How to Thicken Latex Paint


Last updated: September 1, 2023

A Detailed Guide by Expert Painters on How to Thicken Latex Paint Like a Pro!

How to thicken latex paint

Have you ever started painting only to realize your latex paint is not sticking well onto your surface? 

Well, you probably didn’t do anything wrong. Your latex paint may just be too thin, and that’s why it’s not sticking as expected. For latex paint to work effectively and produce a smooth, professional finish, it must have a certain degree of thickness and consistency.

In this blog post, we’ll walk you through various tips and tricks on how to thicken latex paint to attain the desired consistency and give you a hassle-free painting experience. 

Why Is My Latex Paint Watery?

Latex paints, also referred to as acrylic paints, may become watery due to a longer storage period, exposure to extreme temperatures, or storing with an open lid as Latex is a water-based paint. Also, adding excess water or inadequately mixing the paint before applying might cause thinning.  Watery paint may also have gone bad or be too old.

Can I Make My Latex Paint Thicker?

Yes, you can make your latex paint thicker and achieve your desired consistency. You can do this using commercial paint thickeners or some household agents you probably have at home already. 

Stay with me as I let you in on some of the most effective methods of thickening latex paint and how to go about the whole process. 

How to Thicken Latex Paint

Ready to make your latex paint thicker before embarking on your paint job? Here are five of the most effective techniques that painters use to thicken latex paint:

  • Expose to evaporate.
  • Using drywall joint compound.
  • Adding Hydroxyethyl cellulose(HEC)
  • Adding a latex extender.
  • Using acrylic emulsion.
  • Using household thickening agents.

Let’s explore how you can use each of these methods to thicken your latex paint (Some of these methods can also work well with oil-based paint):

1. Expose to evaporate

Latex is a water-based paint and one of the simplest methods for thickening it is through evaporation. It’s the cheapest thickening method since it employs a natural process to thicken paint.

  • After opening the paint tin, stir the paint well and leave it exposed in a well-ventilated area.
  • Wait for about an hour, then stir the paint again while checking the consistency.
  • Do this until you achieve the desired thickness, which might be after several hours.

During evaporation, there will be a reduction in the paint’s water content, making it thicker.

Note that this method may take a lot of time and requires a lot of patience. It’s, therefore, good to do it a few days before the actual painting day.

2. Add drywall joint compound

You can also thicken latex paint by adding a drywall joint compound. You can get this compound from your local paint store or a paint manufacturer.

Thickening paint using a drywall joint compound is simple:

  • Add the compound in small quantities, say a tablespoon, into the paint, each time while stirring thoroughly until you obtain the desired thickness.
  • If you have a drill with a paddle bit, you can use it to help mix it up thoroughly.

This thickening method is fast and saves a lot of time compared to the evaporation method.

The drywall joint compound is also suitable if you want to add some texture to your thicker paint.

3. Use hydroxyethyl cellulose (HEC)

Hydroxyethyl cellulose is another compound that many painters use to make their latex paint thicker before painting.

Most professionals prefer this method since it’s fast and has a high record of effectiveness. 

Here’s how to thicken latex paint using HEC:

  • Create a slurry by mixing water and HEC in the ratio of 6:1.
  • Let the slurry rest for about half an hour.
  • Pour the slurry slowly into the paint while stirring until it’s fully incorporated into the paint and gives desired consistency.
  • Let it sit for another half an hour before using the newly thickened paint.

HEC can also be used to thicken oil paint.

4. Add a latex extender

Did you know you can also thicken latex paint by adding a latex extender?

Like HEC and drywall joint compound, you can buy a latex extender from your local paint store or online stores like Amazon.

Before using, shake the latex extender properly, then mix it with paint in the recommended ratio while stirring thoroughly.

Other than thickening the paint, a latex extender helps to make the paint more resistant to chipping and flaking. It also improves its lifespan, so it can remain open for a longer time without getting thin and watery.

5. Use acrylic emulsion

Acrylic emulsion, even though not popular, is also an effective medium for thickening latex and acrylic paints.

Gradually add the acrylic emulsion to the paint while stirring until the consistency is thick and uniform as desired. 

Other than thickening the paint, acrylic emulsion helps to improve its adhesion, making it stick better to your surface.

6. Use household thickening agents

Sometimes, you may need to thicken your paint but have neither resources to buy a thickener nor the time to wait for evaporation. 

Believe it or not, you have some products in your home already that can do the same job. 

Some household agents you can use to thicken latex paint include: 

  • Salt.
  • Sugar.
  • Sand.
  • Sawdust.
  • Cornstarch.

For sugar, salt, sawdust, or sand, add small amounts gradually into the paint while starring until the paint thickens and achieves the desired consistency.

Other than thickening the latex paint, these products will make the paint coarse, which could be a desirable texture for some painting jobs.


Cornstarch is another cost-effective and environmentally friendly thickening agent used to thicken latex paint.

If you have some cornstarch at home, follow the steps below to make your latex paint thicker:

  • Mix and stir 2 teaspoons of cornstarch into a cup of cold water.
  • Separately boil another cup of water and pour the cold cornstarch mixture into the boiling water slowly as you stir.
  • Stir continuously until the mixture achieves a paste-like consistency.
  • Allow the paste to cool off then add it to the paint gradually while stirring until the paint gains a thick consistency.
  • You can add more paste depending on the amount of paint you plan to use for the project.
  • If some paste remains unused, don’t throw it away. Pour it in an airtight container and store it in a cool place away from direct sunlight.

Unlike other household thickening agents, cornstarch will make the paint smoother and suitable for surfaces that require a smooth, non-rugged finish.

This thickening agent can also be used to thicken oil-based paints.

Therefore, the thickening agent you use on your latex paint will depend on factors like available time and resources.

When to Thicken Latex Paint

Knowing when to thicken latex paint can save you a lot of hassle in the long run.

For instance, you know it’s time to thicken paint if it’s not giving the desired finish on your surfaces.

Also, you’ll need to thicken if the paint has been exposed to conditions that make it watery e.g., longer storage time, extreme temperatures, and uncovered lid. Additionally, you may have added too much paint thinner until you lost the consistency.

If you use latex paint that’s unusually thin, there will be dripping, splattering, and inconsistent coverage, which can be messy in the end.  

Best Latex Paint Thickeners

There are several ready-made latex paint thickeners you can buy from your local paint store on from online stores like Amazon.

However, before buying, you need to do a proper background check to ensure it’s the best for your paint type and your project.

Here are some of the best latex paint thickeners you can find on Amazon:

1. Latex Thickener – 16 Oz – Additive Thickening Gel

Latex Thickener Additive Thickening Gel is a high-quality latex thickener from Liquid Latex Fashions. 

When mixed with latex paint, it not only thickens the paint but also boosts its elasticity to make it resistant to tear.

Due to its gel-like nature, this thickener gives your paint the right consistency to ensure there’s no dripping or sagging while painting. The gel works seamlessly with the latex paint to ensure the paint retains its flexibility, color, adhesiveness, and durability even as it becomes thicker.

Latex Thickener is easy and convenient to use— simply pour it into the paint while stirring thoroughly until you achieve the right consistency

It’s suitable for applications that require thicker and more consistent paint, like reusable molding, masking, and art projects, among others.

Many paint professionals, DIYers, and paint enthusiasts use this paint thickener since it’s cost-effective, easy to mix, and saves a lot of time.

2. Liquitex Professional Medium, 237ml (8-oz), Liquithick Thickening Gel

Liquitex Professional Medium is another amazing latex paint thicker from the Liquitex store. 

It comes in a generous 237ml (8-oz) jar, which ensures that you have enough thickener to last through multiple projects.

This thickener has a smooth and creamy consistency, which makes it effortless to work with. The gel mixes easily with various latex paints, and it’s highly versatile, so you can control the level of thickness according to your preferences.

One of the standout features of this paint thickener is its ability to add texture and dimension to my paintings.

Due to the texture variation it brings to the paint, it’s the best for professionals or artists looking to explore dynamic latex painting designs. It also allows you to add texture and dimension to your artwork with ease.

Additionally, it gives latex paint an extended drying time, which is perfect for blending and detailing. 

3. 100ml Latex Thickener Gel

Trustleaf Latex Rubber Thickener is another good latex paint thickener you can find on Amazon. A 1-liter latex dipping rubber often accompanies it. 

This paint thickener also has a smooth and consistent texture, which makes it incredibly easy to mix with latex paint. It blends seamlessly to create a thick, creamy mixture.

Trustleaf Rubber Thickener has some quantity of ammonia hence, it should be used in a well-ventilated space with a free flow of air. 

The 100ml latex thickener gel can be used to thicken latex paint for different applications like molding, special effects, and masking activities. For these activities, the ratio of thickener used should be 5%.

This gel gives latex paint a good consistency while maintaining its durability, color, adhesion, and flexibility. 

Pro Tips for Thickening Latex Paint Effectively

Ready to start thickening your paint? Here are more pro tips to help you do a perfect job and achieve the most desired outcome with your latex paint.

  1. Thorough mixing: When thickening paint, always mix thoroughly using a paint mixer or a stick. This helps to prevent clumping of the thickener in the paint, which may cause uneven paint consistency.

  2. Add small quantities: Be careful to add the paint thickener gradually in small quantities while monitoring the pant consistency. You do not want to have over-thickened paint since it won’t relate well with your paint brushes.

  3. Paint texture: Know the desired paint texture before settling on the thickener. This is because some thickeners will affect the texture of the paint after thickening, which you may not want.

  4. Test the paint: Finally, before you start using the thickened paint on our project, do a sample test on a small area to ensure it has the thickness and coverage your desire.

FAQs – Thickening Latex Paint 

What can I use to thicken paint?

You can thicken your paint by exposing it to evaporate or adding commercial thickening agents like hydroxyethyl cellulose (HEC) and drywall joint compound. You can also use household thickening agents like salt, sand, sugar, sawdust, and cornstarch.

Does latex paint thicken over time?

No. Latex paint can get thinner if stored in an air-tight container for long periods. However, when exposed or stored without an air-tight seal, water evaporates from the paint, and it tends to thicken over time.

Do dry mediums affect the paint’s texture?

Yes, dry mediums like drywall joint compound, sand, salt, sugar, and sawdust give the paint a coarse texture. On the contrary, using a wet medium like HEC and cornstarch paste gives it a smooth texture that’s suitable for smooth finishes.

Can flour make the paint thicker?

Yes. Flour can thicken acrylic paint and leave it with a nice smoother texture. Add 2-spoonful flour to 1.5-cup boiling water, form a gel-like paste and let it cool off. Gradually pour the paste into the paint as you stir thoroughly until the paint achieves the desired consistency.

Final thoughts – Thickening latex paint

Thickening latex paint can be easy, fast, and less expensive, depending on the thickening method you choose.

The thickening process can be as seamless as exposing it to evaporate, but only if you have enough time and patience to wait. Luckily, you can also fasten the process by investing in commercial thickeners like HEC and drywall joint compound.

Knowing when and how to thicken latex paint can take the stress out of your painting projects. It can help you deliver professional-looking pieces to your clients or for your elegant home. 

We hope the steps shared in this article will come in handy in your next painting project!

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