polyurethane using a high-quality natural or foam brush. Let dry 4-6 hours. Then lightly sand entire surface with fine sandpaper (220 grit) to ensure an even finish and proper adhesion. Remove all dust.
Failing to sand between coats of polyurethane does not have a significant impact on the finish. Even so, I still advise that you sand between the coats when applying polyurethane as this will help increase the adhesion between the layers to give you a more level finish.
We recommend a minimum of 2 days of socks-only traffic for floors finished with oil polyurethane . The house is not inhabitable for a minimum of 2 days after the job is completed, and better to stay out for at least 5 as the fumes/off-gassing is not advisable to breathe in, even if there are other rooms to sleep in.
One of the simplest ways to speed up the drying time of your polyurethane finish is by applying very thin layers. Alternatively, if you have applied your polyurethane finish and you notice that it is taking longer to dry , then you can apply heat to it by the use of a blow dryer.
It takes oil-based polyurethane 24 hours and water-based polyurethane 6 hours to dry enough to be able to walk on it in socks and proceed to the next step of the application process (sanding or applying the next coat). Don’t confuse dry time with curing time which can take up to 1 month depending on conditions.
In-between Coats Always allow polyurethane to dry 24 to 48 hours before sanding, to give the surface time to cure and harden.
Multiple coats is the same as anything else. Multiple coats makes the coating thicker, stronger and more lustrous. Cars have multiple coats of paint to protect the body; you paint your walls with multiple coats to ensure even coverage; you poly furniture with multiple coats to ensure durability. Don’t sand to much.
If you experience oil-based polyurethane not drying well, it’s not likely that it’s bad polyurethane . It’s more likely that the wood you’re finishing contains a natural oil or you have applied an oil to the wood and the oil hasn’t dried. It will speed the drying , just not very much.
Oil based polyurethane “dries” in two stages. First the solvents evaporate leaving the resin behind. This normally takes on the order of hours, but as others have mentioned it depends on the temperature, humidity, and thickness of the finish. When the solvent has evaporated the finish will still be sticky .
Polyurethane is so durable and water-resistant, it has largely replaced shellac and varnish as a wood finish. Originally, it had to be brushed on, but different formulations mean it can now be applied as a spray or by wiping it on with a rag .
Sand lightly with 240-grit sandpaper between coats , then let the last coat dry for at least 24 hours. This is standard practice with any wood finishing job, and is nothing out of the ordinary. That said, sanding bare wood beforehand to create a smooth foundation is key.
Generally, more than 3 coats of poly doesn’t do much good. It’s really not needed nor recommended. Each additional coat needs to be buffed so you are kind of buffing off half of the previous layer. It’s kind of like nail polish where it takes longer and longer to dry and cure for each coat .
For protection, two coats are the minimum, but floors and anything else that will see hard wear or occasional moisture should get at least three coats . Each coat also makes the finish a bit smoother.