Mixing different types of paint is a common practice especially while working with latex paints. But can you mix latex paint with polyurethane? Here is the answer to that.
Latex paint and polyurethane finish can be mixed but both paints must have the same base or solvent. This means latex paint can only be mixed with a water-based polyurethane finish.
Mixing latex paint and polyurethane finish is done to give the polyurethane a color tint. Polyurethane like most other clear topcoats doesn’t have color. So latex paint pigments can be mixed with polyurethane to tint the polyurethane finish.
But that’s not all. There is more to know about mixing latex paint and polyurethane and this post digs right into the topic. Let’s dive in.
Can Oil-Based Polyurethane Be Applied Over Latex Paint?
Oil-based polyurethane can be applied over latex paint because latex paints don’t have any glossy sheen that prevents inter-coat adhesion. But before you can put oil-based polyurethane over latex paint, the latex finish must be sanded lightly.
It’s also advised to use an oil-based primer on the latex finish after sanding. This is because oil-based polyurethane and latex paint have different bases and features which makes them react differently to changes.
The varying bases and features of latex paint and oil-based polyurethane will not allow perfect bonding between both paints.
Also, the finish will begin to turn yellow after a while. So priming with an oil-based primer is usually advised before applying oil-based polyurethane over latex paint to improve paint bonding and durability.
Oil-based primers will adhere well to latex surfaces. The primer will improve the bonding between the oil-based polyurethane and latex paint. Priming also helps to fill the tiny pores in the latex finish that can suck the polyurethane finish.
Applying oil-based polyurethane over latex paint helps to preserve and beautify the latex finish. Dried polyurethane is strong and moisture resistant.
The polyurethane serves as a shield to protect the latex paint against factors that can cause chipping. The oil-based polyurethane finish also beautifies the latex paint by giving it a glossy and reflective appearance.
However, it is better to use water-based polyurethane over latex paint. This is because water-based polyurethane has the same base and similar features as latex paint. So, durability and paint adhesion is guaranteed even without priming first.
Though oil-based polyurethane can be applied over latex paint, latex paint can’t be applied over oil-based polyurethane.
This is because polyurethane when cured forms an ultra-thick and glossy sheen. That sheen prevents any water-based or latex paint grime from adhering to the polyurethane surface.
Related Read: Can You Apply Latex Over Oil-Based Paint?
How To Mix Latex Paint With Polyurethane (In 5 Easy Steps)
Mixing latex paint with polyurethane isn’t a difficult task. But it can quickly become messy if the paints are mixed carelessly.
As an expert tip, only mix latex paint with a water-based polyurethane finish. Never mix oil-based polyurethane and latex paint. This is because both paints have different features and bases.
Oil-based polyurethane has lots of chemicals, natural or synthetic oils, and volatile organic compounds (VOCs). Latex paints on the other hand have a very low level of active chemicals and are water-based.
Mixing latex paints and oil-based polyurethane is a very bad idea. You can only apply oil-based polyurethane on latex paint that has cured, been sanded, and primed with an oil-based primer.
To mix latex paint and water-based polyurethane, you need the following tools:
- A Can Of Latex Paint
- Water-based Polyurethane Finish
- A Clean Bucket
- Paint Mixer Or Turning Stick
- A Measuring Cup
Here is how to mix water-based polyurethane and latex paint:
- Open The Paint Containers
- Pour The Water-Based Polyurethane Into A Clean Bucket
- Measure The Latex Paint
- Add and Stir The Latex Paint With The Water-based Polyurethane
- Test The Paint Mixture
Now, let’s get to work.
1. Open The Paint Containers
The first step is to open the lids on the latex paint and water-based polyurethane. Both paints have a low level of active chemicals so the paints might not produce a strong smell of chemicals when you open them.
This doesn’t mean the paint is bad. It just shows you that both paints are water-based. Oil-based polyurethane will release a strong chemical smell when opened.
2. Pour The Water-Based Polyurethane Into A Clean Bucket
The required amount of water-based polyurethane should be poured into a clean bucket or container. You can use the measuring cup to measure the required amount of water-based polyurethane. If you intend to use all of the polyurethane, you can pour all of it into the bucket.
Don’t pour the latex paint into the bucket before adding the water-based polyurethane. This is because you are trying to tint the polyurethane and not the other way around.
If you put the latex paint in the container first, the polyurethane will act as a paint thinner. What you’ll get is diluted latex paint and not a colored polyurethane.
3. Measure The Latex Paint
After you have poured the polyurethane into a clean bucket, measure the needed amount of latex paint. The advised ratio is to mix 2 parts of polyurethane with one part of latex paint.
You should add enough latex paint that will give you the type of finish you are looking for. If you want a thin finish, then you’ll need just a small amount of latex paint. If you want a thicker or brighter finish, then you’ll need more latex paint.
You should know that water-based polyurethane has no color. So the color of the latex paint that you pick is the color tint that will be produced after mixing.
If you want to mix two or more different colors of latex paint with the water-based polyurethane finish, it’s better to mix the latex paints first in a different container. Then add the required amount of the mixed latex paints to the water-based polyurethane finish later.
4. Add and Stir The Latex Paint With The Water-based Polyurethane
When you have the required amount of latex paint, add it to the water-based polyurethane inside the bucket. Then stir both paints. You can stir using a paint mixer or turning stick.
If you aren’t sure about the required amount of latex paint to add, you can add drops of the latex paint while stirring. Continue adding drops of latex paint while stirring till you arrive at the required paint thickness and color.
Ensure to stir both paints till there is color uniformity and paint consistency. This means stir till it’s almost impossible to notice that you mixed paints.
When both paints look and feel the same, then you have successfully stirred. Now, you are ready to test out the mixture.
Related Read: Can You Put Epoxy Floor Over Existing Paint?
5. Test The Paint Mixture
Using a paintbrush or spray gun, test the mixture on a surface like cardboard. You can also test the mixture on a small part of the item you want to use the paint on. Then let the paint mixture dry.
If the paint mixture is easy to apply, then that’s a good sign. When the paint dries, you should have a uniform application and a bright color on the surface.
If you achieve this, then you have successfully mixed the latex paint and water-based polyurethane.
Now, you are ready to paint.
Can You Apply Polyurethane Over Latex Paint?
You can apply polyurethane finish over latex paint. Both the oil-based and water-based polyurethane can be applied over latex paint. But water-based polyurethane adheres and lasts longer on latex paint than oil-based polyurethane.
However, before you can apply polyurethane over latex paint, the latex finish should be clean and lightly sanded with a fine-grit sandpaper.
The latex finish should also be primed using the required primer for the polyurethane finish. Here is a guide on which primer to use for which type of polyurethane finish.
The latex paint should be primed with an oil-based primer when using oil-based polyurethane. And, the latex paint should be primed with a water-based or latex paint primer when using water-based polyurethane.
Sanding is necessary for both types of polyurethane finish. But, priming isn’t necessary for water-based polyurethane on latex paint.
This is because both water-based polyurethane and latex paints have the same base so adhesion is not a problem. However, priming will improve the resulting finish of both types of polyurethane.
Since you can apply polyurethane over latex paint, can you apply latex paint over polyurethane? Let’s take a closer look.
Related Read: How To Apply Polyurethane Over Old Polyurethane?
Can You Apply Latex Paint Over Polyurethane?
You shouldn’t apply latex paint over a polyurethane finish. This is because polyurethane is a glossy finish that prevents inter-coat adhesion. When polyurethane dries, the resulting finish is glossy and slick. Latex paints cannot adhere or stick to glossy or slick surfaces.
So if you put latex over polyurethane, the finish will come off within days due to improper bonding.
However, there is a hack to painting latex over polyurethane. To do this, you have to properly sand and remove the glossy top sheen of the polyurethane finish.
When the glossy top sheen is removed, the polyurethane will then be primed using a water-based primer or latex paint primer.
When the glossy top coat has been removed and the surface has been primed, then you can apply latex paint over it. But this is a tedious, time-consuming, and unnecessary process for many reasons.
For starters, polyurethane especially oil-based polyurethane is designed to be glossy. So to remove the top glossy sheen will most likely mean to remove the whole polyurethane finish. Doing this will expose the surface underneath to moisture and scratches.
Also, removing the top coat of the polyurethane finish isn’t advised unless you want to apply another clear coat finish on the poly.
If you strip off the glossy sheen of the polyurethane and paint over the polyurethane with latex paint, the whole paint job will be uneven. Not to mention the fact that latex paint is not as durable as polyurethane.
By removing the top gloss of the polyurethane finish, you are exposing the entire paint job to moisture and scratches which the latex paint is not capable of preventing.
Related Read: Can You Use Chalk Paint Over Latex?
Will Polyurethane Protect Latex Paint?
Polyurethane finish will protect latex paint by making the latex paint more resistant to factors that can damage the latex. Like moisture, dust nibs, and scratches. Polyurethane when dry forms an ultra-thick and protective topcoat that shields the latex paint underneath from moisture and chipping.
Also, polyurethane beautifies the latex finish by giving the latex paint a reflective and glossy appearance. Applying polyurethane over latex paint will make the latex last longer.
Latex paints are not very durable. This is because of the water-based and thin nature of the latex paint. Latex paints are easily affected by moisture and scratches which cause the paint to chip or peel eventually.
But when the latex paint is sealed with a polyurethane topcoat, the polyurethane protects the latex paint by making it resistant to factors that can damage it.
How Long Should Latex Paint Dry Before Applying Polyurethane?
You should wait until the latex paint has cured before applying polyurethane over it. It takes between 24 hours and 72 hours for latex paint to cure enough for polyurethane application.
If polyurethane is applied over latex paint that hasn’t cured, the entire finish will look amateurish. The latex paint underneath will turn white because moisture is trapped in the paint pigments.
The polyurethane finish applied over the latex will also not bond well because the base coat or latex coating underneath hasn’t cured.
You can expect the finish to discolor and peel off in weeks if the latex paint didn’t cure properly before polyurethane was applied to it.
Latex paint dries very quickly. Provided all painting conditions are met, it takes about an hour for latex paint to dry enough to touch. But this doesn’t mean you can apply polyurethane over it just yet.
The paint has to cure before polyurethane coating can be applied over it. This means the solvent has to be completely evaporated from the paint pigments so the paint can harden.
The reason the latex paint has to cure completely before applying polyurethane over it is because of the process of applying the polyurethane.
Before the polyurethane is applied, the latex paint will be sanded and primed. If the latex paint is not strong enough to handle being the sanding and priming process, it will come off especially while sanding it.
But if the latex paint is strong enough, it can be sanded and primed without any problems and the polyurethane will sit on it well.
Related Read: Should You Apply Enamel Paint Over Latex?
Overall, you shouldn’t mix latex paint and polyurethane paint except both paints have the same base. If the paints have different solvents or bases, mixing them will ruin both paints and make them unusable. This is due to the varying chemical makeup of both paints that will clash when mixed.
However, you can apply both oil-based and water-based polyurethane over latex as long as you sand and prime the latex paint first.
But you shouldn’t use latex paint over polyurethane regardless of the base or solvent. Latex paint doesn’t just stick well to polyurethane.