Runny Paint – 5 Easy Fixes to Watery Paint Problems

how to fix watery paint

One issue with painting is that it might not be mixed properly.

If the paint is too runny, you will have to thicken it. Otherwise, the paint will not be thick enough to adequately cover the surface.

This also means that you will see what’s underneath.

Depending on what you are trying to accomplish, runny paint may ruin your attempts at creating an artistic work.

Reasons, why your paint can go runny, are…

  • When you keep emulsion, latex, or acrylic paints setting around for an extended period of time
  • When you leave enamel or oil-based paints unused for a long which will create a layer of oil that looks like water
  • The longer you allow the paint to sit, the more is paint supposed to be watery

Many times the new paint you have just bought can also be watery.

And this can be due to the reason that the paint store you have bought the paint from has not stored it properly in appropriate conditions.  

So, if you do not want to go your expensive paint wasted, let’s find out what different things you can do to make your paint a bit less watery…

How to Thicken Watery Paint?

To properly thicken the paint, there are several methods you can try.

One of the simplest is to simply stir or shake the paint in the can or container.

If it has not mixed properly, stirring it will combine the thicker paint elements with the water and provide more consistency.

However, if this does not work you may consider tossing out the paint if it has gone bad.

Whatever you choose, I am sure that your ultimate goal is to fix the paint that has gone bad by achieving the right consistency.

1- Toss Out Bad Paint

Bad paint is paint that can no longer be adequately mixed with water.

The elements that make up the paint have aged to the point where no technique will mix them with water properly again.

There are different reasons why paint ages or decays, but the most important is time.

Latex and water-based paints can last up to a decade if the cans have not been opened.

Once opened, they can last up to 2 years if properly sealed and stored in a cool, dry place.

Oil-based paints can last even longer, up to 15 years if the cans are unopened.

However, once opened oil-based paint will only last about a year.

However, before you toss out the paint because it is too watery, there are several more techniques to try before ditching the paint.

After all, paint is expensive and if there is a way to save it, it is worth the effort.

This means trying some inexpensive and sometimes free methods to add more consistency to the paint.

How to Thicken Watery Paint

2- Shake or Stir to Change Consistency

This is the simplest and easiest to fix reason as to why your paint is too watery.

As mentioned before, if the paint is not mixed properly, then the elements separate into thicker and thinner blobs.

Dip your brush into a thinner paint blob and it’s probably mostly water.

To fix the issue, put the lid back on the can and secure it tightly.

Then, shake the paint can back and forth briskly for about a minute.

This will mix the water and paint elements more evenly.

Alternatively, you can also use a long wooden stick to stir the paint for a few minutes until it has reached the proper consistency.

Either method works quite well, and it should be tried first before you attempt another technique.

If you have paint stored in a bottle, then introducing BBs or mixing balls into the bottle and shaking it can even out the elements.

3- Add Some Paint Thinner

This may seem counterintuitive at first, but if you are working with oil-based paint the thinner may solve the watery paint problem.

The thinner will reduce the thicker elements of the paint so they are more consistent.

To successfully use paint thinner, you’ll need to do the following.

  • Put the paint into a disposable container.
  • And one part thinner for every three parts of paint.
  • Mix the paint using a stirring stick for about a minute or two.
  • Test the paint by brushing it on a nearby surface.

Add some more thinner – if the paint is still not at the right consistency.

And remember that this will not work with water-based paints.

4- Use Hydroxyethyl Cellulose to Thicken

If you are using water or latex-based paints, hydroxyethyl-cellulose (HEC) will thicken it rather quickly.

This is a substance that will help reduce the amount of water present.

As a thickening agent, you can add what is needed to make the paint the consistency you desire.

  • Pour the paint into a larger container.
  • Add a little hydroxyethyl cellulose and stir it.
  • Inspect the mixture and if it needs more, add it.

Keep in mind that the amount of hydroxyethyl cellulose should not exceed ¼ of the total amount of latex paint.

Otherwise, the mixture will be too thick regardless of its consistency to work properly.

An additional benefit of using this product is that it will bring out the color even more.

Remember, oil-based paint is different than water-based.

This means that you should first try to add more layers or coats of paint first.

This will let you see if the watery or runny nature of the paint prevents it from properly sticking to the surface.

Try painting a few layers in a small area first. If that does not do the job, then you can try to thin the paint. 

5- Add Paint Drying Elements

A dry element or medium will help to dry out a water-based paint so it will become thicker.

The three main dry elements are also quite cheap and can be easily found.

Marble dust, pastes, and sand are excellent drying elements.

Just add them in small amounts to the paint and stir.

Once you get the desired consistency, test it out on a small surface area.

Then start painting in earnest once you are satisfied.

However, these dry elements may give the paint a texture that you do not desire.

Be sure to check it out first on another surface.

Signs Your Paint Has Gone Watery

In general, watery or liquid consistency problems are seen in older paints that are left unattended for months.

Fortunately, there are a few signs that will help you know that your paint has gone watery and that you need to take proper steps to fix the bad paint problem.

In most cases you will be noticing:

  • A gummy or highly viscous liquid under the deposited “skin” of the paint
  • Stirring the old paint does not work in getting the desired consistency
  • A stale, sour, or smell like rotten eggs, when you open up the can of paint

When you have tried all these methods and they still do not work, then toss the paint out.

It is either too old or too compromised to work properly.


Is watery paint bad?

No, that’s not always the case. Sometimes it can be bad but other times you can fix the watery paint problem and can reuse the paint successfully.

But that does not mean that paint is supposed to be watery. Especially when you are thinning the paint, you should do that in a proper ratio so that the paint does not get watery.

Can you thicken the paint with the joint compound?

You can indeed thicken your watery paint with a joint compound.

However, you should be aware that this will also change the color of the paint slightly.

If you are looking to achieve a specific color, it is best to mix in a small amount of joint compound until you reach the desired consistency.

Keep in mind that the drywall mud and joint compound will also add a bit of texture to the paint.

So, if you need to thicken your paint for wall textures, it’s a great option to use.

What can you add to tempera paint to make it thicker?

There are a few things you can add to tempera paint to make it thicker.

One option is to mix in some flour or cornstarch.

Another option is to add in some heavy cream or whole milk. You could also try adding in some modeling clay or Play-Doh.

Many people have also used different household things such as salt, sugar, and even sawdust to thicken paints in the past. Maybe you can try them.

Finally, you could try using less water when you mix the paint. Experiment with different thicknesses to see what works best for your project.

The Bottom Line

Allowing the water to evaporate in the water-based paint is by far the simplest way to make your paint thicker.

Just leave the paint outside in the air for a few hours and you are good to go.

However, this method won’t work always.

If you need to fix your runny paint faster try adding household thickening agents or compounds like HEC.

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