Yes. First you have to sand the polyurethane with 150 grit sandpaper to scuff the surface and knock the gloss off. This will give the surface “teeth” for the primer to bond to. Prime the sanded surface using a quality acrylic primer or shellac.
If everything was done correctly, your polyurethane surface should be ready for paint without any issues. Water-based paint works just fine if your surface is primed correctly, however it's recommended you use oil-based paint for a more superior, long lasting finish.
Since the paint won't bond over polyurethane, it would be better to remove the finish with paint remover or sand it down thoroughly, effectively etching the surface of the polyurethane until there's no sheen left. Then it would be best to use a primer first before final painting.
Yes, it's possible to paint over polyurethane, but it requires the right preparation. Polyurethane coatings are tough and glossy, which can prevent paint from adhering properly. To paint over polyurethane successfully, you'll need the right materials, careful prep work, and a bit of elbow grease.
The short answer is yes, to a certain degree. There are several factors that make some polyurethanes more absorbent than others. Depending on the physical properties and material, thermoset polyurethanes can practically have zero water absorption compared to other known materials.
Each coat should be ready to re-coat in about 2-3 hours with a water-based finish and typically overnight for oil-based. The beauty of water-based finishes is typically you can recoat without abrading.
Acetone is far from the only option available if you want to remove polyurethane. Many people use sanding strips, sanders, or metal scrapers to gradually remove the substance. You might also opt to use a planer, which trims the surface to expose the bare wood underneath. Chemical strippers are another popular option.
Enhanced Durability
Polyurethane acts as a protective coating, helping to minimize the appearance of scratches, dents, and general wear. This hard-wearing finish is particularly suitable for families or high-traffic kitchens, ensuring that your cabinet doors maintain their integrity and appearance over time.
Because it's an acid, vinegar can eat away at hard finishes like polyurethane and wax. Use only white vinegar, diluted with water, on soft floors that are finished with an oil-based coating.
Make sure to sand the polyurethane between coats.
All types of wood require at least two coats of oil-based polyurethane. The first coat works as a primer and sealer; the second serves as a finish coat. With water-based polyurethane, a third coat is recommended, because the finish wears away fairly quickly. Sand between coats if dust or lint gets into the wet finish.
Bonding primer: Specially formulated primers can create a strong bond between paint and varnish, even without sanding. However, these primers can be expensive and may not be as durable as a sanded and primed surface.
For bonding rigid PU, we recommend using polyurethane adhesives such as Araldite 2018 and Araldite 2028-1 and structural acrylics; Permabond TA4204.
MAGNOLIA HOME BY JOANNA GAINES® TRIM, DOOR + CABINETRY INTERIOR SEMI-GLOSS PAINT 4.5 out of 5 stars, average rating value.
Vinegar breaks up the grease without damaging, causing any abrasion to the polyurethane. Because vinegar works like a glass cleaner, it also won't cloud the finish like other cleaners and can break through any buildup.
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.
Removing polyurethane from wood without sanding can be challenging but possible using mechanical methods. One option is to use a heat gun or infrared paint remover to soften the polyurethane, then scrape it away with a putty knife or scraper.
If you don't mind a little variation in texture, 3 coats of poly should be more than adequate. Sand lightly after each coat as dried and dust thoroughly before applying the next coat.
How Many Coats of Water-Based Polyurethane are Necessary for a Project? Two coats of finish are suggested for most interior projects.