How to Use Water Brushes: Your Complete Guide

Water brushes (sometimes called water brush pens) are basically like travel paintbrushes, but are useful for much more than that! They’re a convenient, portable, and versatile art tool to have around your desk.

One might be included with a watercolor brush pen set because they work so well for blending water-based pens.

Water brushes are easy to use and fun to play with, but at first you may be unsure of how to start using one. In this guide, I’ll show you how to fill them, use them, and clean them.

Plus there are some ideas at the end of this post of how you could use one!

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What is a water brush?

A water brush is essentially a cross between a brush pen and a paintbrush.

They’re called “water brushes” because while they have paintbrush-like tips, the barrel of the pen is meant to be filled with water.

When the barrel is filled, you can apply pressure to the sides of the pen while holding it and water will come up and out through the brush tip.

With just a squeeze of the barrel, you get drips of water on the brush bristles to paint with. This way you can keep wetting the brush without needing a separate water container, and the bristles also stay continually moist as you use it.

Water brushes are very convenient because they’re so easily portable. Paintbrush and water are combined into one handy tool, making them perfect for painting outside or on the go.

These brushes come in different tip sizes, barrel sizes, and tips, as well as a few different pen types. Some types, like piston water brushes, are filled differently than others. (More on filling them below!)

Water brushes are primarily used for watercolor painting, although they can also be used with some other types of ink. Just be careful, since some can clog or ruin the brush.

I especially like to use water brushes for watercolor brush lettering and blending with watercolor pens.

Here’s a video of how I do that!

Related: How to Use Watercolor Brush Pens: Beginner’s Guide

What’s the difference between a water brush and a normal brush?

Water brushes can be used in place of regular paintbrushes, but they don’t perform exactly the same. 

The main differences between water brushes and other watercolor brushes include the following:

  • Water brushes are much cheaper than many watercolor brushes
  • They are also pen-sized, have lids, and are easier to carry than regular paintbrushes
  • It’s harder to control water with water brushes
  • It’s more difficult to do some brush techniques (like dry brushing) with a water brush
  • Water brush bristles are made of nylon, unlike regular watercolor brushes, so they are stiffer and don’t hold as much water
  • The selection of water brush tips and sizes is much more limited (they only come in round or flat tips)
  • Water brushes store water right inside the barrel, so you don’t need a separate water container like you would with regular brushes

Water brush pens can’t replace regular paintbrushes, but that’s not their purpose anyway. They’re a nice combination of a paintbrush and a brush pen, and very handy tools to have!

They’re great for using in sketchbooks, during travel, or for any quick watercolor project when you don’t want to get out brushes and water jars.

My pick

One of my most-used water brushes is the Sakura Koi water brush. I have the 9ml with a medium brush tip, but there are smaller or large sizes, too.

(Linked is the 9ml with a large brush tip, since the medium isn’t available on Amazon anymore.)

I use mine for watercolor lettering, water drop art, and blending water-based brush pens.

water brush pens

How to fill a water brush

The first step to using a water brush is to fill it with water!

Because there are a few different types of water brushes, the method for getting water into the brush varies a little.

I’ve only used the simplest kind of water brushes with an open reservoir, where you just unscrew the barrel and fill it.

Some water brushes have a plug at one end of the barrel when you unscrew it, and others have a piston to fill it with.

Here’s how to fill each kind of water brush:

  1. Basic: Unscrew the pen top section from the barrel. (Some unscrew clockwise.) Fill the barrel with water through the opening using a faucet or a dropper. Screw the top on securely.
  2. Squeeze waterbrush: Unscrew the pen top section from the barrel. Now you can either remove the plug from the barrel opening and fill it with water, or dip the barrel into a container of water and squeeze to fill it with water. Make sure the plug is put back in, and reattach the top section to start painting.
  3. Piston waterbrush: Unscrew the top section from the barrel. Dip the barrel into a container of water and pull back on the piston to fill with water. Screw the top back on, turn the pen upright, and slowly push the piston back in.

(For more detailed instructions on using a piston water brush, visit this JetPens product page and read the description.)

If you’re not sure which kind of water brush you have, just unscrew it and see which one of these it is.

Filling with ink or paint

It’s possible to fill water brushes with watery paint or ink instead of water, but it can also clog and stain the brush and be hard to fully clean out.

Paints seem to almost always clog the brushes if left inside, so some inks are more likely to work. According to JetPens, it’s best to use fountain pen inks in water brushes, not dip pen inks.

Once I filled one of mine with diluted blue watercolor paint and it worked fine for the short time that I used it, but much of the brush was left badly stained. 

I have also not been able to take the brush section pieces apart to clean it out, and I’m guessing it’s clogged with old paint.

If you like the idea of a refillable brush pen it could be fun to fill one with ink, but I’d recommend experimenting with a cheap one first before filling any more!

If you’re not sure whether something will clog/ruin the brush, clean it out thoroughly after using (instead of leaving it in the brush) and it should be fine.

painting with water brush

Painting with water brush pens

Here’s how to use a water brush for watercolor painting in simple steps!

  1. Squeeze the barrel to get the water flowing.

    Press the sides of the barrel until water drops out from the bristles so you know the water is flowing well. (Some have buttons on the side that you push.)

    The more you squeeze, the more water will drip from the brush. Squeeze just a little and wait for second, and a drop of water will just moisten the bristles.

  2. Add water to paint pans.

    To activate dry watercolor pans, squeeze a few drops of water onto the paint. Then you can pick the paint up with the brush and start painting!

    As you paint, you can squeeze out water whenever you need more, whether it’s onto your palette, paper, or paper towel.

  3. Clean the brush when changing colors.

    To clean the brush in between colors, squeeze out water while wiping it on paper towel until the water comes out clean. You could also rinse it in water like a regular paintbrush if you prefer.

  4. After using, shape the tip and let dry.

    Once you’ve finished using it, smooth the clean brush tip to a point and let it dry before putting the cap on to protect the bristles during storage.

For the most part, water brushes can be used just like regular brushes for watercolor painting. Depending on how much water you use, you may have to refill the pen more than once.

Sometimes water can drip or leak out from places other than the bristles as you squeeze it, so you might want to do it over something else to avoid messing up your artwork.

I recommend always keeping a rag or paper towel nearby so you can easily tap excess water off your brush.

How to clean a water brush

Caring for water brushes is fairly simple, but it’s recommended to clean them regularly to keep them – you know – clean.

To clean your water brush pen after a painting session, squeeze water out while wiping the bristles on a paper towel until the water comes out clean.

Water brush tips are prone to staining, so don’t worry if some color remains on the bristles after cleaning. It won’t affect your painting!

Every so often, you may need to do a more thorough cleaning if the brush isn’t flowing well, is very stained/dirty inside, or has been filled with something other than water.

To deep clean your water brush, you can usually take it apart and clean or soak the individual pieces. Just make sure to keep track of them so you know how to put it back together!

For most water brushes, you can take them apart in a few simple steps:

  1. Unscrew the top section from the barrel.
  2. Grip the bristles at their base and push them firmly inward. They should slide in and the entire inner part will come out from the top section.
  3. Remove the plug at the base of the bristle section. (Depending on the brush, the small plug may just fall out separately. Remember which way you need to put it back in.)
  4. Slide the bristles out of the plastic holder. (They’ll stay together since they’re attached at the base.) Don’t try to remove the little sponge since it’s delicate.
  5. After cleaning, reassemble the water brush as you found it.

To clean the individual parts, soak or rinse them in water. You’ll need a long cotton swab or small bottle brush to clean the inside of the barrel.

For a deeper clean, you can use dish soap, or a solution of vinegar or bleach, especially if you find algae or mold inside the brush.

The little sponge inside the top section gets pretty dirty and it feels good to squeeze it in water and get it clean again!

This YouTube video shows you how to take apart and deep clean a water brush.

Not all water brushes are easy to take apart, though, so if you can’t get yours apart don’t worry about it. Just clean what you can.

Two of mine don’t come apart, even with a pliers (which will damage the plastic), but one of them is clogged with old watercolor paint.

To keep your water brush as clean as possible, it’s best to clean it out fairly often. That said, I’ve never cleaned mine out before and it doesn’t affect how I use them (yes, I know I should clean them more).

blending with water brush
Using a water brush to blend watercolor brush pen ink.

Should I empty my water brush?

You may be wondering if it’s okay to leave water in your water brush for a long time.

If you use your water brush often, it’s fine to leave water in the barrel. (I always have…) I like to let the bristles dry before putting the lid back on.

But if you’re going to put it into storage or don’t plan to use it for a while, it’s best to empty it and let it dry to prevent algae or mold.

To do this, just unscrew the barrel, empty it, and let it all dry completely. You could take it apart further if you want to be especially thorough.

Once the brush is totally dry, you can store it however you’d like, put together or in separate pieces.

water drop art with a water brush

Ideas for using them

There are lots of fun ways to use water brushes, and they’re really handy to use in combination with other art supplies.

Because they are filled with water, they work best with water-soluble mediums like watercolor, gouache, or some inks.

Here are some ideas for using water brush pens:

  • Watercolor travel sets: They’re the perfect companion to a travel watercolor paint set. All you need is your paints, water brush, and a paper towel! You can get them in shorter barrel lengths to fit better into small travel kits.
  • Art journaling: Water brushes are perfect for outdoor nature journaling, sketchbook art, or any kind of art journaling because of the ease of having paintbrush and water combined in one lightweight brush. Add a quick wash of watercolor, fill in a sketch, or do some abstract art!
  • Water-based brush pens: Water brushes work very well with water-based brush pens and can be used in place of a colorless blender pen, too. Use the wet bristles to activate the water-soluble ink and blend colors together. I love using my water brushes to blend brush pen lettering for beautiful watercolor effects!
  • Watercolor pencils: Watercolor pencils are another fun and easy way to paint, and water brushes work very well with them. Just make marks with the pencils and blend them with your water brush.
  • Brush lettering: It’s a bit easier to do brush lettering with firm, nylon-tip water brushes than regular watercolor paintbrushes, so they’re perfect for doing lettering with watercolor paint or ink.
  • Water drop art: You may have seen videos of super-satisfying water drop art before. I’ve done it myself and it’s really fun to do! The easiest tool to use for this is a water brush pen. Put watercolor paint on the bristles and squeeze out colored beads of water onto paper. (The hardest part is not making a mess of all those droplets!)

Quick Tip

When using a water brush with watercolor pencils or brush pens, you can also pick color up directly from the pencil/pen tip with your water brush.

How long do water brushes last?

Water brushes will last a long time if you take care of them. I’d guess they could last as long as a regular paintbrush.

Obviously, it depends on how well you take care of them. Water brush tips could get ruined pretty easily.

Also, unlike regular brushes, they can get clogged and ruined if you use the wrong paint or don’t clean them.

So if you want your water brush to last a long time, it will – just take care of it!

I hope this guide was helpful and answered any questions you had about these pens.

Have you used a water brush? How do you like to use yours? Let me know in the comments below!

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