Yes, you can put polyurethane over paint. Specifically, polyurethane can be applied to latex paint, acrylic paint, chalk paint, enamel paint, and spray paint. You can use both oil-based and water-based polyurethanes on most paints. Multiple coats of polyurethane are needed to form an effective barrier on paint.
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.
Paint will not adhere to polyurethane treated surfaces unless they are primed. Water-based latex and acrylic latex primers are not appropriate for conditioning polyurethane. Applicators should use a quality oil-based primer that is compatible with water-based paints.
Yes. In fact, this option works so much better than the opposite: painting with a water-based paint over an oil-based layer. This is quite common when you use primers to prepare a wall, cabinet doors, or trim for the final paint layer.
“Polyurethane can be mixed with latex paint for a tough, durable finish that won't go gummy and sticky in humid summer weather like plain latex paint does. The finish will be the same color as the latex paint.”
Cons of Water-Based Polyurethane
Expensive cost. Requires more coats. Scratches easier due to it hardness.
Can you paint over polyurethane with latex or oil paint? You can, but you'll need to use a good primer first. Polyurethane creates a slick, plastic-like finish that most paints won't adhere to. A bonding primer will stick to the polyurethane and create a surface that's just textured enough to paint over easily.
Just roughing up the surface with fine grit sandpaper is enough to get the paint to stick to polyurethane. With a little elbow grease, you'll be ready to paint in no time! Sanding is especially important if you plan to stain the wood a different color instead of painting it.
Disadvantages of Water-based Paints
Water-based paints take longer to dry in high humidity and lower temperatures. Solvent-based gloss finishes have a higher sheen, but water-based keeps its sheen better throughout its lifetime. The finish is tougher and easier to clean but can become brittle with age.
Surfaces with varnish, polyurethanes, or other sealants or finishes require sanding before any paint can be properly applied. If not, the newly-painted surface will bubble, peel, crack or generally not stick.
A thin coat of bonding primer is going to be an essential ingredient to painting over polyurethane. Applying a good quality primer can help to prevent tannins from bleeding through your paint and ruining the overall color.
Polyurethane glue can be used to bond wood, metal, leather, tile, glass, rubber, brick and concrete. It isn't effective with plastics like polyethylene, polypropylene and chemically-created materials like Teflon.
Are water-based polyurethanes waterproof? Water based polyurethane is not waterproof. However, water-borne poly makes wood water resistant.
Water-based polyurethane gives the wood grain a softer, more muted look than an oil-based product, creating a more discreet and subtle appearance. It is best applied with a synthetic-bristle brush, though a foam brush is an option for smaller woodworking projects.
Spray On Polyurethane VS Brush On Polyurethane
If you're on a budget or new to DIY projects, brush-on polyurethane is a great place to start. Take your time and apply 3 thin, even coats for best results. For larger projects or if you want a flawless finish, spray polyurethane may be worth the investment.
Oil based used to be unquestionably more durable. Today though, water based polyurethane has evolved with better formulations that are equally durable as oil based polyurethane. High quality water based polyurethanes is considered by many homeowners & flooring professionals to be equally durable.
THICKNESS AND HARDNESS: Oil based poly is a thicker poly, but it is also softer. Water based poly, an acrylic product, is a thinner, but harder coating. Oil poly can be more susceptible to dents, while water based poly can be more susceptible to surface scratching.
The natural alternative is water based products. These replace the petroleum solvents with plant derived substances. These products are far safer for the health and well being of all concerned. You will have the peace of mind that no one is having their health at risk by exposure to VOC's.
DURABILITY: If each product is applied properly using quality products, the difference in durability is indiscernible. A lot of clients think that water-based poly is not as durable as an oil-based poly, but a quality water-based poly will last just as long if it is well taken care of!
Flooring wholesalers and veteran floor finishers agree that you can recoat water-based poly with oil-based as long as the original coating has completely cured—generally 30 to 60 days. You'll have to lightly buff the old finish with a power buffer to prepare it for the new polyurethane.
The surface can discolor or dry streaky if you don't sand between coats of polyurethane.
How long does it take for water-based polyurethane to dry on hardwood floors? Most of the time, it takes about 4 hours. You can walk on the floor gently after 4 hours without your shoes. It will take about 30 days for it to fully cure, though.
Klean-Strip QWN285 Easy Liquid Sander Deglosser
With an easy-to-use, less toxic formula that's designed to cut through grime, this liquid sander deglosser from Klean-Strip can remove paint, lacquer, polyurethane, enamel, and varnish.
With the fine-grit sandpaper, softly sand down the brush markings while applying even pressure to the area. To remove any traces of dirt and grit from the sanding, wipe it off with a soft cloth. These particles may become trapped beneath the finish.