How To Thin Latex Paint By Using Water And Commercial Thinner

Dealing with latex paint can often be a daunting task to most people. This is often because many painters don’t really understand what latex paints are and the general specifics on what to do and not to do. While this is understandable, there’s a little bit of science behind successful paint jobs.

Most beginner painters often struggle with the question of how to thin latex paint ;

  • How much paint goes on every square meter of surface?
  • What is the right paint to thinner ratios and most importantly?


These are some of the concerns I aim to address in this article and hopefully demystify the whole process. I have made the thinning processes as simple and concise to follow as I possibly could with both water and commercial thinners. Pay keen attention to the volumes and thinner ratios.

As with mineral oil based, latex paints require proper thinning if the goal is to achieve a perfectly coated surface. Other factors such as the type of the surface (wood, metal, concrete or others) and the paint application technique also come into play. Before delving into the thinning process, it is appropriate to understand what a latex paint is. Latex is a naturally occurring substance found in plant stems of the rubber tree originally of Brazilian descent. The kicker however is, there is no actual latex in latex paints! Instead, synthetic polymers that mimic the appearance of natural latex but with an entirely different chemical composition from the base of the paint.

This property of latex paint is especially useful to people who experience natural latex allergies and associated medical conditions.

Things You Will Need

Before proceeding with the thinning process, it is important to note that not all latex paints require thinning. A simple test can easily determine whether or not thinning is necessary. You’ll need the following implements;

  • A stirring rod. This will particularly come in handy while ascertaining whether or not a latex paint needs thinning.
  • Two empty containers of reasonable volume. Two 10 liter containers would suffice.
  • Commercial thinner or at least 5 liters of water. Similar results will be observed with use of either. The difference comes in with post-use storage of the thinned paint. Latex paint that has been thinned using commercial thinners has a shorter shelf life compared to paint thinned using water. Commercial thinners are also pricier to acquire.
  • 4 liters of Latex paint in your desired color.
  • A calibrated liquid measuring container such as a jug.
  • A source of water.
  • A bunch of used newspapers.

The Working Surface

thinning paint prepairing space

First, place the used newspapers on a flat surface such as a floor or a large table. This will form the working surface where spills will be easily cleaned. Arrange the newspapers to form a square approximately one meter squared.

Thinning work Test

This step is important to carry out before commencing the thinning process. Open a latex paint can and place the stirring rod in the paint. Leave the rod in for about two minutes and slowly lift it up above the paint surface in the can. Observe the texture of the paint as it drips from the stirring rod. If it appears smooth and flows well, the paint doesn’t need thinning. If the paint appears to flow thicker than usual or contains thick lumps or coagulates of paint, then proceed with the thinning process.

Method 1: Mixing Ratios (Using Water)

Having established the need for thinning, it is important to carry out this step with precision. I’ve had to dispose of paint previously due to incorrect paint to thinner ratio rendering the paint unusable.

1. In one empty container, pour in half of the paint (2 liters).

2. Using the calibrated jug, measure up a volume of water equal to 200 milliliters (200 ml) and add to the two liters of latex paint. Repeat the process with the other empty 10-liter container.

3. At this point, use the stirring rod to mix the paint and water into a smooth mixture.

4. Measure up another 200ml into each of the 10-liter containers and once more mix well. Another method to get this mixing process done would be to pour in the paint and water mixture back and forth from one 10 liter container to the other. Be careful while using this technique, spills aren’t uncommon with beginners.

  • The end result is a well thinned smooth latex paint that is ready to go onto the desired surface. Be careful not to measure up large amounts of water into the paint at a go. More often than not you’ll find that you have painted of a light undesired consistency. The perfect consistency for thinned latex paint is considered by most paint experts to be light for interior paint jobs and a thicker consistency for outdoor surfaces.

Method 2: Mixing Ratios (Using Commercial Thinner)

If you decide to go with commercial thinners, the process is similar, and the thinning additive is often measured out for you and accompanied with instructions. As mentioned earlier, commercial thinners are considerably pricier compared to water so consider using water as a thinner first.


Having settled on using commercial thinner over water, it is important as well to get the thinning process correct. Use similar implements as the ones used in the case of water as a thinner. The process is as follows;

1. In the two clean and empty 10 liter containers, measure out a starting volume of 200ml commercial thinner.

2. To each container holding 200ml of commercial thinner, pour out 2 liters of latex paint. Using a clean stirring rod, mix the latex paint well with the thinner.

3. After observing the thinner has mixed with the paint to form a uniform paint solution, measure out an additional 200ml into each container holding approximately 2.2 liters of paint and commercial thinner solution. The final volume in each container should now be 2.4 liters.

4. Once more use the stirring implement to mix the paint and the thinner well. To ensure a uniform mix, pour the contents of one 10 liter container into the next back and forth repeatedly.

5. The net result should be a smooth uniform paint mixture that is ready for application onto a clean surface of choice. The idea here is to ensure that the final product isn’t too light or too thick for application. I recommend sticking to the specific volumes I’ve described above.

  • An important note to observe while using commercial paint thinners is, ensure you are in a well-ventilated room and observe the use of a face mask while carrying out the entire thinning process.

See more how to thin latex paint for airless sprayer in this video of EarlexMR


Understanding all the above has so far helped me appreciate all the hard work that goes into a perfectly painted surface knowing well all the science and art behind it all. The items I included in my list was important to me because the chances that errors in the mixing of the thinner and paint were minimal every time I needed to paint. Furthermore, spills, stains and nasty patches of paint are harder to come by.

I’d recommend adherence to the itemized list for best results. It is my sincere hope that my tutorial was as fun as it was enlightening. Please share your thoughts on the article in the comments section and share with your friends. All the best!

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Jose A. Brown

Jose A. Brown is a mechanic engineer and an enthusiastic blogger whose mission is to provide the readers with the best tips, guides in the Home Improvement, DIY Project, and Industry.

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