Published Monday 19th of May 2014 // Updated Monday 30th of January 2017
Problem: Concrete Sealer Blushing
Fix: Concrete Sealer Blushing also known as whitening is a common problems when applying a decorative solvent based acrylic sealer. Blushing usually occurs when a sealer is applied to a concrete surface that is wet or newly poured. The sealer is unable to adhere to the concrete surface and instead will bond with the layer of water. Blushing also occurs when the sealer is applied too heavily or thick or when there is a lot of previous sealer buildup. This build up of sealer will trap moisture under each layer and over time all of the sealer layers will delaminate from the concrete. In order to avoid this make sure the concrete substrate is complete dry before application and apply the sealer in thin, even coats instead of one heavy coat.
Problem: Concrete Sealer Staining
Fix: Since acrylic sealers do not provide exceptional stain and chemical resistance it is common for leaves and oils to stain the sealer after application. Try a different type of sealer such as a silane/siloxane to combat staining.
Problem: Water Based Sealer Turns White
Fix: When applying a water based sealer it is important to note that it dries differently than a solvent based sealer. During application if there is too much or too little humidity this can affect the appearance of the sealer. If the polymers of the sealer evaporate before the water, the sealed surface will turn a powdery white since the particles did not have ample time to come together before drying. In order to prevent this from happening try to seal with relative humidity below 85% a have a substrate that is 5 degrees above the dew point.
Problem: Solvent Based Sealer Turn White
Fix: When a solvent based sealer turns white it is known as blushing. There are two primary causes of blushing. The first of which occurs when applying a solvent based sealer to a substrate that is wet or green and can result in the sealers inability to bond to the concrete. Instead the sealer will be stuck on a film of water. The second which occurs when a solvent based sealer is over applied or when consecutive layers of sealer are frequently applied and never removed. The thick coats of sealer can cause moisture to be trapped under the sealer leading to delamination. In order to prevent this from happening apply sealer in thin, even coats instead of one heavy application.
Fix: When bubbles occur after sealing this is usually a result of over application. It is best to apply in two thin coats even if only one coat is required; two thin coats are much better than one, thick, heavy coat. The first coat acts like a primer and will not look very desirable after sealing. The second coat will add the even, glossy, color enhancing finish.