How to Thin Water-Based Paint for Spray Gun


Last updated: June 2, 2023

Get expert tips on how to thin water-based paint for a flawless finish.

A picture of spray gun demostrating - how to thin water based paint for spray gun

If you’re planning on using a spray gun to paint your next project, you’ll need to know how to thin water-based paint for spray gun. 

Water-based paint is a popular choice for indoor and outdoor projects because it’s easy to clean up and has a low odor. However, it can be thicker than other paint types, making it difficult to spray with a gun. 

This article will show you how to thin water-based paint for a paint sprayer. We’ll also cover the tools and materials you’ll need, the right paint-to-water ratio, and pro tips for a smooth and even application.

Let’s get into it!

How to Thin Water – Based Paint For Spray Gun

Start by stirring the paint in the can to ensure a smooth, creamy texture. Next, strain the paint into an empty bucket and gradually add 1 part water to every two parts of the paint. Stir the contents in the bucket to mix well. Test for the right consistency using a viscosity cup.

What Are Water-Based Paints?

These are a type of paint that uses water as the primary solvent. This means that the pigments are suspended in a water-based solution rather than a solvent-based solution.

Water-based paint is a popular choice for indoor and outdoor projects because it’s easy to clean up, has a low odor, and is more environmentally friendly than oil-based paints.

This type of paint is available in acrylic and latex formulations, each with its advantages and disadvantages.

Acrylic paints are more durable and resistant to fading and peeling, while latex paints are easier to clean up and have a less harsh odor.

Even though water-based paint is suitable for a wide range of applications, it’s unsuitable for colder exterior temperatures. It also doesn’t adhere that well to oil-based paint.

When To Use Water-Based Spray Paints?

Water-based spray paints are ideal for various surfaces, such as wood, vinyl, metal, masonry, and more.

These paints are also best used for projects that require a smooth and even application, such as painting walls, trims, furniture, and cabinets.

Additionally, water-based paints are less toxic and more environmentally friendly than their oil-based counterparts, making them an excellent choice for any DIY project.

Why Do You Need To Thin Water-Based Paint For Spray Gun?

Water-based paint is thicker than other paint types, making it difficult to spray through a gun. When the paint is too thick, it will clog the gun’s nozzle, resulting in an uneven application.

Thinning the paint allows it to flow through the gun more efficiently, resulting in a smooth and even application.

Additionally, thinning the paint helps to reduce the risk of clogs and paint buildup.

What is the Ratio of Paint to Water?

The ratio of paint to water will vary depending on the type of paint and the type spray gun you’ll use.

As a general rule, you should start with a ratio of 1 part water to 2 parts paint water and adjust as needed.

However, too much water can weaken the paint’s adhesion and lighten the pigment. Therefore, starting with a small amount is best and adding more as needed.

An excellent way to determine the right paint’s consistency is to use a viscosity cup. This tool measures the paint’s viscosity and helps you achieve the correct consistency for your paint gun.

How Do You Thin Water-Based Paint for Spray Guns

Thinning water-based paint for a spray gun requires diluting the paint with water to a certain degree.

Now that you know the correct ratio, keep reading to learn how to properly reduce the paint’s thickness.

What you will need

  • Bucket
  • Paint stir stick
  • Spray gun
  • Water
  • Water-based paint of choice
  • Funnel/ viscosity cup

Water-Based Paint Thinning Procedure.

Step 1: Open the Paint Can and Mix the Paint Thoroughly.

Be as thorough as you can if the paint has been sitting in your garage for a while. Otherwise, give the paint a gentle stir if you recently purchased it from the shop and it has already been through a mixer.

Step 2: Pour the Paint Into the Bucket.

Transfer the amount you need into another container or gallon bucket. Try not to pour more than you require because the paint will thicken again if left idle for too long.

Step 3: Slowly Add Water to the Paint.

Use a funnel to add water slowly to avoid splashing the paint around. Stir the paint and water mixture with the paint stir stick.

Use a quarter cup of water each time and stir. This specific volume of water allows you to thin the paint without overdoing it and spares you the trouble of going back and forth with adding more paint or water.

Step 4: Stir the Paint and Water to Mix Well

Use a stir stick or a paint mixing blade to stir the paint until it is thoroughly mixed and has a smooth consistency.

Step 5: Test the Paint’s Viscosity.

The paint’s thickness will affect the results, so it’s essential to test it out beforehand. 

One way to do this is to pour the paint through the funnel spout into the paint bucket; it should flow freely through the funnel.

Alternatively, you can use paint stir stick to test the paint’s consistency. Stir the paint and lift the stick a bit; if the paint runs off the stirring stick in a continuous stream, it is thin enough.

However, if the paint runs off in thick globs or sticks to the stick, you need to thin it further.

You can also check the paint’s thickness using a paint sprayer. Transfer the paint to the paint sprayer and spray it on some cardboard or other material. You’re good to go if the thin paint sprays effortlessly and evenly.

However, if the paint lands on the substrate and forms fish eyes, bubbles, or sprays unevenly, pour it back into the bucket and thin the paint further. Repeat this process until the paint flows freely through the gun.

Once the paint has the correct consistency, it is ready to create magic with the spray gun.

How to Thin Latex Paint for HVLP Spray Gun

Latex, water-based paint has a thick consistency that would be impossible to spray before thinning. When thinning latex paint for spraying in an HVLP (High Volume, Low Pressure) spray gun, the same principles apply as when thinning regular water-based paint.

  1. Start with the standard ratio: The general rule of thumb is to mix 1 part paint with two parts water. This can also translate to 20-30% water for every gallon of paint.

  2.  After each addition of water, stir the paint and water to mix well.

  3. Test the thinned paint on a sample surface to check if it has the right consistency. Use the viscosity or paint sprayer to check for the right latex paint consistency. 

  4. If the latex paint is still too thick, add more water to thin it out to the desired consistency.

Some brands of latex paint may require different thinning ratios to get the right texture. This then necessitates you check the packaging instructions before you thin latex paint.

How to Thin Water-Based Paint for Spray Gun

How to thin acrylic paint for a spray gun

Thinning acrylic paint for use in a spray gun is a relatively simple process. It is important to use the correct ratio of paint to the reducer to achieve the desired results.

First, you will need to get clean water that you’ll use to reduce the thickness of the acrylic paint.

Next, stir the paint using a stir stick to mix the pigments evenly. Transfer the amount of paint you need for your project into a clean bucket.

Then, gradually add water to the gallon bucket while stirring gently. You’ll most likely use one part of water for every two parts of paint. However, add more water if it’s necessary.

Stir the mixture vigorously for a few minutes to ensure a consistent texture. Run the paint through a viscosity cup to check if you’ve achieved the right thickness or thinness.

Try the spray gun test if the acrylic paint passes the viscosity cup test. Pour the paint into your spray gun and spray it on some cardboard. If you like the paint coverage and the speed at which it flows, you’re ready for your spray painting project.

Pro – tips when thinning water-based paints

Here are some tips to remember during and after you thin your paint:

  • Always start with only a small amount of water to the paint and gradually add more until you reach the desired consistency.
  • Stir the mixture thoroughly after each addition of water to ensure a consistent mixture.
  • Make sure use clean water to avoid introducing impurities into the paint.
  • If the paint has been sitting for a while, you may need to add more water to restore its viscocity.
  • Use a high-quality paint strainer to remove any lumps or debris from the paint.
  • Use a viscosity cup to determine the correct consistency of the paint for your gun.
  • Test the paint by spraying it through the gun on a scrap piece of material before applying it to your project.
  • Lastly, always store unused paint or dispose of any waste properly.

FAQs – How To Thin Water-Based Paint For Spray Gun

Do You Need To Thin Water-Based Paint For a Sprayer?

Yes, you need to thin water-based paint before using it in paint sprayers. Water-based paints are thicker than most paints and would struggle to pass through a sprayer nozzle. That’s why it needs to be thinned to a correct viscosity for easy and consistent paint spray results.

Can You Thin Water-Based Paint With Mineral Spirits?

No, you should not. Only use water when you want to thin your water-based paints. Mineral spirits are potent paint thinners best used to thin oil-based paints. Adding mineral spirits to water paints will definitely affect the texture and adhesion of the paint.

What is The Best Spray Gun For Water-Based Paint?

The Wagner Control Spray Max HVLP sprayer is an excellent option for water-based paint application as it provides a smooth and even finish. It uses high-volume, low-pressure technology to atomize materials into fine particles. The pressure from the cup supplies paint to the gun to make it easier to spray paint walls and other surfaces.

Can You Thin Water-Based Paint With Acetone?

No, we advise against using acetone to thin water-based paints. Acetone is a paint thinner for oil-based paints but a terrible thinning agent for your water-based paints. Using it will ruin the paint in many ways. For example, this solvent will weaken the water paint’s adhesion and mess up the texture, resulting in a terrible paint finish.

Can You Use Rubbing Alcohol To Thin Water-Based Paint?

Yes, you can use rubbing alcohol to thin water-based paints like acrylic and latex paints. This thinner can significantly speed up the paint’s drying time. While this can be a good thing, thinning the paint with more than 20% alcohol can lead to uneven paint results.

What Thinner To Use For Water-Based Paint?

Water is the best thinner to use for water-based paint. This dilutes all types of water-soluble paints, including latex and acrylic paints. You only need to add a little bit of water when thinning paint to reduce the thickness of the paint before application.

Wrapping Up On Thinning Water-Based Paint For Spray Gun

We hope you enjoyed our article on how to thin water-based paint for spray gun.

Thinning water paint for a sprayer is a walk in the park once you master the paint-to-water ratio. However, you can adjust the ratio to suit your specific needs. So grab your spray gun and give your project a fresh coat of paint.

Feel free to share this article with others who could use a refresher on thinning water-based paints. 

Still, if you want to use solvent-based paint, be sure to read our article on how to thin oil-based paint for the spray gun.

Happy thinning!

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