As a manufacturer of terracotta bricks for use in elevation bricks walls or normally called as ‘non-plastered brick walls’ in India, quite a few of my clients have called after the civil installation of bricks that the bricks have developed a whitish or blackish coating.
This powdery deposit or blackening of the brick is called Efflorescence. Not to be surprised, we do have a technical word for this issue. And this is not a local issue with our bricks or the bricks made in India, this is a universal scenario.
So, your immediate compliant that there is a problem with the bricks that we have supplied. For all of you who have raised this issue with us or should you be facing this issue with bricks you have procured elsewhere, we hereby summarize the cause, prevention and removal of this coatings once and for all.
Understanding Efflorescence in Masonry: Causes, Prevention and Removal
Efflorescence is a common issue in masonry, particularly in clay bricks and concrete blocks used in elevation walls.
It manifests as white, powdery deposits and in some places where black sand is used (crushed blue metal) as a blackening on the surface of bricks, often forming after a few weeks or months after construction. Kindly do note that this is not structurally harmful, efflorescence can affect aesthetics and signal moisture-related problems within the structure.
What Causes Efflorescence?
Efflorescence forms when soluble salts within the masonry dissolve in water and migrate to the surface. When the water evaporates, it leaves behind crystallized salt deposits. For efflorescence to occur, three conditions must be present:
1. Soluble salts must be present in the masonry materials (bricks, mortar, cement). Now a days, most experience kiln operators ensure that there are no efflorescence salts in the clay they procure. So, most of the time it is in the mortar and the cement that the workman uses.
2. Sufficient moisture must be available to dissolve and transport the salts. In India, there is a practice to cure the wall no matter what and also the use of copious water for curing,
3. A pathway must exist for the salts to migrate to the surface.
If any one and all of these conditions is eliminated, efflorescence cannot occur—which forms the basis of its prevention.
Preventing Efflorescence in Brick Walls
To minimize the chances of efflorescence affecting elevation brick walls, follow these preventive measures:
1. Choose Low-Salt Materials
– Select low-alkali Portland cement to reduce sulfate content in masonry.
We suggest the usage of premixed mortars. One due to the addictive used for quicker drying with good strength and also as they do not require curing
– Use bricks after requesting for a test certificate from the manufacturer that there is no efflorescence for the bricks
– Ensure clean, washed sand is used in mortar to prevent contamination.
2. Control Moisture Exposure
– Install proper drainage to prevent water accumulation around brick walls.
– Apply waterproof coatings to minimize moisture absorption. We highly recommend this as this also contains the growth of algae on the surface in areas where it rains much or with high air moisture
– Store bricks and cement above ground to prevent exposure to ground moisture.
– Use ventilation to reduce humidity levels inside structures.
3. Optimize Construction Practices
– Tool mortar joints (concave or “V” shapes) to reduce water penetration.
– Use mechanical vibration in grout to remove air pockets and improve density.
– Install flashing and weep holes to prevent trapped moisture buildup.
How to Remove Efflorescence
Despite preventive measures, efflorescence may still occur due to environmental factors. If white deposits appear on brick walls, consider these removal techniques:
1. Dry Brushing
– Use a stiff brush to remove loose powder deposits without spreading salt deeper into the masonry.
2. Water Rinse & Mild Detergents
– Lightly spray affected areas and scrub with mild soap to dissolve surface salts.
– Avoid excessive water, as this might lead to recurrence.
3. Vinegar or Diluted Acid Cleaning
– A mild vinegar solution can help dissolve stubborn salt deposits.
– For extensive buildup, muriatic acid (diluted 1:12 with water) may be used, but must be followed by thorough rinsing.
4. Chemical Sealants
– After removal, apply breathable sealants to prevent further moisture absorption.
– Avoid impermeable coatings, which can trap salts beneath the surface, leading to crypto-efflorescence, a condition where salt buildup causes brick deterioration.
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And so, to summarize, while efflorescence is not a structural issue, it signals moisture management problems.
By selecting low-alkali materials, implementing proper drainage and waterproofing, and using effective construction methods, you can minimize its occurrence.
If efflorescence appears, prompt removal and preventive sealing can help maintain the longevity and aesthetics of elevation brick walls.