Polyurethane is a synthetic resin that is often used as a protective coating for furniture, floors, and other surfaces. So it’s normal that we ask ourselves if we can apply a coat of paint over polyurethane?
You can paint over Polyurethane but you need to prepare the surface first by sanding and priming it so the paint can adhere properly. Painting without sanding and priming would lead to flaking, cracking, and peeling.
To give you a better understanding of the logic behind it, let’s first look at why polyurethane serves as a protective coating.
Why most wood surfaces are covered with polyurethane paint?
Many different types of coating can be used for wood surfaces. These include shellac, lacquer, varnish, and polyurethane. Polyurethane is one of the most common because it is extremely durable.
Polyurethane forms a very smooth layer that protects the substrate from moisture and mechanical damage. It also enhances the appearance and smoothness of the substrate to a certain degree.
Is it possible to Paint Over Polyurethane?
You can paint over polyurethane if you sand and prime it first because moisture can’t pass through it otherwise. Using Primer will help to bond your paint with the surface and conceal any flaws caused by sanding.
NOTE: Make sure the primer you're considering is suitable for the paint you'll be using. If you're applying oil-based paint, use a suitable primer; if you're utilizing water-based paint, choose one that's appropriate for it.
Which type of paint will stick to Polyurethane?
Paints usually fall into two categories: oil-based and water-based. You can cover Polyurethane with both but there is a slightly different approach, how you do it.
Oil-based paints are more durable and have a longer life, but they also take a longer time to dry. Water-based paints look more glossy and are easier to clean up, but they will probably not last as long.
How to pain on Polyurethane with Oil-based Paint?
Oil-based paint will adhere to polyurethane if the surface is sanded and an oil-based primer is applied beforehand. You can apply it over other old coatings such as lacquer, enamel, and varnish which is a great advantage.
Follow these easy steps when using this type of paint:
- Sand the surface thoroughly with medium-grit sandpaper to remove any imperfections or old coatings.
- Wipe the surface clean with a tack cloth and using degreaser like TSP
- Apply an oil-based primer.
- Wait for the primer to dry completely.
- Paint the surface with your desired color of oil-based paint.
- Apply multiple coats if needed.
- Let the paint dry and apply a protective clear coat if desired.
How to paint on Polyurethane with Water-based Paint?
Water-based paint can adhere well to polyurethane but you must take certain precautions or steps beforehand.
Latex or acrylic latex primers will not work well with Polyurethane. Instead, professionals use a high-quality oil-based primer that is compatible with water-based paint for long-lasting results.
Follow these easy steps when Applying Water-based Paint:
- Sand the surface thoroughly with medium-grit sandpaper
- Wipe the surface with a degreaser like TSP and allow it to dry completely.
- Apply a coat of primer that is compatible and follow all safety instructions.
- Apply a top coat of water-based paint following the same techniques as you would for any other surface.
Painting with different types of Water-based paints over Polyurethane
On the market, there are several different types of water-based paints available. each has its own unique benefits.
Painting with Acrylic paint
Acrylic paint is the most popular type of water-based paint. It comes in a wide range of colors, each loaded with pigments that produce rich, opaque colors. It can be great for painting over polyurethane because it cures quickly and will not lift any old paint layers that may be beneath it.
The drawback would be its price. If you need to cover a large area with this paint, you’ll be spending a lot of money.
NOTE: Make sure you follow the instructions/steps above for best results.
Painting with Latex paint
Latex paint is another popular type of water-based paint. It’s easy to use, dries quickly, and cleans up with soap and water. It also comes in a wide range of colors and finishes.
Latex paint is a good choice for painting over polyurethane because it adheres well to most surfaces and will not discolor with age. The downside is that it’s not as durable as other types of paint and may not last as long.
Painting with Enamel paint
Enamel paint is a type of paint that has been around for many years. It comes in a variety of finishes, including high gloss, semigloss, and eggshell. It’s easy to apply with a brush or roller, or you can spray it on for maximum coverage in no time.
In addition, you can use it for painting over polyurethane as well when following steps applying water-based paint above..
KEEP IN MIND: The enamel is not as durable as other types of paint and may not hold up as well over time. It's also a more expensive type of paint to buy.
Painting with Chalk paint
Chalk paint is a relatively new type of paint that has been gaining popularity in recent years. It’s water-based paint that dries to a matte finish, giving your project a unique look.
Since it’s water-based, chalk paint is easy to use and can be applied over polyurethane with no problem but I highly recommend sanding surface first. This is especially important if the surface is high gloss.
NOTE: Chalk paint is available in a wide range of colors, so you're sure to find one that will complement your project.
Do You need to seal the paint, when painting Polyurethane?
Yes, it is always a good idea to seal paint when painting Polyurethane. This will help to protect the paint from chipping or peeling over time. The type of sealant you will you, depends on the material you are painting over.
Wooden surfaces should be sealed with a polyurethane sealant, while metal surfaces should be sealed with a rust-resistant sealant.
What Type of Brush Should I Use to Paint Polyurethane?
When it comes to brushes, there are a few different types to choose from. For best overall results, use a brush with synthetic bristles. They are durable and inexpensive. In addition painting over Polyurethan normally doesn’t need to be that precise, where a brush with natural or nylon bristles would be needed.
NOTE: When purchasing Synthetic brushes, avoid buying the cheapest on the market since they may leave bristles on your furniture or object you are painting.
I love Pro Grade brushes for this purpose.
Do I Need to Strip Polyurethane Before Painting?
No, you do not need to strip Polyurethane before painting. However, it is always a good idea to sand any old paint layers that may be beneath the Polyurethane. If you don’t sand your surface, you could end up with paint peeling. Some old paints can contain chemicals that can prevent new coats of paint from sticking.
If the old paint is oil-based, it’s best to use a chemical remover or TSP to remove all traces of it before applying water-based paint over Polyurethane. If you can’t find a remover for this type of paint, you could try using a heat gun.
Useful Precautionary Tips when Painting Over a Polyurethane
Paints, primers, and even wood surfaces all contain hazardous chemicals; therefore, before you begin your painting job, remember to take a few precautions:
- Protect yourself – always wear a face mask, goggles, and gloves when painting. This will help to protect your skin, eyes, and lungs from any harmful chemicals that may be in the paint.
- Protect your surfaces – lay a drop cloth or plastic sheeting over any protective surface you want to protect from paint splatters. This will also help to keep your work area clean.
- Open windows and doors – to avoid any fumes from building up in the room, open windows and doors to allow fresh air to circulate.
- Turn off the air conditioner – to avoid blowing those fumes all over your house, turn off any air conditioners that could bring them inside.
Is priming needed before painting Polyurethane?
Yes, it is always a good idea to prime before painting Polyurethane. Priming new surfaces will ensure that your paint sticks and provides maximum protection against humidity exposure. It can also add brightness to colors on new or sun-bleached wood.
NOTE: It is very important to use a primer specially designed for type of paint you are using otherwise it won’t work well or result in peeling.
Can I Paint Over Polyurethane Without Sanding?
No, you should always sand Polyurethane before painting. Sanding will help create a smooth surface that can easily accept paint.
Sanded surfaces also dry faster than unpolished ones, which is especially important if you plan to apply more than one coat of paint.
TIP: If the surface has not been sanded in the past year, you may need to use more aggressive sandpaper to remove any built-up residue.
Can You Spray Paint Over Polyurethane?
Yes, You can spray paint over Polyurethane. This method is especially useful for large surfaces that require a quick and even coat of paint. You can buy it either in oil-based or water-based versions.
If you are using oil-based spray paint, it is important to sand the surface first so that the paint will stick. If you are using water-based spray paint, a coat of primer beforehand is needed in addition.
TIP: You can buy special spray paints where priming is not needed or included in the product formula.