Condensation & Paint Blooming Issue Solver

During the winter months, Promain are often asked why is my garage or workshop floor paint blooming. If you are not sure what paint blooming is, read this article to find out more.

What Is Condensation?

You might be asking why is there condensation on my floor. But what exactly is condensation?

Condensation is water that collects as droplets on a cold surface when humid air is in contact with it.

Condensation can happen on any surface. Therefore, condensation on a floor is just the same as condensation on a glass window. Concrete floors are often constructed from concrete that is approximately 800mm thick. Because of their thickness, they can take many weeks to warm up.

We always recommend the summer months as the best time to paint floors. This is as the concrete floor slab will be warmer. This will prevent condensation forming on the floor. Also, the paint will dry quicker if the floor slab is warmer. Ideally you want to avoid any condensation floor slab issues.


What Is Paint Blooming?

Paint blooms when moisture penetrates the paint surface creating a milky effect.

Paint blooming on floors is when moisture or condensation forms on a floor that effects the paint. Paint blooming  creates a milky appearance. An example of the effect of paint blooms on a concrete floor is below:

Paint Chemistry Effects On Blooming

If you apply a floor coating and the paint is not fully cured, paint blooming may not always be a problem. The type of paint used depends if blooming is a problem or not.

For example, acrylic paints are more susceptible to blooming than say a two pack epoxy or polyurethane. When acrylic floor paint has been allowed to dry, this blooming will often disappear over a period of time. Acrylic floor paints can look a different shade or colour when wet as opposed to dry.  Therefore, you may notice patches or blooms when condensation or dampness occurs at any time. This is more apparent on large floors like warehouse floors or in garages that suffer from cold.

Types of Paint Blooming

Paint blooming doesn’t just happen on floors. Paint blooming defect issues can occur on various substrates.

Pool paint blooming can happen if swimming pool walls and floors have not been allowed to dry fully before the application of any paints.

Spray paint blooming is a common fault when applying paint to cars. Traditional car paints such as celluloses can suffer from cellulose paint blooming. A milky white haze or mist can form on the surface of the paint film. This is obviously not ideal! We recommend discussing issues with paint blooming on a car with a specialist applicator.

Best Paint Types To Prevent Blooming

Painting on a wet surface can cause paint blooms. This is because the dampness in the substrate needs to escape and as this moisture migrates through the paint it will create a blooming effect. Microporous paints however, will allow this moisture to transmit through the coating more easily. The most microporous paint for walls is limewash. Classidur is also an exceptionally high performance paint for internal walls. It is often specified for use on historic buildings such as churches. Many masonry paints offer very little in the way of water breathability. This is to stop water getting into substrates such as brick or render. If you require a breathable coating, then we would suggest masonry paints such as Mapei Silancolor.

Can I Paint A Floor That Has Bloomed?

If you have blooming on your floor it can be over painted to cover the blooming. However, you will need to use a microporous paint that allows water vapour to pass through the coating. A good microporous floor paint is a water based epoxy, such as Remmers Epoxy BS 3000 SG New.

How To Stop Paint Blooming Before It Happens

How do you stop condensation on a concrete floor? Following this guidance will help!

If you are able to insulate under your concrete floor, this will keep the floor slab warmer. Therefore, the moisture will not condense on it.

If you are asking how to stop garage floor condensation, remember – paint likes to dry slowly. If a paint dries within the temperatures recommended on the products data sheet you will get the best adhesion. This is of course if you have prepared the substrate as the paint product recommends.

Always remember that the floor slab is going to be a few degrees colder than the current air temperature. Each paint product will have stated drying times at certain temperatures. When looking at the data sheet for the drying time of paint, it typically is quoted at an air temperature of 20°C. The lower the air and surface temperature, the longer the paint coating will take to dry. For example, many epoxy paints stop drying (curing) if the temperature drops below 5°C.

How To Stop Floor Condensation

If you are looking at how to fix floor condensation, look no further. If you are asking yourself how do you stop condensation on a concrete floor, follow the below instructions.

The use of a dehumidifier will reduce the amount of water in the air therefore this will reduce cold floor condensation.

We also advise to look at the weather forecast for the following 24 hours before you paint a floor, even if it is indoors. If you must apply your floor paint during colder months, a good way of reducing condensation on a floor is to heat the room with electric heaters. This is before the application of paints to bring the floor up to a suitable temperature. However, do not use a gas heater. Typically, bottled gas heaters (Calor etc.) produce about 8 pints of moisture from an average-sized gas bottle.

It could easily take a couple of days to increase the temperature of a concrete slab even with additional heating. Be warned if you are in a rush! This will help with how to stop paint blooming and how to stop condensation.


Below we have listed a few FAQ’s on concrete floor condensation, cement floor condensation and epoxy floor condensation issues. Let us know if there are more how to fix paint blooming questions you would like us to add:

Why is there condensation on my floor?

If the floor slab is cold and the air is warm, water will condense on the floor slab. This is similiar to condensation on windows in a house.

How to get rid of condensation in a room

If you have a floor with condensation, you need to increase the temperature in the room to help the floor dry. The use of a dehumidifier will help greatly in removing the moisture in the air. Ventilation is a good way to reduce concrete floor condensation.


Are you still struggling with 2 pack paint blooming or how to stop condensation on floors? For individual guidance on how do you stop condensation on a concrete floor contact us today. Our technical team have a huge range of knowledge to help customers no matter the issue. Contact us on 01462 421333 or via our contact page.

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