Correct application of concrete sealer is critical for it to look and perform the way it should. However, whitening, also known as cloudiness or blushing, of sealer is a common problem that can happen some time after application, and many people wonder why it happens.
With water-based concrete sealers, high humidity or low temperatures can cause it to turn white, as well as reapplying before the sealer has completely dried. With solvent-based sealers, application on fresh concrete or applying it too thick can result in a cloudy or white appearance.
There are many reasons that can contribute to whitening of concrete sealer. Read on below to learn more.
Table of Contents
- Why Does Concrete Sealer Turn White
- How to Prevent a Milky White Concrete Sealer Finish
- Frequently Asked Questions
Why Does Concrete Sealer Turn White
Whitening of concrete sealers, or when they become cloudy, are a common occurrence, especially if you use wet-look or glossy acrylic concrete sealers.
Below are the main reasons concrete sealers turn white, and you’ll also learn how to remove and fix them, based on the type of sealer used:
Causes of White Water-based Concrete Sealer
High Humidity or Low Temperatures During Application
Applying concrete sealers with the right environment is critical, especially when working with water-based sealers. The ideal temperatures are between 70-80F and under 50% humidity.
That’s because it dries up through coalescence, a process where the water and the solvent will evaporate, causing the acrylic molecules to fuse together and leave you with the sealer film that protects the surface.
When you apply water-based concrete sealers in too high humidity or low temperatures, coalescing solvents evaporate quicker than the water, causing the sealer to turn white or even powdery since the latex was not fused effectively before it dried. To prevent this, always follow the manufacturer’s directions with regards to the humidity and temperature conditions for application.
This can be corrected by using acetone, though this can only be done if the sealer was applied within a few days. Pour some acetone on a cloth or a brush in order to get rid of moisture that was trapped within the sealer. When this process is finished, scrub off the acetone then reapply the sealer following the manufacturer’s directions.
Another way to fix cloudiness from water-based concrete sealers is by using xylene, which is a stronger chemical compared to acetone. Xylene should only be used if you applied the sealer within the last 48 hours. Simply spray it into the sealer to get rid of moisture. However, if the sealer was applied longer than 48 hours prior, the sealer should be removed and scrubbed off, then reapplied once the xylene has dried.
If your water-based concrete sealer has already completely dried, strip and remove it completely then reapply.
Sealer Was Not Completely Dry Before Reapplying Another Coat
Water-based sealers are easily affected by the temperature and humidity, and if the conditions are not ideal, the surface could form a crust before the water evaporates thoroughly. What ends up is that moisture is trapped, and the sealer turns a cloudy or powdery white.
High humidity and heat can also cause the sealer to dry quicker before the moisture can effectively escape.
To fix this, strip and remove the sealer then reapply.
Causes of White Solvent-based Concrete Sealer
Applying sealer to fresh concrete with bleed water, or a wet surface
When this happens, the sealer is unable to bond with the concrete surface and will end up floating on the water.
Applying sealer too thick
Blushing or cloudiness can occur with concrete sealer over time because the application was too thick. When you apply heavy coats of concrete sealer many times throughout the years, moisture ends up getting trapped under the sealer’s surface, resulting in loss of its adhesion to concrete. Trapped air and moisture underneath will then look white to the human eye, and will gradually flake or peel off.
To correct this, use xylene or acetone anywhere on the white spots or areas. Spraying directly onto the sealer or brushing it on will give you the best results, as this will thoroughly release the trapped moisture. Once the chemicals are removed, the sealer can then be reapplied.
However, if the solvent-based concrete sealer hasn’t dried or cured, a blower can be used to resolve the problem. If none of these solutions work, the only thing left to do is to strip off the sealer and then reapply.
When using xylene, always wear protective equipment such as gloves, respirator masks, and goggles at all times. Xylene is toxic when inhaled or touch, and can cause illness. An alternative to using xylene are specially made concrete sealer strippers, which are also available in the market.
Causes of White Stamped Concrete Sealer
Oftentimes, using a stamped concrete sealer will result in cloudiness because of trapped sand. This can be fixed by completely removing the sealer, then using white vinegar to remove the sand. Once this is finished, carefully reapply the sealer.
Excess moisture can accumulate when using stamped concrete sealer. To remedy this, spray xylene on the surface as this can correct the white or milky appearance.
If none of these methods work for correcting cloudiness in stamped concrete sealer, just reapply carefully.
Causes of White Spots
White spots or patches can also occur after applying concrete sealer. It’s typically caused by the accumulation of excess moisture on the surface prior to application of the sealer, or the incorrect environmental conditions during the drying process.
You can fix white spots by scrubbing a thinner to the affected area, which will reactivate the sealer and hopefully let some moisture escape. This process may have to be repeated several times. If it doesn’t work, you will have to strip the coating and reapply sealer.
How to Prevent a Milky White Concrete Sealer Finish
Here are some general guidelines to remember when applying concrete sealer to avoid this problem:
With these in mind, you can say goodbye to the problem of your concrete sealers turning white.
Frequently Asked Questions
How to use xylene to remove concrete sealer?
The correct way to use xylene to remove concrete sealer depends on the kind of sealer used:
Water-based concrete sealer: Etch the surface using muriatic acid, which will neutralize it. Alternatively, you can mechanically remove it through blasting, sanding, or grinding the surface coating.
Solvent-based concrete sealer: Apply xylene using a brush or spray to get rid of the sealer. A power wash will effectively clean it.
When working with xylene, keep in mind that you must have the proper protective equipment such as respirator masks, gloves, and goggles. This is because xylene is toxic for humans, and you must be careful not to inhale or touch it when working with it.