Mixing Latex Paint With Polyurethane (Here’s What To Avoid)

Mixing different types of paint is a common practice, especially with latex paints. But can you mix latex paint with polyurethane?

You can mix latex paint with water-based polyurethane because they use the same paint solvent (water). However, you can’t mix it with oil-based polyurethane because of the different paint solvents. 

Mixing them is done to give the finish color tint. Being a clear coat, polyurethane doesn’t have paint pigments on its formula; this means its finish has no color and is transparent. So, if you mix these two paints, you will get a durable colorful finish. 

Compatibility

You can’t mix oil-based polyurethane with latex paint because they have a different paint solvent (base). Latex paint uses water as its paint solvent, while oil-based polyurethane uses natural or synthetic oil.

Both of them dry when their solvent fully evaporates from the coating, and the coating becomes hard. Since water evaporates faster than oil, latex paint dries faster than polyurethane. So, they have different drying times. 

If you mix them, the mixture won’t dry properly or at the same time. Some parts (spots) of the mixture will fully dry, while the other parts will still be wet. This leads to a cracked finish.

Also, the flow of the mixture will be inconsistent since oil and water don’t mix. So, you must avoid mixing latex paint with oil-based polyurethane. Only mix it with water-based polyurethane. 

How To Mix Latex Paint With Polyurethane?

Mixing latex paint with polyurethane isn’t hard. But, you need the right steps and tools to do it.

Here are the tools you need:

• A Can Of Latex Paint
• Water-based Polyurethane Finish
• A Clean Bucket
• Water
• Paint Mixer Or Turning Stick
• A Measuring Cup

1. Pour Both of them Into a Clean Bucket.

Pour the required amount of water-based polyurethane into a clean bucket. You can use a measuring cup to measure how much you are pouring. 

Water-based polyurethane must be poured into a clean bucket first. That’s because you are tinting polyurethane and not the other way around. If you pour latex first, the water-based polyurethane will act as a paint thinner and thin it.

2. Add Latex Paint

You must mix them in a ratio of 2:1 (2 parts polyurethane to 1 part latex paint). If you don’t want a bright finish, use 1/2 part of latex instead of 1 part. 

The main purpose of the paint is to give polyurethane a colorful finish. The mixed polyurethane will have the same color shade as latex. So, use paint with a color shade you want the finish to have. Due to the clear coat finish of the sealant, the mixture will have a brighter color than the original paint. 

If you want to mix two or more colors of latex paint, mixing the paints first in a different container is better. Once you mix them, apply the mixture to the polyurethane bucket and mix them again.

3. Stir The Mixture

Once you add the paint and the sealant to the bucket, mix them. 

To stir the mixture: 

1. Use a paint mixer or turning stick,
2. Ensure the turning stick touches the base (bottom) of the container while stirring. 
3. If you use a turning stick, stir for 15 minutes. If you use a paint mixer, stir for 5-7 minutes.
4. You can add drops of latex paint to the mixture while stirring. 
5. Once the paint has a consistent color and flow, stop stirring. 

4. Test The Paint Mixture

You must test the mixture on a dispensable item first. Testing will show if the mixture has a consistent flow and color and if it dries.

Using a paintbrush, apply the mixture to cardboard. If the mixture doesn’t dry, turns sticky, or has inconsistent color, you must re-mix it or add more latex paint. If the mixture dries properly and has a consistent color shade, you can use it. 

Applying Polyurethane Over Latex Paint

You can apply polyurethane over latex paint to increase the durability of the finish. Latex paint being water-based, doesn’t have a moisture-resistant or durable finish. So, you must seal it to increase its durability. 

When dry, polyurethane forms a glossy moisture-resistant finish. This glossy finish will protect the paint from moisture, water, scratches, and damage. 

Sealing indoor painted surfaces is optional. However, sealing outdoor surfaces is necessary. That’s because the paint isn’t formulated with additives that protect its finish from outdoor weather elements. You can use any type of polyurethane to seal it. 

Applying Latex Paint Over Polyurethane

You shouldn’t apply latex paint over polyurethane. That’s because polyurethane has a glossy finish that repels liquid, including paint. So, if you apply it, the paint won’t stick and will turn tacky.

The paint must penetrate a surface to stick. But, since the sealant forms a glossy layer that repels paint, latex won’t stick over it. Also, the sealant has a slick finish, meaning the paint will slide off without having time to stick. 

The type doesn’t matter; latex paint won’t stick over water-based, oil-based, or exterior polyurethane. The only way to apply it over a sealed surface is to sand the sealant or remove it completely, then apply the paint.

Final Words

You must mix latex paint with water-based polyurethane only. That’s because they have the same paint solvent (water), so they are compatible. The best way to mix them is to use a ratio of 2:1.

You shouldn’t mix latex paint with oil-based polyurethane because they use different solvets (oil and water), so they aren’t compatible.