Many people don’t know that polyurethane-treated surfaces can be painted, mainly because it wouldn’t occur to finish with polyurethane then paint. When furniture or other wood products come pretreated with polyurethane, and you want to paint them, you don’t have much of a choice. In such a case, what kind of paint will stick to polyurethane?
Nearly any kind of paint will stick to polyurethane as long as the wood is sanded and primed properly. Oil paints provide durability at the cost of strong fumes, while acrylic is slightly more fragile but lacks strong smells. Products like Oil Bond can sand and prime at the same time.
In this article, I’ll discuss polyurethane, what paints work on it, and some other relevant information that may interest you.
What Is Polyurethane?
Polyurethane is essentially a type of liquid plastic used as a topcoat commonly applied to wooden floors and furniture.
When applied to wood or another material, it dries into a clear, shiny, and durable clear coat. This protects the surface from damage from scratches, scuffs, impacts, and other damages. The material is available in oil-based and water-based variants, with varying levels of luster.
Can You Paint Over Polyurethane?
You can paint over polyurethane, but there are some caveats to keep in mind when you want to do so.
Firstly, it becomes crucial to sand the area, even more so than when freshly painting it. Paint doesn’t stick to glossy and unsanded polyurethane very well at all and will likely peel off if applied without prior sanding.
Another consideration is primer. Paint may not stick to even well-sanded polyurethane surfaces, which is where primer comes in.
Primer is similar to paint but serves the purpose of preparing the surface for painting. Some products like Oil Bond from Amazon serve the dual purpose of ‘sanding’ and priming the surface.
What Type of Paint Will Stick to Polyurethane?
Nearly any paint will stick to polyurethane-treated surfaces, given the proper preparation. The surface should be either sanded or primed with a product that serves as a ‘liquid sander,’ as previously mentioned.
Priming after sanding is ideal for giving your paint the best chances of adhering to your surface and staying there for a long time.
Another lesser-known benefit of using a primer before painting is that stains in the wood won’t come through the paint. This can occur with some strongly-colored wood stains.
Oil-based enamel is typically used when you want your surface to remain durable without compromising the protective qualities of the polyurethane finish, but it produces unpleasant fumes.
Acrylic paints produce similar results in a much faster time frame, even if it’s a bit less durable. The other pro of acrylic paint over oil-based paint is that acrylic doesn’t smell as strongly.
If you’re not sure what type of paint to use, you can check out this article on different types of paint.
How To Paint Over Polyurethane
Painting over polyurethane finish doesn’t have to be complicated or stressful and will be pretty simple if you follow some simple preparation and steps.
1. Clean the Surface
Cleaning the polyurethane-treated surface you wish to paint is perhaps the most important step.
Using mineral spirits, wipe a damp cloth across the entire surface area of your wooden piece. This will help to remove dirt, dust, grime, and other undesirable muck from your wood.
Don’t rush this step, even if you’re impatient to get painting: rushed cleaning will be evident once you paint and the paint isn’t adhering well.
Use a separate dry cloth to wipe dry debris from the wooden surface, being extra careful to get the cracks and crevices around the edges.
2. Sand the Surface
Using fine sandpaper or a sander with fine-grade (200+ grit) sandpaper, carefully sand away the surface of the glossy polyurethane surface layer.
You don’t want to completely remove this layer because that will remove its protective benefits. Just sand until the gloss is gone and the wood looks ‘dull’ compared to before.
After sanding, clean with mineral spirits and another dry cloth. There will be a lot of dust and debris, so be sure to get all the nooks and crannies — edges, corners, and so on. If you’re using a liquid desanding product, feel free to disregard this step.
3. Prime and Paint the Surface
Using long and even strokes, apply the primer to the surface of your wood. Uneven brush strokes can undermine the longevity of your efforts, leading to shoddy paint. Once your initial layer of paint is dry, lightly sand uneven or splotchy areas and repaint, allowing it to fully dry.
Related post: Wood Stain Vs. Varnish Vs. Paint
While polyurethane is a finish for wood, it’s perfectly possible to paint over it. Acrylic and oil-based paints are perfect for painting over polyurethane-treated wood.
To do so, the most important step is to clean the surface with a damp cloth. Then use a fine-grade sandpaper to gloss the surface. Finally, apply the paint and primer with long even strokes.