Can You Water Down Masonry Paint?

by Sam Wood | Last Updated: 16/05/2021

There are lots of different reasons why you may want to water down your masonry paint before applying it, but is it possible? And, should you? We have got some masonry paint and tested watering it down ourselves so read on for the results.

Testing if you can water down masonry paint

So this test is nice and simple. I grabbed some masonry paint and brick. Watered down some masonry paint and tested it against its unchanged brother to see how it fared.

watered down masonry paint on brick

watered down masonry paint on brick

On the left is the regular masonry paint and on the right is the watered-down version. Both versions are well and truly stuck to the brick so they both worked. As you could guess beforehand and can definitely see in the pictures the watered-down paint will take multiple coats to reach the same level of coverage as the regular masonry paint.

Further testing

This brick will now be left outside exposed to the elements to see how the watered down masonry paint performs when compared to regular masonry paint, so check back for progress updates!

Water-based vs oil-based

Please note that watering down masonry paint will only work if the paint you have is water-based. Most masonry paints are water-based but there are a few oil-based versions available so be careful.

If you want to water down an oil-based paint this is called thinning and you will need to use paint thinners or white spirit in place of water.

How to water down masonry paint

The easiest way is to move some of your paint into a bucket or paint kettle. You then want to add some water and mix thoroughly. A 70:30 mix (70 parts paint to 30 parts water) is a good mixture to aim for although this is up to you.

I recommend not mixing in the tin in case you want to use the unwatered down version later.

Why would you want to?

There are numerous reasons you may want to water down masonry paint, I will list some of the more common reasons below.

Mist Coat/Seal Coat

This is a common decorators trick to make your paint go further. On porous surfaces, which masonry is, the first coat of paint is often soaked up and doesn’t cover well. To reduce paint loss here decorators use a trick called a “mist coat”.

A mist coat is a watered-down coat of paint applied first and then painted over with regular coats of paint once dry. The mist coat seals the surface you are painting while using less paint. Now that the surface is sealed the following coats will not soak in as much, potentially saving you a lot of paint.

To Spray

This is probably the most common reason for adding water to masonry paint after a mist coat. If you are spraying your paint onto your walls then it is common practice to water it down first.

Paint sprayers require the paint to be very thin to work correctly so it often needs to be watered down.

This of course means that you have to use more coats when spraying, this is more than made up for though with the time saved when compared to regular painting.

Whitewashed look

Some people just prefer the whitewashed look that watered-down masonry paint can provide. If this is the aesthetic you are going for then you obviously will want to water down your paint before application.

Learn More About Masonry Paint

This article is part of our masonry paint section, learn more about masonry paint with the following articles:

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Wood by name, wood by nature. I am a fully qualified, time-served, award-winning joiner with an NVQ Level 3 in Carpentry and Joinery as well as an HNC in Construction. Beyond my joinery qualifications, I have also earned a degree in building surveying. I believe these qualifications make me perfectly positioned to provide expert advice on many different areas of DIY as well as share all of the tips I have picked up in over a decade working on building sites!