Why Is My Stained Concrete Turning White?

The Ugly Truth: How Moisture Can Ruin Your Decorative Concrete

Not only does excess moisture evaporate; it takes with it the design. With proper moisture checking, you can preserve the template and concrete before adding stains and sealers.

In decorative concrete, beauty and strength converge. They fuse together like a good acid stain to create a long-lasting, pleasing floor that practically becomes the base of its space and atmosphere. To achieve the desired result, you need to weigh a number of variables for the particular combination of stain and sealer you pick.

The moisture content in the concrete at the time the stain and sealer are applied is one of the most important variables that need your attention. There may be two main sources of moisture in the concrete. The first is the quantity of water used to mix concrete with cement. Second, external water sources can be a concern, such as water that, in the absence of a vapor retarder, can move from the ground to the concrete slab.

Both evaporating water and pooled water can interfere with a stain or sealer.

Signs That the Finish Was Applied at the Wrong Time

The damage that excess moisture can do to your stain or sealer can look different depending on the amount of excess moisture and the type of stain or sealer used. 

Why is my concrete turning white?

Efflorescence – As the concrete dries and its moisture rises upwards through the slab, it brings salts within the concrete to the surface as well. This leaves a white sticky residue called “efflorescence” when too much moisture passes through the concrete. As beautiful as the word sounds, efflorescence is rather unsightly.

Depending on whether the floor has been finished or not, there are different ways in which the efflorescence occurs. Upon staining, but before binding, it can leave a white powdery substance on the surface of the concrete. If the efflorescence is trapped under a sealer and/or some stains, a white “blush” will appear on the concrete.

Efflorescence can cause other stain or sealer failures, which are noted below.

Stains: Reactive and Non-Reactive

The concrete is colored in different ways by reactive and non-reactive stains, resulting in different indications of moisture damage. In the case of reactive stains, color variations are usually associated with the problems.

Undesirable color changes – The acid in reactive stains contains metal salts that, when combined with the free lime in the concrete, cause a chemical reaction. This reaction provides the color of the dye, but the salts or acids in some blue and green stains can turn brown or black when there is excess moisture. The exact cause is not obvious, but the most common theories refer either to oxidation or a fungus the unwelcome color change, both of which can occur with excess moisture.

Lighter or uneven coloring – Efflorescing salts in the presence of excess moisture will retard stain penetration, which interferes with the chemical process of the acid stain coloring the concrete.

In the case of excess moisture, the use of non-reactive stains contributes to a different set of problems. Because a non-reactive stain, stains the concrete by filling the pores of the concrete or by forming a film that lies on the surface of the concrete, common problems associated with moisture include flaking, peeling, bubbling, blistering and dark spots.

Flaking and peeling – an indication that the stain failed to bond with the concrete due to excessive moisture

Bubbling or blistering – caused by moisture that can’t escape

Dark spots – a sign of trapped moisture that can’t evaporate