How to Thin Latex Paint? (For a Sprayer or Paint Brush)

Latex paint has a thick flow, and thick paints are hard to apply. However, thinning the paint makes it lighter and easier to apply. So, how to thin latex paint?

You can thin latex paint by adding water to the paint in a ratio of 1:4 (1 part water – 4 water latex paint). 

While thinning, you must have more latex paint than thinning compound (water) to prevent an inconsistent paint shade of the latex paint. After adding the thinning compound, you must stir the mixture for 5 minutes until it has an even consistency and color. 

However, you can’t thin latex paint with mineral spirits or thinning compounds containing oil. That’s because oil and water don’t mix well and can ruin the latex paint finish. 

Formula To Thin Latex Paint

You must thin latex paint in a ratio of 1:4 (1 part thinning compound, 4 parts latex paint). You can also use another formula of 1/2 cup of water to 1 gallon of latex. So for 2 gallons of latex paint, you will need 1 cup of water (or 236 milliliters).

To spray the latex paint, you must thin it more. That’s because the latex paint needs to be lighter to come out smoothly from the sprayer nozzle. However, if you want to apply the latex paint with a paint roller or paintbrush, you don’t have to thin it as much.

You can also find the right ratio to thin latex paint by checking the paint container. Most paint brands include the thinning ratio on the paint can. 

While thinning, you must add the thinning compound to the latex paint, not the other way around. This means pouring latex paint into a paint bucket first, then adding the thinning compound. This way, you can monitor the color and flow of the latex paint. If you add the latex paint to the thinner, you risk over-thinning the latex paint.

Thinning Compounds For Latex Paint

What Can You Use To Thin Latex Paint

You can use different paint thinners and solvents to thin latex paint. This is because latex paint is water-based and, as such, can be mixed with different types of solvent without repelling the solvent. Let’s check out some common paint thinners and find out if you can use them to thin latex paint.

Water

You can thin latex paint with water. Water is the most common latex paint thinner. That’s because latex paint uses water as its solvent, so if you add more water, the solvent amount on the paint increases and latex paint gets thinner.

However, you must add the right amount of water to avoid over-thinning the latex paint. As a rule of thumb, mix 1/2 cup of water with every gallon of latex paint. 

Denatured Alcohol

You can use denatured alcohol to thin latex paint. But, you must use a small amount to thin the latex paint. That’s because denatured alcohol contains alcohol in high quantities, and alcohol can separate the paint pigments from the binder.

So, only use denatured alcohol to thin latex paint if you are experienced. 

Paint Thinner

You can use water-based paint thinner to dilute latex paint. However, you can’t use oil-based or petroleum-distilled paint thinner to thin latex paint. 

If you thin latex paint with oil-based paint thinner or turpentine, you will ruin the paint flow and color shade. The finish will look messy and peel off if you use latex paint that has been thinned with oil-based paint thinner.

So, only use water-based paint thinner for latex paint. 

Mineral Spirits

You shouldn’t use mineral spirits to thin latex paint. That’s because mineral spirits contain natural oils from trees and petroleum, and oil and water-based paints (latex) don’t mix well. 

If you thin latex paint with mineral spirits, you will ruin the color and viscosity of the paint. This will make it difficult for the paint to stick, dry, and stay on the material. 

Lacquer Thinner

You shouldn’t use lacquer thinner to thin latex paint. That’s because lacquer thinner is designed to thin lacquer paint, not latex paint.

If you thin latex paint with lacquer thinner, you risk separating the paint pigments with the thinning compound. This is because lacquer thinner is made of solvents like acetone. Acetone is meant to thin the oils and pigments in lacquer stain and not latex paint.

How To Thin Latex Paint?

Thinning water-based paint isn’t hard, but you must use the right type and amount of thinning compound. 

Here are the tools you need:

  • Water-based paint thinner or water
  • A paint mixer or turning stick
  • A paint bucket
  • Rubber gloves
  • Latex paint
  • Clean rags

1. Open and Pour The Latex Paint

Open and Pour The Latex Paint

First, you must pour the latex paint into a clean paint bucket. So, ensure that the paint bucket is clean, and if there’s any paint residue, especially oil-based paint, you must remove it as it can affect the flow and color of the latex paint. 

You can also dilute latex paint inside its container, but it’s better to use a large clean paint bucket because you have more space to work with.

Pour the needed latex paint into the paint container. But, measure the amount of latex paint you used because you need it to calculate the right amount of paint thinner to add. 

2. Add The Needed Paint Thinner (Water)

Measure and Pour The Needed Amount of Paint Thinner

To thin latex paint, use water. But, before adding water to the latex paint, you must measure the water you need.

To thin latex paint for a sprayer, add 1/2 cup of water to 1 gallon of latex paint. To thin latex paint for brushing or rolling, add 1/4 cup of water to 1 gallon of latex paint. 

You must thin latex paint more if you use a sprayer because sprayers can’t apply thick paints. To use a spray gun, the latex paint must be as thin as possible without affecting the paint color. Paint rollers and paintbrushes can apply thicker paints.

If you want to avoid brush marks, use Floetrol instead of water. Add 4-8 ounces of Floetrol to a quarter of latex paint. 

Latex paints have different flows based on the brand and type of latex paint. So if you add the required amount of water to the latex paint, but it doesn’t seem enough, you can add more. But, be careful not to over-thin the latex paint.

4. Stir The Mixture

Stir The Mixture Thoroughly

After you add water to the latex paint, you must stir the mixture of both.

To stir latex paint:

  1. Use a paint mixer or a turning stick.
  2. Stir the mixture (latex paint and water) for 5 minutes or until the paint has an even flow and color.
  3. While stirring with a turning stick, ensure to press at the bottom of the paint container so the bottom of the paint mixes too. 

If you can notice the water flowing on the latex paint, it means you still need to stir. You have to stir until you have an even color.

5. Test The Latex Paint

Test The Latex Paint

You must test the thinned latex paint on a dispensable surface, such as cardboard or paper plaster. If the thinned latex paint has imperfections after it dries, it means you added too much or not enough water to the paint. Therefore, you must thin latex paint again and re-test it.

If the thinned latex paint has a consistent flow, dries well and fast, and the finish is smooth, you can use it. 

If You Over-thin Latex Paint:

If you over-thin latex paint, four things will happen.

1. The Paint Color Will Get Lighter

The color gets lighter when you add too much water or paint thinner to the latex paint. So when the paint dries, you get a lighter shade than you bought.

This can also make it very difficult to seal or cover existing paints on the surface as paint bleed-through will be evident. In simple terms, over-thinning latex paint gives you a lighter shade of color.

2. The Paint Won’t Stick Well

If you over-thin latex paint, the latex paint will have more solvent than binder or paint pigments. This makes it difficult for the paint to stick even to a well-primed surface. As a result, paint adhesion will be weak, and the paint will peel off eventually.

3. You’ll Experience Runs and Drips

If there’s too much solvent (water) in the latex paint, the paint will lose its viscosity and thickness. So, when you apply the paint, it will drip on the floors, especially if you apply it on a vertical surface (such as a wall). 

4. It Will Dry Too Fast

Since over-thinned latex paint has a lighter flow, the paint will dry fast — too fast. This means the paint particles won’t harden properly, and the paint won’t be durable. 

Related Read: Latex Paint Dry Time?

Final Words

You can thin latex paint with water or water-based paint thinner. However, you must use the right amount of paint thinner to avoid over-thinning. 

A good rule of thumb is to use a ratio of 1:4 (1 part water, 4 parts latex paint) to thin latex paint. Or, add 1/2 cup of water to 1 gallon of latex paint. 

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