Calcite and Efflorescence : What's the Difference?

Calcite and Efflorescence : A Fixable Issue

All of the exterior stonework and mortar around properties is filled with various salts which are deep in the mixtures of the substrates. Learn how these salt deposits lead to the development of calcite and efflorescence, and what can be done to clean them.

When it rains, the water penetrates deep into the stone surfaces and mortar. Once the rain stops and the moisture evaporates, the tiny droplets of water leave behind substances which are too heavy to carry into the atmosphere, such as salts and minerals. The minerals just leave behind easy to remove staining, whereas the salts become efflorescence or calcite.

Efflorescence is the white, powdery substance that can be seen on compromised stonework, whereas calcite is the hard, white/yellow colored substance on or near stonework that is difficult to remove. Both are an indication of an underlying structural issue which is allowing moisture to penetrate into the stone, whether it be failed mortar or poor drainage.

How to Clean Efflorescence and Calcite from Exterior Surfaces

Pressure washing with chemical treatment is the best way to clean and remove efflorescence and calcite. In many cases, chemical treatments are the only way to remove the calcium buildup of calcite.

Efflorescence is fairly straightforward to clean as it can also be removed with just hands. An application of a diluted acid mixture is applied, followed by a pressure wash of the surface. This method of cleaning takes care of efflorescence stains fairly quickly and without damage.

Calcite is much tougher to remove as it contains multiple layers of bonded calcium, which a pressure washer alone can’t touch. The proper way to remove calcite is with hydrochloric acid, or HCL, an acid which has the right properties to break down the bonds between the salts allowing them to be washed away. Multiple applications of high strength HCL are many times the only way to make a difference, as the bonded layers of calcium have taken several years or even decades to build up.

Additionally, calcite acid washing needs to take into account the surrounding areas such as concrete floors, plants, etc. The run off from the acid washing can severely damage and stain floors, and also kill plants both immediately and from the toxic fumes. The correct personal protection equipment, such as gas masks, gloves, glasses, and hats, should be worn at all times to prevent any damage to the person performing the service as well.

What Should be Done to Prevent Further Issues

Acid washing calcite and efflorescence build up is the best way to clean and remove the staining from these issues. Since these deposits are the result of moisture buildup, the structural issues should be fixed first. In many cases, the root cause is damaged or missing mortar, which allows rainwater to slip directly into the stone installation.

This water has no place to evaporate properly, so it just stays there. Since water always finds a way out, it pushes out through the stone carrying salts such as calcium out with it. The small calcium deposits bond together over time to form calcite. Fixing the structural issues such as failed mortar is the first step in resolving this issue.

After the mortar is repaired, it can take 6 months or longer for all the moisture to fully evaporate from the stone work. It is only after this period of drying when the acid washing can be done, because doing it earlier will result in the staining coming back from the leftover moisture.

To book your calcite and efflorescence cleaning, contact Queens Pressure Washing L.L.C. to start the estimation and scheduling process.