How to Soften Hard Watercolor Tube Paint

Did you accidentally leave the cap loose on your watercolor paint tube? Or maybe you just picked up a deal on old watercolors and they've dried up? While watercolor paint in tubes is great to work with, all is not lost when they dry up and harden.

Unlike oils and acrylics, it is easy to reactivate watercolor paint. It is the nature of the paint - the fact that it requires water - that makes it one of the easiest paints to salvage. Don't throw away those tubes, there's a solution.

When Watercolor Paint Tubes Harden

Many painters prefer the quality and workability of watercolor paint in tubes. Unlike pan watercolors, they are not bone dry. This makes tube paints easier to mix into custom colors and allows you to begin painting right away. 

The bad news is you can't soften watercolor paint in a tube once it's dried hard. It will not have the ability to squeeze out of the tube like it used to. The good news is that this doesn't mean you can't use the paint, it simply means that you have to use them as you would your pan paints.

Dry Watercolor Fix No. 1: Just Add Water

Dry watercolor paint is not the end of the world. The glycerin that is added to tube watercolors has dried up and you are, essentially, left with dry pan watercolors. Before you can add water to reactivate the paints, you have to get it out of the tube.

If the paint has thickened but can still be coaxed out of the tube, squeeze or scrape it onto a palette. It will dry slowly on the palette ​but remain usable like a watercolor pan. Unlike acrylics, watercolor paint remains water-soluble when dry, so you can always "reactivate" it with a wet brush. 

1. Cut open the tube so you can access the paint. Take care not to cut yourself on the tube.
2. Use it in the tube by adding water (try to fold the edges of the tube so you don't have any sharp edges that'll damage the hairs on a brush). Alternatively, move the dry paint to your palette well, an old ice cube tray, or a similar tray where you can wet it and use it for painting as needed.
3. Use the paint like you would a pan or block of watercolor. That is, gently rub a wet brush onto the dried paint and allow it "dissolve" into the water. 

Tip: When moving dry watercolor to a new well, get it thoroughly wet with water, stir it, and allow it to dry again. This allows it to form to the new mold and all you have to do is add water when it's time to paint. When rewetting the paint, give the water a few minutes to react with the paint before painting.

Dry Watercolor Fix No. 2: Add Glycerin, Gum Arabic, or Honey

If you're determined to get the paint into a tube-like consistency again, there are a few common additives that you can try.

• Grind up the hardened paint with a glass muller (a compact tool used to grind pigments when making your own paint) and mix it with a few drops of gum arabic. Some artists use an old coffee grinder or mortar and pestle if they do not have a muller.
• Add and mix in glycerin, a few drops at a time, until the paint gets to a consistency you like.
• Honey is an old-fashioned additive to watercolor paint binders and may be used like glycerin. It may not, however, be the best idea if you enjoy painting outside as it may attract bugs.

If you work the dried paint enough, it should come back to a consistency similar to its original state. Then again, it may never be as smooth as the original, but a granular or gritty paint can be useful for textures like sand or rust.

Also, if you choose to reconstitute all of your paint at once rather than using it as a pan watercolor, make sure to place it in an air-tight container. If you don't it will just dry out again.