Efflorescence is a crystalline deposit of excess salts that travel with moisture to the surface of concrete. It is whitish in appearance and is naturally occurring in all concrete. Water must be present to carry and move the salts to the surface, once the water evaporates a white hazy substance is left on the surface; this is efflorescence. The denser the concrete, the more difficult it is for salts to travel through the concrete. By sealing with a penetrating concrete sealer, concrete is hardened up to 45% and efflorescence is eliminated. Since humidity can affect efflorescence, it has been shown that it can be a seasonal problem with efflorescence being most common during rainy seasons. Common causes of efflorescence include the movement of groundwater; since hydrostatic pressure can force water and salts to move to the surface. Bricks are also common surfaces that have problems with efflorescence and the combination of a brick and a certain type of mortar may result in increased salt deposits.

Picture this: you have just moved into a new house, your dream home with all the space, yard, and garage space you could hope for. You have this beautiful half-finished basement, of which the other half is exposed concrete: stark and plain, but clean. You spend a couple months organizing and unpacking, and everything is going well, you're really starting to feel at home. One day, however, as you venture into the unfinished part of the basement to find that old screwdriver you know you didnt forget in the move, you are confronted with this white gunk marring your grey concrete walls.

This buildup is nothing more than efflorescence, an annoying and ugly yet ultimately harmless affliction that plagues concrete and brick materials. The phenomenon itself is due to water leaking to the surface of the concrete or brick material, carrying salts that are otherwise locked beneath the surface. The water travels through various pathways within the concrete, bringing along salts that it deposits on the surface before evaporating. After the water evaporates, it leaves behind the salts, which harden into the white gunk that you are currently faced with.

There are three necessary conditions for efflorescence to occur: there must be salts and other chemical additives within the actual material, there must be water leakage into the concrete to bring out the salts, and there must be pathways for the water/salt mixture to travel to the surface. These three conditions are almost impossible to prevent entirely, as you cannot know, for instance, if there are any salts and/or chemical additives within your concrete.

And while efflorescence is harmless, being more of an aesthetic matter rather than posing any structural danger, it is an indicator of an even bigger issue: water leakage within your concrete, a problem that can lead to other, more serious issues such as mold, mildew, and general deterioration of the material.

How to Remove Efflorescence

Efflorescence must be removed before applying a penetrating sealer. In order to remove efflorescene use the Hydro-Etch 1000, a powerful, acid-based cleaner, specifically formulated to clean, brighten and etch concrete in addition to removing efflorescence and excess concrete residue, washing away the built-up salts to leave your walls unmarked.

Please note Hydro-Etch 1000 must be diluted before use. Read all label instructions before application and wear the proper safety gear when applying. After etching, the concrete needs to be rinsed with water and neutralized with baking soda or household ammonia.

How to Prevent Efflorescence

Even if you successfully clean away the efflorescence, it is important to deal with the underlying issue; if you do not seal up your wall with an effective concrete sealer, the salts will simply build up again in the future, necessitating further cleaning and eventually threatening to deteriorate your concrete, leaving your home susceptible to mold, mildew, and other such issues.

The best course of action, of course, is trying to prevent efflorescence before it manifests itself all over your walls. As you cannot control the chemical additives in the building materials, the most effective method of prevention is by closing up the pathways and sealing out the water that would otherwise bring those salts to the surface.

To do this, it is recommended that you treat your concrete walls with a breathable, penetrating concrete sealer like the Siloxa-Tek 8500. The Siloxa-Tek 8500 is able to prevent efflorescence from coming to the surface by reducing moisture intrusion and water infiltration.

8500 Concrete Sealer Bottle

Siloxa-Tek 8500

Water & Salt Repel

1000 Concrete Sealer Bottle

Hydro-Etch 1000

Acid-Based Clean & Etch

Published Wednesday 13th of July 2022 // Updated Monday 7th of June 2021

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