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A Dictionary Definition of “Efflorescence”

1. the state or a period of flowering.

2. an example or result of growth and development: “These works are the efflorescence of his genius.”

3. Chemistry.

a. the act or process of efflorescing.

b. the resulting powdery substance or incrustation.

4. Pathology. a rash or eruption of the skin.

Note that this is a “process”, not the resulting stain.

In construction we tend to use the word “efflorescence” as the definition of the white residue and its chemical component.  Sometimes we jump to the conclusion that any white residue is “that kind of efflorescence”.  It is important to remember that, per the definition above, efflorescence is a process, not a thing.  The typical efflorescence we encounter has the fizzing reaction to acid.  However, the efflorescence process is actually any liquid (almost always water) transporting “any substance “ that can be carried to the surface.  The substance can be a wide range of things, such as iron oxides, concrete additives ( latex, acrylic, epoxy, etc. ).  Many of these substances are white, but some are not.

Therefore, the process of efflorescence could leave a residue of something other that the usual minerals.  This is why it pays to do some testing first.   If there is no fizzing, see the subject of “additives” as it is not uncommon to see that type of residue appear (especially from grout or concrete additives that are “bleeding out”).

This information applies to efflorescence on all surface types,
including brick, block, tile, grout, slate, stone, concrete work, pavers, limestone, marble, granite, etc

Where it comes from! — How to remove it! — How to stop it!

Where does it come from?

Two conditions must be present to create efflorescence:

  1. A source of water soluble salts.
  2. Water moving through the material to carry the salts to the surface. The water evaporates and leaves the white powder behind.

Some surfacing products are more prone to have efflorescence because:

  • They might be more permeable and promote water travel.
  • They might tend to have higher water soluble salts in some batches.

Despite the best efforts of surfacing manufacturers to minimize water soluble salts in their products, they use materials from the earth that can vary from batch to batch.

The causes and treatments of efflorescence are the same, regardless of the material on which it appears. Flooring, roofing, walls and their component materials only vary in the product application technique, as described on product labeling.

Water sources can be:

  • IN/OUT – Entering at the surface (rain or sprinklers), penetrating in a fraction of an inch, then returning to the surface carrying the salts.
  • THROUGH – Entering from behind (bad flashing, caulking, leaks) or underneath (water from the earth migrating up) and traveling through.

There are two kinds of efflorescence.

  1. Regular “powdery” efflorescence as described above and is still gone after “Efflorescence Treatment” dries.
  2. “Crystalline” efflorescence. When powdery efflorescence goes through cycles of being deposited on the surface – re dissolved when new water occurs – drying out – new water – etc. it can form crystals. The crystals become tightly bonded to the surface. The crystals do not have to be thick. A light haze that is still there after using “Efflorescence Treatment” will be light crystal formation and is treated as described below.

How can it be cleaned?

“Powdery” efflorescence only requires a simple application of Vinegar and water with a scrub brush

  • “Efflorescence Treatment” is not a cleaner that must be rinsed or removed.
  • “Efflorescence Treatment” carries the salts below the surface.
  • “Efflorescence Treatment” enhances the surface color.

“Crystalline” efflorescence can not be moved by “Efflorescence Treatment” because of the crystal’s attachment to the surface. That is why you may treat a surface with “Efflorescence Treatment” and it looks great for a few hours. But then, when it dries you can see some efflorescence deposits remaining. They are not new deposits coming out. They were just temporarily disguised by the darkening effect of the initial treatment. The reappearing efflorescence is crystalline and is bonded to the surface. These deposits will “fizz” on contact with a strong acid (pool acid, muriatic acid), but do not use that acid for cleaning. There are products for cleaning.

How it can be stopped!

After treating the surface to restore its appearance, you can prevent future efflorescence by applying a penetrating sealer per directions. This is true even if the water is coming from behind or subsurface and cannot be stopped.  The  penetrating sealers create a barrier below any absorbent surface that allows water vapor to “breathe” out, but stops the water soluble salt molecules from migrating out.


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