What Can I Add to Acrylic Paint to Thicken It Up?

It's not uncommon for an artist to complain about acrylic paint that is too runny. These paints vary from one brand to another and sometimes you will find one that is just too thin to work with. The question is, then, what can you add to thicken it up?

While you may be tempted to mix some normal household product into your paint, there are a few factors to consider. Let's explore why that ingenious paint hack may not work out as well as you hope.

The Problem With Paint Hacks

Artists will try just about anything when it comes to their paint. We also tend to be, shall we say, cheap. This leads us to brainstorm all sorts of ideas to troubleshoot issues with our materials. Trying to thicken acrylics is no exception.

To the frugal artist, it may make sense to turn to a common household product that is known for thickening things. Corn starch and flour are two that often come to mind. After all, they do a fantastic job when you need to thicken a sauce, right?

While it's true that things like that may very well seem like an inventive paint hack, we have to consider the long term ramifications. The primary concern here is the effect on the longevity of the paint. These hacks may work today, but you want your painting to last a very long time. Adding an unknown element will jeopardize the archival qualities of your paint.

In addition, you must also think about the workability of your paint with these non-traditional additives. Artist paints are made with a specific formula and, for acrylics, part of that determines how well it mixes with water.

Even though you're trying to thicken the paint, it's possible that you'll still want to thin it at times or add a wash on top of it. Adding water to an acrylic that has corn starch or flour may result in a hideous, slimy paste that may not be pleasant to work with.

The third and final consideration is the negative effect on the paint color itself. Paint hacks like this may alter the hue—turning a red into a pink, for instance—and this may happen immediately, as it dries, or anytime in the future.

The Best Way to Thicken Acrylics

That argument against DIY paint hacks should convince you to avoid them. But what can you use? The easiest answer is one of the acrylic mediums that are designed for this exact purpose.

To err on the side of caution, spend a little money on a texture gel or modeling paste. Be sure that it is one that works with acrylics because some mediums are formulated for other types of paint. These are made with the same resins and other ingredients that go into acrylic paints. It takes all of the concerns that we've discussed out of the equation.

Check the label to see whether the gel or paste will dry clear or opaque and whether it has a matte or gloss finish. It should also indicate if the medium will influence the color of the paint you mix it in. Some pastes look white, but dry clear; others have fillers in them that influence the intensity of the paint color.

Texture gels or pastes are water-based, so it's easy to clean up your brushes or painting knives after using it. You can either mix the texture gel with your paint or use it to build up texture first, then paint over it. There are also some that you can carve back into.

Various acrylic-paint manufacturers produce such pastes, with a price tag related to the brand. Something such as Winsor and Newton's modeling paste in their cheaper Galeria acrylic range may be a good place to start. You won't have to invest a lot of money, but you will gain experience in using it and see for yourself how it affects your paintings.