Too thick of a coat: Applying too thick of a coat can extend drying times, leading to issues with subsequent layers.
Water-based polyurethane requires at least two hours of dry time between coats, and you should only apply two coats in a day.
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.
You are correct that, with polyurethane (brushed or wiped), you can recoat without sanding -- as long as you recoat within about 24 hours. After the poly has cured (usually about 3-7 days, depending on the product), you then have to sand. This abrades the surface and allows a mechanical adhesion between the two coats.
Triple Thick Polyurethane will be dry to touch in approximately 2 hours and can be recoated in 2 hours. Allow 48 hours cure before light use of the project. Allow 7 days for full cure.
Blotchiness and unevenness are caused by applying polyurethane too thickly, failing to stir it properly, extreme temperatures during application or drying, and applying additional coats too quickly. Following the manufacturer's guidelines helps avoid an uneven finish.
Allow each coat to dry fully. To give the subsequent poly layers something to bond to, sand lightly between coats with 320-grit sandpaper wrapped around a hard block. Note: The first coat needs the most sanding to appear smooth; don't worry if it doesn't look as flawless as you'd like at first.
Polyurethane will dry to touch in 3 hours. Under ideal drying conditions, allow 6 hours before recoating. Overnight drying is recommended.
Plain poly over the poly+stain will be totally fine. I would however be very careful when sanding now, as any sanding you do of the poly+stain will remove the color coat as well, and may lighten any areas that you sand more, especially on any high spots in the grain.
One evenly spread coat will make your furniture water resistant. Most furniture builders, however, will put on three coats, with a very light sanding using 0000 grit steel wool, then using a tack cloth to remove any dust before applying next coat.
While the polyurethane molding is much more durable than wood– it does exhibit the qualities of wood, and one of them is possibly getting dented on impact (i.e., the impact of a vacuum cleaner on a baseboard). The polymer baseboards can withstand those blows.
Three coats are usually enough for maple, cherry, walnut, mahogany, and birch. Poplar takes 4 to 5 coats. Pine and fir can require even more. I do not use wipe on polyurethane for open grain hardwoods like oak.
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.
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.
For maximum durability, we recommend 3 coats. Avoid heavy traffic and replacing of furniture for 72 hours after the final coat.
When it comes to hardwood floor polyurethane, lower humidity equals faster polyurethane dry time. So, one of the best solutions can be to use dehumidifiers to speed things along. Also, be sure to clean your air conditioner's filter before starting your project.
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.
While painting over polyurethane is doable, it is a process that requires some time and effort. However, when done well, it can rejuvenate old-looking cabinets, furniture, and other surfaces.
Make sure to sand the polyurethane between coats. Sanding removes drips, bubbles and other uneven spots in each coat. Dry the first coat for a full 24 hours. If the coat feels tacky or sticky after that, let dry until it feels completely dry.
Even though polyurethane is waterproof and weatherproof, if it's left in an area with high humidity levels or temperatures of more than 122° Fahrenheit (50° Celsius), the material will degrade. It should be kept away from these conditions to ensure that it lasts for as long as possible.
Make sure you are NOT shaking the can before opening. Stir thoroughly but gently and let it settle a bit before applying. Shaking will aerate the poly, filling it with tiny air bubbles.
If you're short on time, here's a quick overview: Composition: Polycrylic is water-based, while polyurethane can be oil-based or water-based. Application: Polycrylic applies in thin coats and dries quickly; polyurethane takes longer to dry.