Efflorescence is a deposit of soluble salts, usually white in color, which can appear on the surface of masonry or concrete.
How Is Efflorescence Formed?
Three circumstances must take place for efflorescence to form (without all three, efflorescence can not form). The circumstances are as follows:
- Soluble salts must be present in the concrete or masonry.
- Moisture must be present (moisture can be present in the air, on the surface, or in the concrete) to pick up the soluble salts and transfer them to the surface of the concrete or masonry.
- Evaporation or hydrostatic pressure must cause the solution (salt and water) to move to the surface.
How To Remove Efflorescence
Because efflorescence forms from moisture, and moisture is present from water, if you wash the surface with water the efflorescence will come back once the surface dries. The best way to remove efflorescense is with a stiff brush and acid-based solution.
How To Stop & Prevent Efflorescence
Once the efflorescence has been removed, waterproofing the concrete with a sodium silicate sealer should prevent any further efflorescence problems. The sodium silicate sealer will penetrate deep into the concrete (the Foundation Armor sealer penetrates up to 6 inches), preventing water, salts, and even radon from reaching the surface. Most silicate sealers can be used where hydrostatic pressure is present which is why it is the best sealer to use. Acrylic and epoxy sealers can’t be used where hydrostatic pressure is present so if you intend on using either or those sealers, use a silicate sealer first then apply an acrylic or epoxy sealer on top (it is of course always best to research all products to make sure the combination is okay or to check for special instructions).
What Does Efflorescence Look Like?
A gallery of efflorescence images: