Did you know that the white, powdery tint on brick and stone has a name?  Yep.  It’s Efflorescence.  This substance is a deposit of salts which form if water is present.  Some people like the look on clay pots for a vintage appearance but on retaining walls and other building surfaces it looks like structures are grimy and not well kept.

What Creates Efflorescence?

This condition can appear both inside and outside.  It will vary in intensity depending on moisture and temperature.  Three conditions are needed for efflorescence to accumulate:

  • There must be water-soluble salt.
  • There needs to be a source of moisture.
  • Material needs to be porous enough to allow salt to seep through to its surface. As the moisture evaporates, the salts will crystallize.

Climate is the major source of moisture but condensation, ground water and activities can also produce moisture generation. Efflorescence is typically a seasonal concern with humidity being highly impactful in determining when salts will appear.

Identifying Efflorescence

It is important to understand the difference between efflorescence and staining.  Stains can come in a variety of colors. Efflorescence will be greyish white and present as a powdery substance.  It will appear on unsealed surfaces like brick, cement and clay.

Removing Efflorescence

Pressurized water will help to dissolve efflorescence, but you will need to dry off the surface completely after the wash.  If moisture remains the efflorescence is likely to return.

Household vinegar is effective in eradicating the build-up.  Simply dilute some white vinegar and apply to the surface with a sponge or a spray bottle. Allow to sit on the surface for a few minutes and then wipe dry.  This is less harmful solution than using harsh chemicals and more than likely to already be in your kitchen cabinet.

Scrubbing with a strong brush should easily eliminate the efflorescence. For a double punch, wipe with vinegar solution after the scrub down.

Whatever method you use, it is important to tackle this chore in warm, dry weather.

Preventing Further Build-Up

There are water repellents like silicone and acrylic coatings that can help prevent future building up of efflorescence. Check with a landscape professional to recommend a good product for North Texas. The coating will repel moisture across the porous surface.  To apply a coating properly, try this process:

  1. Rinse the surface with water hose or if indoors you can use a spray bottle. Wipe off the excess moisture.
  2. Apply the repellent according to package directions and allow to sit for a few minutes. Check instructions to see if you need to apply a second coat.
  3. Rinse surface again with water then use a clean, dry rag to remove all moisture.

The sealed surface should eliminate or greatly reduce future build-up of efflorescence.

Bottom Line

These salt deposits are just an aesthetic problem. They do not compromise the structural integrity of any retaining wall, pavers or other porous surface.  You should consider though that any chronic water that is seeping into the masonry surface can cause problems over time. If you have concerns, consult with a landscape professional.