Understanding Efflorescence


What is Efflorescence?

First, let’s define the difference between efflorescence and calcium deposits. Efflorescence is a deposit of salt that collects on the outside of a concrete or masonry surface. Calcium deposits (also referred to as lime buildup) accumulate right below a material’s surface. Both conditions occur when evaporating water pushes minerals in the masonry towards the surface and can be indicators of water damage. 

What Does Efflorescence Look Like?

Efflorescence, a porous substance, looks white and chalky. Since it rests on the surface of the masonry, efflorescence will darken when splashed with water. Calcium deposits are denser than efflorescence and usually appear as white streaks running down a material’s surface. Because the calcium forms right below a material’s surface, water will not affect its appearance.

What is the Best Method to Remove Efflorescence?

If you’ve been searching the internet for a solution to cleaning efflorescence, chances are you’ve come across a solution for trying a 50/50 mix of white vinegar and water and using a bristle brush to scrub the affected surface. While this may work for very mild cases of efflorescence, vinegar and water is not strong enough for severe cases of efflorescence.  Scrubbing the affected area can take hours of hard work, and using the wrong brush can permanently damage the surface, making it look worse than before!

Step 1: How to Properly Clean Efflorescence

A safe, effective, and easy solution to remove efflorescence and most other mineral deposit stains is to use RainguardPro Restore-N-Prep. Simply spray the solution onto the surface and then wait 5-8 minutes (no scrubbing required!). Then rinse off with a power washer or a hose, depending on the substrate. Let it fully dry for 24 hours, and that’s it!

Often efflorescence and calcium deposits can be removed without compromising the structure of the material. However, if there is excessive mineral loss the material can become brittle so make sure to replace this surface if this occurs.

Step 2: How to Prevent Efflorescence From Coming Back

There are two ways to help ensure that the efflorescence and calcium deposits do not come back. These deposits can travel through the masonry when water travels through the surface by infiltrating it  in one of two ways.

Method 1: If the side of the surface that is receiving the moisture can’t be sealed, seal the surface with one coat of RainguardPro Efflorescence Blocker. It works on above and below grade projects to block minerals and alkali from coming up to the surface. Efflorescence Blocker is great for surfaces where waterproofing membranes have failed or have one side touching soil. 

Method 2: The second way to prevent efflorescence is to apply two coats of a penetrating Silane / Siloxane water repellent such as RainguardPro’s Micro-Seal®. This is the best solution for surfaces where ALL sides of the surface can be sealed.


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