Efflorescence
What is efflorescence?
Efflorescence is the process by which salt migrates to the surface of a porous material where it forms a coating (also called Calcium Carbonate or limestone) The appearance of efflorescence is often described as a white, fluffy or powdery substance, but it can range in color from white to gray, brown, or even yellowish hues, depending on the type of salts present. Found on walls and other brick, stone or concrete surfaces, it occurs when evaporating water leaves behind salt deposits on the masonry. There are many installation problems which may lead to efflorescence:
- Using masonry products that are not fit for purpose or of poor quality, these salts can easily migrate to the surface
- Improper ground storage of façade material
- Use of masonry without sufficient ventilation
- Use of masonry in areas that lack a proper moisture barrier
- Joint material failure
- Improper construction techniques
- Environmental factors and climatic conditions, such as high humidity, heavy rainfall, or frequent freeze-thaw cycles.
How to prevent efflorescence
While it is difficult to completely prevent efflorescence, good site practice will help to minimize the occurrence.
- Properly cure concrete after it has been poured, this will help prevent the formation of efflorescence
- Bricks should not be placed directly on the ground
- Mortar should be protected from damp contamination
- Mortar that is not cleaned may lead to efflorescence
- Newly built brickwork should be protected from the elements in the first week
How to remove efflorescence
Efflorescence is temporary. In most cases it will disappear in a few wet winter months in this country, therefore the best solution is often to let it wash out naturally.
- When treating an outdoor wall, make sure the temperatures will be above freezing all day
- Simple washing can sometimes remove efflorescence
- Scrub the affected area with a wet sponge or brush and plain water. Always be sure to rinse thoroughly, if you leave dissolved salts on the surface, they’ll return as new efflorescence.
- Watch out for clay. Clay naturally has a high salt content, therefore removing efflorescence in this way is often only a temporary solution – wet weather can bring salt back to the surface again.
- Using a stiff scrubbing brush, most of it will easily come off
If efflorescence is causing you problems, contact us for expert advice.
