Will paint stick to polyurethane? Can I paint over polyurethane? And what do you use to prep for painting over polyurethane or poly?
Paint sticks to just about anything. It’s not magic, but a chemical reaction that scientists call adhesion. There are different types of paint, and some will stick better to more surfaces than others.
This article is about whether or not polyurethane paint will stick to polyurethane surfaces.
In this post, you will learn;
- Will Paint Stick to Polyurethane?
- What is Polyurethane?
- Why You May Need to Paint Your Polyurethane Funiture
- Why You Must Prepare the Wood Surface Before Painting Over Polyurethane
- Abrasives to Prepare Polyurethane Funiture Before Applying Paint
- Steps to Prepare the Polyurethane Wood Surface & Apply Paint
Will Paint Stick to Polyurethane?
Paint does stick to polyurethane. Painters use oil-based paint, water-based latex paint, or acrylic paint, on polyurethane because it binds well. The reason you don’t see a lot of painted polyurethane is that it is so durable and shiny that many people prefer to leave it alone.
What is Polyurethane?
Polyurethane is a liquid plastic polymer that, when applied to wood, creates a hard, durable coating. It can be sprayed or brushed on, and it only takes about two hours for the first coat to dry.
Some polyurethane finishes are oil-based while some are water-based. Polyurethane is available in various sheens, ranging from ultra matte to high gloss.
If you have polyurethane furniture that needs a new coat of paint, you can apply it just like regular wood furniture as long as you prepare the surface first.
But if you started with polyurethane, make sure it dries well before adding any coat of paint. You can learn
how long does polyurethane take to dry before painting to avoid any blunders.
Why You May Need to Paint Your Polyurethane Funiture
While polyurethane is an excellent surface coating, it’s not very flexible. It will tend to chip, peel or crack if the wood surface expands or contracts with temperature and humidity changes.
The best way to maintain your polyurethane-coated wooden surface is to repaint it with water-based latex paint or acrylic paint when it becomes faded or dingy. However, you must prepare the surface properly before applying paint over polyurethane.
Why You Must Prepare the Wood Surface Before Painting Over Polyurethane
Paint doesn’t stick well to glossy surfaces, and polyurethane is nothing if not glossy. Preparing the wood eliminates the gloss and creates a porous surface that accepts paint.
Remember, polyurethane creates a coating on your furniture that is designed to be permanent. If you don’t prepare this surface properly, the paint will chip and peel off easily.
Abrasives to Prepare Polyurethane Funiture Before Applying Paint
Sanding the finish off your furniture may seem like a lot of work, but sanding is the most foolproof way to make the paint stick to polyurethane.
An alternative to sanding is chemical preparation, which softens the polyurethane so the paint will adhere.
You have a choice of abrasives:
Using progressively finer grades of sandpaper is labor-intensive and time-consuming, but it works well. Start with coarse 60-grit sandpaper and work up to 100-grit for the smoothest surface.
If you choose this method, you must use oil-based paint after stripping. Water-based paints won’t stick over the residues left by water-based strippers. Strip only down to bare wood or use a bonding primer designed for slick surfaces over the final coat of stripper.
This is a clear finish containing fine grit that sands easily and provides just enough grip for the paint to adhere without having to strip the surface down to bare wood.
In a nutshell:
Sanding is effective at removing the surface and works on all types of polyurethane finishes, but it creates a lot of dust and may dull details on ornate pieces. Chemical preparation requires chemicals that have strong odors and must be handled carefully, but chemical preparation works quickly and doesn’t create dust.
Steps to Prepare the Polyurethane Wood Surface & Apply Paint
Step 1: Sand the wood
Sand the wood lightly with smooth sandpaper. Begin with a circular motion, then sand diagonally from one corner to another. Sand along the grain of the wood as evenly as possible. Do not apply too much pressure or you may leave depressions on the surface of the wood.
Step 2: Wipe away all dust
Wipe away all dust and debris left by sanding with tack cloths or a clean rag moistened with mineral spirits. Allow the surface to dry completely before proceeding to paint.
Step 3: Test compatibility
Test the compatibility of your paint and polyurethane by applying paint to a polyurethane piece of scrap wood. Wait until the paint cures completely to check whether they are compatible.
Step 4: Apply a bonding primer
Apply a bonding primer made for bare wood or previously finished surfaces. Follow your manufacturer’s instructions as far as how long to let it dry before applying paint.
You may be able to apply paint over the top of it once it’s dry to the touch, or there may be a specific window of time in which you can apply the top coat over the primer.
Paint the primer on in long, smooth strokes. Wait for it to dry completely before moving on to the next step. There is no need to sand the primer after it has dried, but you should make sure to check for any drips or other irregularities in the surface.
Step 5: Apply Paint
Paint on a coat of latex or oil-based paint. Either type will work fine, as long as you use the correct primer. Again, wait until it is completely dry before adding another coat, and then check for drips or other irregularities before going on.
If the piece looks blotchy after one coat, add another one. Let it dry completely, and then inspect it again before proceeding.
Step 6: Add a protective coating
Apply a clear protective coating if desired. This will help protect your painted finish from scuffs and scratches, but be aware that some types of clear coating can yellow over time when exposed to sunlight.
Generally, you should be able to paint over polyurethane as long as you use the right primer, paint and proper wood preparation methods.
Lastly, remember to test your paint on scrap pieces —if you apply paint over polyurethane and let things dry for a day or so, you’ll be able to tell more easily whether or not the paint will stick.