How do you clean a watercolor sponge properly (and how to keep it clean)

Knowing how to clean out a watercolor sponge can be tricky. You should do this regularly, otherwise your sponge will build up bacteria and affect your paints. Let me show you how to do this.

Each time you use your watercolor sponge, you need to wash it with warm water to keep it clean. Most of the pigments, minerals, etc. are removed this way. To prevent mold from growing on your sponge and affecting your health, you should clean it every now and then with a vinegar and salt mixture.

watercolor painting equipment on a table

How do you clean a dirty watercolor sponge?

You can easily take care of your watercolor sponge after you have finished painting with it by simply rinsing and cleaning it with warm, flowing water.

The water ensures that leftover water, pigments, minerals, and dust are flushed out of the sponge.

Warm, flowing water is essential for this process. Due to the temperature, bacteria that has built up in the sponge will most likely be killed. 

Instead of using a bucket or something similar, I like to use flowing water to ensure I get all the pigments, minerals, etc. out of the sponge and not let it soak in it.

Let the sponge dry completely on a towel after you press all of the water out. Leaving this step out will likely result in mold growing over time, making your entire process pointless.

If you’d like to find out, if watercolor paints have an expiration date, find out by reading this article.

woman painting with watercolor

The 4 steps to keeping your watercolor sponge clean forever

Step 1: Clean the sponge after each use

This is the most important step. You should build a habit of not only cleaning your sponge after each use, but also your other supplies.

This will save you a lot of money and headaches in the long run.

If you leave your sponge where it is, maybe even soaking in paint water, more bacteria will grow over time.

Eventually, the sponge might become moldy and harmful to your health.

Additionally, your paints will be dirty, and you won’t be able to apply them in their true colors.

As a rule of thumb, you should always clean your sponge after every painting session. While it doesn’t take long, it goes a long way.

Step 2: Clean it properly

I mentioned this earlier, but it is important to not just rinse it under water, but really clean it. 

It doesn’t take long at all, perhaps 1-2 minutes.

Take a look at the first topic of this article and follow the steps.

Step 3: Let it dry on a towel or newspaper

When you are finished cleaning your sponge, you should let it air dry on a towel or newspaper.

Newspaper isn’t as efficient at absorbing water and could tear a bit, leaving small pieces of paper on the sponge, so I prefer using an old towel.

Ultimately, it’s just important to let it dry on a dry surface. This will prevent bacteria and mold growth.

Press out as much water as you can so there isn’t much left to dry.

Step 4: Deep clean it regularly

Generally, just washing your sponge with warm, flowing water will suffice.

However, I do recommend deep cleaning your sponge once or twice a month.

Also, this usually doesn’t take more than five minutes. That way, it will live a long, happy life without bacteria or paint pigments remaining in it.

I recommend using brush soap or something similar to deep clean your watercolor sponge.

It’s usually used for brushes, as its name implies, but it also works for sponges.

Spread a little of that brush soap onto the sponge, then clean it with warm, flowing water for about a minute while wringing it out constantly.

Let the sponge dry on a towel again after repeating this process.

As a result, you can be sure that the sponge is as clean as new.

A vinegar salt mixture would also work well for deep cleaning. Due to the possibility of vinegar scent remaining, I prefer to use brush soap. 

If you’re unsure, if watercolor can actually grow mold, I would recommend reading this article, I’ve put together on the topic.

watercolor with a watercolor swatch and a flower

How often should a watercolor sponge be cleaned?

You should clean your watercolor sponge after each use, as I just mentioned. So far so good.

Cleaning a watercolor sponge before every use makes sense in many cases as well. Let me explain.

When you don’t use your sponge and let it lay around, it will collect dust over time.

Then after a while you’ll use it and your paints will have all that dust in them, which could ruin the experience of painting and the paint itself.

As a result, I would suggest that if you only use your sponge every few weeks, you should clean it as I mentioned in the beginning.

Rinse it under warm, flowing water. Even though it takes only 30 seconds, this little step before painting can greatly improve your painting experience.

I recommend storing sponges in a sealed, small space, like a plastic box with a lid, to avoid sponges accumulating dust.

Are you unsure, if watercolors can actually go down the drain? You can find out here.

How NOT to clean your sponge

Many people like to use bleach, alcohol, or some kind of cleaner to clean their sponges, such as kitchen cleaner.

I would hardly advise against these kinds of techniques since they will only damage your sponge and therefore your watercolor paints.

Bleach can be especially detrimental to a watercolor palette, even if it is applied indirectly.

I mentioned earlier that it’s sufficient to use a sponge or brush cleaner designed for this purpose.

Other cleaners can damage the sponge and the paper you use it on.

If you’d also like to learn how to clean brushes properly, you can find an in-depth tuturorial here.

And if you’d like to find out if watercolor paintings can be laminated, check this post out.


Watercolor sponges should be rinsed and wrung out after each use with warm, flowing water. Use a brush soap every two to four weeks to make your sponge even cleaner. Never use bleach, alcohol or any kind of household cleaner as they will damage your sponge, paints, paper, and therefore your painting experience.

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