Understanding Efflorescence

A guide to dealing with one of the industry’s most difficult problems.

Clean-up Efflorescence: Clean-up efflorescence is caused by chlorine ions left on the masonry surface by unbuffered acids used in the cleaning process. As these ions react with moisture, a calcium chloride substance rises to the surface and efflorescence is created.

Calcite: Calcite occurs when a source of excess moisture exists in a masonry substrate. This moisture exits the wall through evaporation or migration through hairline cracks. As the water evaporates from the surface, it leaves behind heavier calcium molecules. This calcium-based residue is sometimes referred to as lime run. Sources of excess moisture include heavy rains that soak brick or block during construction, water migration through hairline cracks or leaks that are left unrepaired for extended periods of time. As the water evaporates from the surface, it leaves behind heavier calcium molecules.

Weather efflorescence: This occurs in the winter on the outside of walls where the interior has a lot of water vapor, such as swimming pools or institutional dish rooms, and the exterior has exceedingly dry air. This dries and disappears as soon as humidity is restored and is not worth cleaning.

White Scum: White scum really isn’t efflorescence since it is insoluble to water and most acid-based cleaning solutions. It’s also very difficult to diagnose since it looks very much like efflorescence and calcite. White scum is caused by masonry detergents reacting with minerals within the brick. This results in an insoluble salt formation.

Efflorescence on Pavers

Block pavers and retaining walls are becoming increasingly more popular landscape choices among homeowners and businesses alike. Pavers can add a rich and elegant look to retaining walls, driveways, walkways and patios. Yet, much like traditional brick and block products, pavers are susceptible to efflorescence as the photos show. On pavers, Pav-R Clean is excellent at removing light efflorescence. For block walls, Pav-R Clean is equally effective on light efflorescence although heavier deposits may require NMD 80 or EF-Fortless as well.

This retaining wall efflorescence was removed with two applications of calcite remover that was misted on with a trigger sprayer and two or more applications of 4:1 NMD 80 followed by a rinse. Powdered efflorescence may be removed with a single application of NMD 80 or EF-Fortless.

The photos above depict a worst case scenario for pavers (left side) since they were taken from a “rejection” pile at a block company in western Pennsylvania. These pavers were treated with Pav-R Clean which effectively restored their rich color. If heavy calcite is a problem, follow Pav-R Clean with an application of Calcite Presoak followed by NMD 80.

Treating Efflorescence With EaCo Chem Products

Due to the variety of types and causes of efflorescence, EaCo Chem feels that testing is critical to solving any efflorescence problem. In addition to finding the right product to remove the efflorescence, care and consideration must be given to the type of masonry surface that the efflorescence has affected. For example, the product or dilution rate used to remove calcite from buff brick will likely be different than that used to remove it from synthetic block. That’s why EaCo Chem backs its products with technical support. Through a combination of our website, sales represenatives and telephone support, we can usually assist you in finding the right solution to your problem.

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