How to Thicken Acrylic Paint: Tested Methods

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Anyone who has worked with acrylic paints knows that the paint should be neither too thick nor too thin. There are actually times when you would want your paint to be thicker, such as when working on leather and some types of canvas.

But, there may come a time when you are working with acrylics and you find that your paint is too thin or it has gotten a bit soggy. You won’t be able to create texture in your paintings, and the colors would look dull. What do you do when this happens?

Some people would simply throw the paint away and get new paint. I think this is a complete waste of money when it is so easy to thicken paint yourself.

Today I am going to talk about thickening acrylic paint with ingredients you may already have in your pantry (as well as a few you may have to purchase from an art supply store).

Why Does Acrylic Paint Become Runny or Watery?

Watery paint happens when the acrylic paint separates from the water while it is in the tube or bottle. This often happens when the paint has become old or expired.

Generally, acrylic paint is good for about three to five years once it has been opened. After that, it can be touched and go as to how it will perform. Paint that has not been opened will last for about eight to 10 years.

Another reason why your paint may be watery is the temperature of the room where it is stored. It should be in an airtight container and stored in an area where the temperature is between 18 and 24 degrees Celsius. It can also become watery if it is stored in a wet or humid area.

The container that your paint is in can also play a role in whether or not the paint becomes watery. Ideally, your paint will be in tubes. Paint that comes in bottles tends to be of a lower quality, to begin with, and it is going to be more watery right from the get-go.

What Do You Need to Use to Thicken Acrylic Paint?

Ideally, the best thing to use to thicken acrylic paint is by adding gel or paste medium. These are both available at most art supply stores.

Adding one of these mediums will allow you to use thicker brush strokes, which will add more texture to your acrylic paintings. The medium will also add flexibility and sheen to the paint, as well as luminosity.

Thickening medium can be poured or molded, and it is relatively easy to use. You can even increase the thickness of watercolor paints with these mediums.

If you don’t have one of these mediums, you can also use cornstarch or talcum powder to thicken your acrylic paint.

How to Make Acrylic Paint Thicker

As I already mentioned, you can use cornstarch and talcum powder to thicken acrylic paints. You can also use a joint compound. I have even known some artists who use regular baking flour for this purpose.

If you are looking to save money, I suggest trying either of the methods I am going to discuss here. Chances are you already have cornstarch in your pantry, and you may also have talcum powder, especially if you have children.

#1. Thickening Acrylic Paint with Cornstarch

The least expensive method I know of to thicken cheap acrylic paint is by using cornstarch. Not only is this less costly than purchasing mediums, it is super-easy to do.

All you need are two tablespoons of cornstarch and a cup and a half of water. Combine these ingredients in a saucepan.

Place the pan on the stove, and “cook” over medium heat until the solution thickens. I also use this recipe (with different measurements) to thicken berries for strawberry pie!

Once the mixture has thickened to a consistency that is much like ketchup or a bit thicker, remove the pan from the heat and allow the mixture to cool.

Start thickening your paint by adding a small amount of the cornstarch mixture and mixing until it is well-blended with the paint. You can add more later if your paint is still not thick enough. Once you reach the desired level of thickness, your paint is ready to use.

#2. Thickening Acrylic Paint with Talcum Powder and Joint Compound

You can also use talcum powder or joint compound to thicken acrylic paint. Typically, a joint compound is used to seal and fill joints. You will find it in most hardware stores, and it is relatively inexpensive.

The only drawback to using a joint compound is that there is no guarantee about the longevity of your paint. But, it does give the paint a lovely finish!

If you are going to use a joint compound, all you need to do is mix a bit of the compound into the paint. I suggest using a little bit at a time until you reach your desired paint consistency.

You can do the same thing with talcum powder. Mix the talcum powder with a bit of water to create a paste. When the paste is the desired consistency, you can then mix it into the acrylic paint.

Using talcum powder will give you more of a matte finish. So, if you want a glossy finish you will need to varnish your paintings, which you should be doing anyway to protect them.


Just because your paint may be a bit on the watery side, there is no reason to get rid of it, at least not just yet. Try using one of the methods I have talked about today to thicken your paint to get more life out of it.

Thick paint is great for painting on leather and some types of canvas. You spend a lot of money on your paints and other art supplies. It only makes sense to do as much as you can to preserve those supplies so you can use them, again and again, many times before having to replace them.

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*image by Nik_Merkulov/depositphotos