How to Thin Acrylic Paint

Co-authored by Kelly Medford

Acrylic paint is a medium commonly used by artists. You can thin acrylic paint to achieve differences in consistency and color, allowing you to attain effects that would have otherwise been impossible. These can range in appearance, with some thinned acrylics imitating the look of watercolor or even oil painting. All you need are some basic thinning techniques, an understanding of how to revitalize hardened paint, and some methods for painting with acrylics.

Part 1

Part 1 of 3:

Thinning Your Acrylics with Basic Techniques

1
Apply a small amount of paint to your palette. You might also use a mixing container, like a bowl or plastic container. Keep in mind that acrylics dry in 10 - 30 minutes, with professional grade acrylics often taking longer to dry than student grade. As this is a quick-drying kind of paint, using too much from the tube can result in expensive waste. To avoid this, always start with a small amount, adding more on an as-needed basis.^{[1]
X
Research source}
2
Add water to your paint. When only thinning your paint slightly, take your brush and wet it in clean water. Too much moisture can leave your acrylic paint looking thin; too little may not have much of an effect at all. To significantly thin your paint, pour water into a container with your paint and use your brush to mix the water and paint together.
- Be sure you thoroughly distribute the water throughout your acrylic. Failing to do so can result in clumping or an uneven color.
- Have paper towel on hand for blotting brushes once you are ready to begin painting. Too much moisture on your brush, or too much remaining moisture after you've cleansed your brush of a previous color, can severely thin your paint, which can lead to drips forming in your painting.^{[2]
  X
  Research source}
EXPERT TIP

Kelly Medford
Professional Artist
Kelly Medford is an American painter based in Rome, Italy. She studied classical painting, drawing and printmaking both in the U.S. and in Italy. She works primarily en plein air on the streets of Rome, and also travels for private international collectors on commission. She founded Sketching Rome Tours in 2012 where she teaches sketchbook journaling to visitors of Rome. Kelly is a graduate of the Florence Academy of Art.

Kelly Medford
Professional Artist

Use water or a gel medium for different results. Gel gives the paint more body, but it also makes the paint more transparent. Water makes the paint thinner, but it can also make it washy and runny.

Advertisement
3
Mix in a thinning or anti-congealing agent. You can use one of these substances in place of water for a more controlled thinning of your paint. You can buy ready-to-use thinning/anti-congealing agents at your local art store. These will keep your paint from drying out too fast and thin it in the process. Always add your thinning agent according to its directions, but generally, you should apply your agent in small amounts using your brush.^{[3]
X
Research source}
- The composition of each of these thinning agents will likely react differently depending on the kind of acrylic paint you are using. It's best if you add your agent little by little, until it has the desired effect.^{[4]
  X
  Research source}
4
Check the consistency with your palette knife. You should have a section of spare canvas or a surface on which you can check the consistency of your paint. As you thin your acrylics, you'll find tint and thickness also change. Take your palette knife and spread paint after adding your thinner to check if the consistency is as desirable as its hue.^{[5]
X
Research source}
5
Add gesso to the paint and water mixture. Gesso is a primer for the painting surface. It makes acrylic and oil paints adhere better to canvases and other surfaces. But you can also use gesso to thin and extend the paint, tinting your paint slightly with the color of the gesso.
- You can add gesso by stirring it in with your paint using a clean paintbrush. Using gesso with water or another thinning agent may cause your paint to become too thin.^{[6]
  X
  Research source}

Part 2

Part 2 of 3:

Revitalizing Hardened Acrylic Paint

1
Identify paint you can save. If your paint has hardened completely, it won't be possible for you to revive it.^{[7]
X
Research source} However, paint that has thickened and has become firm but is still somewhat tacky or malleable can often be restored. You can gauge your paint with a poke from your finger or a tap from your brush or palette knife.^{[8]
X
Research source}
- For paint that is especially solid, press onto it firmly with your finger, the handle end of your brush, or your palette knife. If you notice an indentation form, this is a good sign that you may be able to revitalize your paint.^{[9]
  X
  Research source}
2
Use a palette knife to revitalize stubborn acrylic paint. If you notice your acrylic paint has begun to solidify, you may still be able to bring it back to a workable state. Add water or a thinning agent and firmly mix it into your paint with a palette knife. Make sure you have a good grip on your palette before attempting this; this may take some extra oomph, and accidentally knocking your palette on the ground can create a big mess.
- You may find it easiest to set your palette down on a sturdy surface before attempting this. You should still maintain a good grip, as the smooth surface of your palette will be prone to slipping or sliding as you grind at the paint with your palette knife.^{[10]
  X
  Research source}
3
Use grinding motions for especially hard paint. If your poke check has revealed that your paint, while significantly hardened, is still malleable, you may not be able to revitalize it by mixing it as you would conventionally. In these cases, you should grind your palette knife to mix water into the hardened paint on your palette.
- This motion will force the water throughout the thicker, hardened parts of the paint. If after some minutes you notice no difference in the consistency of your paint, it is likely too dry to revitalize.^{[11]
  X
  Research source}

Part 3

Part 3 of 3:

Using Thinned Acrylic Paint

1
Know the limitations of your chosen acrylic. Art supplies can be very expensive so, when starting out, you'll likely want to use student grade paints. These will be most affordable, but will also offer less coverage and greater shift in color as the paints dry.^{[12]
X
Research source} Artist grade (professional) acrylics, on the other hand, have higher levels of pigment, a wide array of colors, and limited color shift when drying.
- Student grade acrylics are not necessarily less useful or desirable than artist grade paints. Student grade paints are excellent for large scale projects or any under-painting you may have to do.^{[13]
  X
  Research source}
2
Understand the constraints of the media. Beyond the well-known fact that acrylics dry quickly, there are many other considerations you should be aware of when choosing your acrylic paint. Generally, you can expect that acrylic paint not fully dry can be revitalized by water, but it will not be able to be rehydrated after it is fully dry.
- This is important to take into account, because if you plan on using a color-lifting technique, as you would with watercolor paints like gum arabic, it will not work with acrylics. Once the acrylic has been used in a wash and dried, you will not be able to rehydrate the paint.
3
Practice creating your target tint or effect. Acrylics can give the appearance of many different styles. You can use your acrylics to create artwork that resembles watercolors or even more elaborate oil paintings. This, however, will require experimentation on your part. Different paints are made from different ingredients, and these will all have unique properties.
- With experience, you'll likely begin to develop an intuition for how much a certain kind of paint needs to be thinned to achieve your desired color. To do this consistently, you should note the process you used when you achieve a particularly desired shade through thinning.
- One of the most common kinds of acrylic paints, and the one you'll most likely be painting with, has a satin sheen, also called a semi-matte sheen. Other finishes common in acrylic paints are gloss and matte.^{[14]
  X
  Research source}
4
Create acrylic washes you can paint over. If you thin your acrylic paint until it resembles the consistency of watercolor, you can apply this paint to your canvas to create a backdrop or scene. Once this acrylic wash dries, you can paint freely on to of it.
- In most cases, when an acrylic dries, it becomes water insoluble. This means that you can paint over your acrylic wash freely without worrying about paint running or the image becoming muddy.^{[15]
  X
  Research source}
5
Blend colors without hesitation.^{[16]
X
Research source} You may want to practice your color theory and the mixing of colors with inexpensive paints until you are confident in this. Acrylics dry so fast, so if you hesitate while blending your colors or take too long, your acrylics might harden before you can apply them to your canvas.
- You may find that you can prevent the drying process by using a dampened piece of paper or card stock when blending. Don't forget to mist your paints if you are using a plastic palette.^{[17]
  X
  Research source}
6
Use tape to create sharp contrast edges. Acrylic paint is great for layering, especially because once it dries it isn't easily affected by moisture or other applications of paint. If you plan on painting over an acrylic wash or background, you can create high contrast edges by putting a piece of masking tape where you want the sharp edge.
- The masking tape will keep the paint underneath protected from the second application of paint. Masking tape also has little risk of ripping paint free once you are ready to remove it from your painting.^{[18]
  X
  Research source}

Community Q&A

Question

Does folk art acrylic paint have a shelf life? I haven't used in many years and don't know if I can add something to revitalize the many bottles I have.

Community Answer

As long as the paints are still in fluid form, you can just add water to thin them, then use as usual.
Question

Do I need to add water to acrylic paint if you don't want it to look like a watercolor?

Community Answer

No, acrylic paints do not need water added, but some artists add water for a watercolor look/feel or for a thinner paint consistency.
Question

How do I make lines with thin acrylic paint?

Community Answer

Best approach is to use painter's masking tape. Use two strips and set them side by side with the opening between them the width of the line you want. Best way to apply the acrylic paint is by using an airbrush. Apply quick thin coats with it and let them dry between applications for a few minutes until you get the depth of color you are seeking.