Can polyurethane be applied over paint? Well, it’s good to understand that poly is ideal on stained wood for a durable finish, but you can also use it over paint. It protects the paint and makes it durable by acting as a solid and resilient barrier safeguarding from dirt, fungus, rain, mold, and other factors. Applying polyurethane over paint also protects it from fading due to sun exposure. However, as useful as polyurethane is, misapplying it may lead to bad results. Here we’ve tried to discuss how you can apply polyurethane to your paint efficiently.
Different Paints and Polyurethane: Chemistry
While it’s possible to apply polyurethane, remember it might react differently on different paints. For example, on acrylic paint, the product still works well, usually applied on aviation and automotive refinishing. Polyurethane has replaced nitrocellulose lacquers since it incorporates better properties to handle high solid loadings.
Polyurethane will also work well on other paints like latex and white paint. One can use the product as a top coat over the paints. Such use is diverse than the usual spray coats since they cure fast and last longer. However, you need to get the right combination of about 10 percent solvent to ensure the polyurethane will form a solid finish.
Other than vehicle finishing, polyurethane can also work as a topcoat for airplanes. The paints with acrylic grades can blend with polymers for better action.
Unlike alkyds and drying oils that cure after the solvent reacts with oxygen and evaporates, polyurethane is different. Its coatings cure after the solvent evaporates but after reaction with various chemical reactions within the mixture. The solvent can also evaporate once it reacts with humidity from the atmosphere.
Do I Need to Apply Polyurethane after Painting?
Polyurethane over it keeps a painted surface safe from environmental factors. The product will offer a smooth finish even though it will take longer to dry. Provided the surface is clean and adequately prepared, you can apply polyurethane.
Simple Steps to Apply Polyurethane over Paint
Step 1: Clean the painted surface
Dirt, grease, and any other filth can affect the polyurethane application results. Wipe them off before you begin with the process. One can use a clean rag or sponge to clean off the painted surface for a boosted polyurethane adhesion on the surface.
Step 2: Scuff away
Once the surface gets dry, pick sandpaper and scrub the surface. The step is crucial in flattening the sheen and removing any deep scratch from forming. Large scratches may still be visible on the paint. If not sandpaper, one can also use a palm sander. But make sure that the paint isn’t removed from the surface.
Step 3: Deciding on how to apply the poly
When it comes to application, you need to decide on either using oil-based or water-based polyurethane. However, the difference between the two products is that the oil-based one incorporates an amber tint while the water-based one is clear. Moreover, oil-based is smelly and takes longer to dry when compared to water-based ones. We suggest using a clear topcoat (of course, water-based), as it will make the paint fully visible. When applying the finish, avoid using a roller since they tend to leave bubbles. It is better to use either a spray or a brush.
Step 4: Apply the first coat
Once you apply the first coat, leave the finish to dry for hours stated on the container. Once the finish cures, etch the surface with sandpaper to remove the smaller dust particles. The sanding is also crucial since it squishes and flattens any bumbles that harden on the finish.
Step 5: Apply your second polyurethane coat
In most cases, you never need more than a single coat, as a painted surface only requires a topcoat. With that in mind, make sure the finish from the first coat is fully dry before you apply the second coat (if still necessary). Use a soft brush to apply the second coat, making long and straight strokes. Make sure no bumps or bubbles are left for better finishing results. Once done with the second coat, please leave it to dry completely. Just check the container descriptions to know the exact dry time depending on your finish.
Paint Dry Time before Applying Polyurethane
In most cases, you need to wait for like 24 to around 72 hours for the paint to dry before you apply polyurethane over it. According to experts, you will get better results if you leave the paint to dry for longer. One needs to give the paint ample time to avoid issues.
Oil or Water Poly – What Performs Better on Paint?
Well, both oil and water-based poly will perform well. Oil-based ones look better with their own amber tint. Oil polys have more depth when it comes to shine and color, giving a hardwood look. On the other hand, a water-based one contains no such look – instead, they keep the surface color as it’s painted. If you prefer to have the paint color visible, this is your only choice.
Clear or Colorful Varnish on Painted Wood
A colorful or clear varnish can give a much facelift to any wooden project. Varnish protects the surface, preserves it, and enhances the paint. With so many varnishes and coatings, one can get confused about the ideal one. However, professionals agree that water-based varnish is the ideal one when it comes to applying over paint.
What Happens if You Paint Over Polyurethane?
Let’s alter the scenario!!
Home improvement trends change with each passing day, and painting is common among the many. But what if the surface you wish to paint has a polyurethane coat? Many wonders if it’s possible to paint over polyurethane without having to sand the surface. Even though sanding is a tiring process of such a project, it’s the crucial one. For effective results, you need to sand polyurethane first before applying the paint. Fortunately, you can apply paint over polyurethane if you sand the wood or any other surface. Doing that without following the sanding step, the paint will eventually peel off your project.
What Paint Will Stick To Polyurethane?
Unless the paint has primer, it will barely stick to polyurethane treated surfaces. Water-based acrylic and latex primers are not ideal for conditioning polyurethane. For that reason, you should use quality oil-based primers compatible with water-based paints. For the paint to stick to polyurethane, you need to sand it first.
Concluding Remarks
Polyurethane application over paint is an excellent way to boost the appearance of your furniture. The finishes protect the surface from scratches and make it resilient to water and heat. The surface is also easier to clean on top of adding sheen or gloss to your furniture.
