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How to Thin Acrylic Paint?

how to thin acrylic paint

Whether you are a beginner or an experienced artist, the process of thinning acrylic paint can be quite burdensome if you are unsure how to do it. Basically, the acrylic paint thinning process involves adding water or another medium to acrylic paint to make it dissolve slowly. The result is a thinner paint with a lighter viscosity and consistency.

It is important to learn how to thin acrylic paint, especially if you think it is necessary due to the highly thick and viscous paint. The entire process can provide different consistency, effects, and colors. In fact, thinned acrylic paints often resemble watercolors.

While the entire process of thinning acrylic paint looks easy, it is kind of hard to achieve your desired results and effects if you don’t receive proper guidance and experience. Fortunately, this article is now around to enlighten you with the process and ensure that you are doing everything correctly.

Step-by-Step Guide

So what to use to thin acrylic paint and achieve your preferred effects? Learn about that and the steps involved in the next section.

Using Water

using water

What You Need:

  • Distilled water
  • Acrylic paint
  • Paint palette
  • Palette knife or stirring stick
  • Paintbrush


Step 1 – Add water in small amounts initially

The first thing to do is to add distilled water to the paint but only in small amounts first. Add more water slowly and only if needed. Avoid adding excessive amounts of the liquid immediately as it may result in the acrylic paint becoming too thin that it is already hard to work with.

As a guide, stick to the 1:10 ratio when adding the distilled water. This means that the water should be just one part while the paint should be ten parts of the mixture. Mix well with the help of a palette knife or stirring stick.

Distribute the water evenly throughout the entire paint. Did you decide to use a paint palette? Then you have the option to mix the water and paint directly on your palette. However, if what you are using is a container, you have to move the paint into it first prior to mixing.

Step 2 – Test consistency

After combining water and paint, you can start testing the consistency of the mixture. You can do that by dipping the paintbrush into it first and then putting it on a scrap canvas or paper.

You will know that the consistency is already right if the paint flows evenly and smoothly from the brush. There should not be any streaks or clumps left. Correct the consistency by checking whether the paint is either too thick or thin.

For acrylic paints that have become so thick, adding more water can help. However, if it has become too thin, more paint should be added to the mix.

Step 3 – Continue making the necessary adjustments

As you proceed with using the thinned paint for your artwork, you may notice its consistency changing. The changes may occur when the acrylic paint starts drying on the palette or as you continue adding layers to the artwork.

Again, you have to check the thickness and thinness of the paint. More water is necessary for paint that ends up becoming extremely thick while more paint should be integrated into the mix when it turned out to be too thin.

Acrylic Medium

using acrylic medium

Thinning out acrylic paint is also possible by mixing it with any acrylic medium. One benefit of using an acrylic medium is that it is capable of retaining the acrylic binders’ integrity, which means that your desired coverage will still be attained regardless of the amount of medium added.

It is likely for the acrylic paint to thin out and turn out to be even more transparent as you keep on adding the medium. In addition, the medium is the key to making the acrylic paint remain on the support or canvas’ surface, thereby maintaining the glossy finish.

Another reason why you should use an acrylic medium to thin the paint is it can make the whole process easier and hassle-free. You don’t have to think thoroughly about the perfect ratio as well as the possibility of the paint peeling eventually. With that, it works perfectly for beginners.

To give you an idea, here are the specific acrylic mediums you can use in thinning acrylic paint:

  • Airbrush medium, which has almost the same level of thinness as water – It can also give a smooth application.
  • Pouring medium
  • Acrylic binder
  • Flow improver, which is kind of costly and seems to work only for expert and professional artists – This acrylic medium produces a stain effect while being effective in performing its function of improving the flow of paint.
  • Fabric medium, which helps in making the paint ideal for clothing

Using these acrylic mediums is also easy. Let’s take the airbrush medium as an example in learning the steps involved in thinning acrylic paint with it.

Step 1 – Put the airbrush medium into a container.

Step 2 – Add the paint. This simple step will let you have a thinned and smooth paint immediately.

If you use an acrylic medium, it is unnecessary for you to think of a ratio or percentage as you blend. This is beneficial as this means that the paint has a low chance of peeling off the surface.

With the thinning medium around, the paint will bind to the surface. Expect it to serve as the primer for several layers of paint, too.

Glue and Water

using glue and water

Thinning acrylic paint is also possible if you use glue and water. This is particularly helpful for pouring paint. It helps improve the fluidity of the paint while being easy to control and manipulate so it can handle different pouring techniques, like puddle pour, swipe, and flip cup.

What Do You Need:

  • Acrylic paint
  • Water
  • White glue
  • Stirring tool, like a wooden stick or palette knife
  • Mixing container


Step 1 – Prepare your chosen area

Pick a spot with proper ventilation. Add a protective covering to the surface to ensure that splatters or spills will not occur. Do the necessary preparations, too, by wearing protective gear, like a smock, gloves, and an apron. This helps prevent paint from staining your clothes.

Step 2 – Mix in the acrylic paint

The acrylic paint is the one that should be added next to the glue mixture. Add tiny amounts first then mix into the glue. Keep on stirring this mixture. Put on more paint slowly until your desired consistency and color are reached.

Step 3 – Mix the glue solution

In this step, you will have to mix the glue with water. The ratio for this will greatly depend on you and your desired level of consistency. As a rule, you can mix one part each of glue and water if you prefer to have a thin consistency. If you have a measuring tool, you can also use it in obtaining accurate and correct ratios.

Step 4 – Mix well

With the help of a stirring tool, like a wooden stick or palette knife, mix the glue solution and paint well. Keep on stirring until it forms a smooth mixture free of any clumps or lumps.

Step 5 – Monitor the consistency

Of course, you have to retain the paint’s consistency. In that case, the brush can be dipped into the mix and then tested on a piece of canvas or paper. More water is needed for extremely thick paint and more glue or paint for solutions that do not receive your preferred consistency.


With a few solutions on how to thin acrylic paint integrated into this article, you don’t have to worry too much about how your painting will appear. If the acrylic paint gets the appropriate consistency, expect it to be able to give an artwork a more professional finish.

Read more: How to Rehydrate Acrylic Paint