A Complete Guide about Efflorescence on Walls

What is Efflorescence?

Efflorescence is a type of white deposit found on masonry and walls. The local names for it are Kallar and Shora. Efflorescence is not a good sign as it means that the quality of construction material may not have been good.

“Efflorescence” is the term most commonly used to describe the deposit of crusty white mineral salts that appear on a masonry surface (concrete, brick or mortar) that have leached out from within the substrate when moisture migrates through it.

How does it occurs?

Efflorescence is a complex problem to understand. Efflorescence occurs when water reacts or mixes with masonry materials to move salts to the surface of the element. In some cases, the water reacts with the masonry components to create free salts and other cases.

Let’s understand it more.

Due to the use of salt water during construction and through rains, the salts (like sulfates or magnesium, sodium andcalcium carbonate) present in the wall get dissolved. On evaporation, the previously absorbed water along with salts appears on walls as crystallized patches or a layer of white powder.

It is formed when water reacts with the natural salts contained within the construction material and mortar. The water dissolves the salts which are then carried out and deposited onto the surface by the natural evaporation that occurs when air comes into contact with the surface of the wall or floor.

It sometimes also occurs due to any source of moisture like due to any leakage in attached or associated areas.

Why efflorescence happens on plaster and painted surface?

Presence of salt in the lime, cement, sand, bricks and sometimes even in water used in construction work are the causes of efflorescence on plaster surface. After completion of plaster work and when it becomes completely dry; soluble salts dissolved by moisture are drawn to the surface through pores. These soluble salts absorbs moisture from atmosphere and on drying, they get deposited in patches in form of white crystalline substance. The surface gets disfigured by ugly damp patches of efflorescence. This defect gradually disintegrates the structure. It is normally of temporary in nature as it disappears during wet weather and reappears during dry weather.

Efflorescence itself is not causing damage to the wall but it will damage any paintwork or wallpaper that you put over interior walls affected by efflorescence. However this build-up of salts on the surface of the wall is a sign that the wall has been wet, so you will need to check what has caused the damp that has led to the efflorescence.

How to prevent efflorescence in new building?

Efflorescence may occur within the first year of a new construction project. Some points to prevent efflorescence in new building:

  • The use of damp proof courses should be made wherever necessary.
  • Only burnt bricks and clean water (free from salts) should be used.
  • The masonry or plastered works should be well protected at night and during rain to exclude extra water.


It should be recognized that there must be water or moisture present to dissolve and/or transport these salts; so the source of the moisture needs to be detected and treated first.

Efflorescence will only stop forming when the migration of moisture through the substrate stops. Unless the source of the water or moisture causing the efflorescence is traced and eliminated (if possible), it is highly likely that the salts will continue to reappear over time. Failure to remove the source of water ingress allows more efflorescence to form, resulting in subsequent damage to the existing painted surface. For detecting the source of moisture, you can hire professional who use advanced thermal imaging technology to detect it.

For efflorescence affected walls, a product of asian paints smart care Damp block 2K1 can be used as per manufacturer’s specification.


Efflorescence is indeed a potential hazard to brick and masonry-based buildings. If efflorescence not treated at the right time, will be leading to various damages like paint deterioration, disintegration of masonry & plaster and damage to associated areas. This will create unhealthy living conditions for residents and add extra cost due to repairs.

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