Efflorescence can emerge on clinker façades. What can be done to prevent this problem? Which mortar should be used? What are the causes of efflorescence formation on the clinker, and how to remove it?
What is the origin of efflorescence on the clinker?
Efflorescence is formed by the dissolution of salts contained in the clinker / external façade layer or in the mortar. When exposed to moisture, these salts are washed out onto the wall surface, where they dry out, resulting in a white deposit being formed on the wall. It is a normal phenomenon which does not impair the quality or durability of the wall, yet it spoils the aesthetic appearance of a clinker façade.
How to prevent efflorescence on external façades?
As efflorescence only forms when water is found inside the wall, the basic remedy is the protection of the clinker against moisture. It needs to be considered at each stage of the works. When storing the materials, they should be covered with construction sheeting and positioned in such a way that water cannot penetrate into it, even from the ground.
Once the masonry works have begun, it should be remembered to carry them out only on warm and dry days, and to cover the finished sections against rain. For a three-layer wall, both adequate air circulation and an opportunity to ventilate the inside of the wall must be ensured, as this will help the moisture to evaporate freely outside the wall. Emphasis must also be placed on the high quality of workmanship for all joints and flashings.
What is also important is the choice of appropriate mortar which should be specifically designed for the clinker or face bricks, and contain no lime. When mixing the mortar, add only as much water as necessary to obtain the right plasticity of the mixture, thus reducing the moisture content in the wall.
How to remove efflorescence on the clinker?
If, however, efflorescence emerges on the façade, it is essential first to identify the cause, and only then remedy the consequences. Otherwise, the cleaning will seem like ploughing the sands. In order to remove efflorescence permanently, it is necessary to locate the places through which the moisture penetrates into the wall. The main suspicious signs include chipped or cracked components. Once all potential sources of the problem have been firmly sealed, the façade cleaning can commence.
It is important not to begin the work with wet cleaning, as this will cause a significant proportion of the salt to penetrate back into the wall. The cleaning should begin with wiping the façade with a dry brush to remove as much salt as possible. Then, the façade can be washed with warm water (using e.g. a pressure washer) to remove everything that has not been removed by the dry wiping. If there are still areas that have not been thoroughly cleaned, special efflorescence removers can be applied.
Once the façade is clean, it can be coated with a special clinker oil. It prevents the moisture from entering the structure, yet if water is still inside, it allows it to flow freely outside. Please consider that the oil may slightly darken the colour of bricks. For this reason, it is advisable to carry out a test on a small, inconspicuous area of the surface.
Efflorescence on clinker brick fence. How to remove it?
On a warm, sunny day, efflorescence can be dry-wiped using a medium stiff bristle (scrubber) brush as much as possible. The point is to mechanically remove as much salt as we can. If the efflorescence is immediately treated with water, a large proportion of the salt will penetrate back into the wall. Water is used to wash off the salt residue that has not been removed by dry brushing. It is advisable to do this on a warm day so that the moisture can quickly evaporate from the façade. Once the wall is clean and dry, the clinker is coated with a special clinker oil. Clinker oil prevents moisture (which is the catalyst for efflorescence formation) from entering the structure, or, in case moisture is within the structure, it allows it to find its way out of the wall.
The oil is applied over the entire fence surface (bricks and joints) using a paintbrush. It is recommended to repeat this procedure twice. After this treatment, the efflorescence will gradually disappear. It should be remembered that clinker oils tend to slightly darken the colour of bricks; therefore, prior to applying the product onto the clinker, it is advisable to carry out a test on a small area of the surface to make sure that the effect will be acceptable.