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Efflorescence on Clay Tiles - Cause and Remedy

Efflorescence is the formation of white powdery coating on the top of a clay tile. The word literally means ‘to flower’. Here in this article, we shall describe what efflorescence it, the causes and remedy. 

The Background Story

Clay tiles, by nature are porous. The level of porosity depends on the clay and firing temperature. For example, a good clay tile that has 12-14% water absorption has around 24% open porosity. This allows the building to ‘breathe’ through the tile. This porosity means that water or any similar liquid can be absorbed into the clay tile and spread throughout the clay body. 

When the water comes into contact with air, it has a chance to evaporate. If the water is very pure, it will leave no residue on evaporation. But this is almost never the case. Water contains many impurities like calcium and magnesium salts and minerals. These impurities can not evaporate with the water. So, they are left behind when water becomes vapour. This ‘left-behind’ salts appear visibly as white powdery ‘bloom’ on the surface of the tile. 

Efflorescence immediately after Construction

During construction, when the tiles are laid on the floor, the cement mortar may still be wet. The adhesive used for pasting the tile may also contain water. All this water needs to dry out. This evaporation happens through the clay tile. Being a porous material, the clay tile absorbs water from the bottom. This slowly spreads to the full body of the clay tile. When it reaches the surface, it comes in contact with the atmospheric air and evaporates. This makes any salts that are present in the water, cement mortar or the clay tile to migrate to the exposed top area of the tile. 

This efflorescence is temporary and will stop as soon as all the construction water has evaporated. To remove this, just wipe with water or a mild tile cleaner. Once removed, it will not reappear again.

Efflorescence that keeps re-appearing

If the efflorescence is re-appearing again and again after cleaning, it means that he process is being sustained by a water source. Locating the source of water is the most tricky part, as it is not recognisable easily. It may be a broken pipe inside the wall, a leaking coupling or fitting, water tank that is not sealed etc. Brick walls also conduct water from the floors above and conduct them to underneath the tiles.

Here are the steps to fix the situation:

1. Remove the source of water

Fix the leaking pipe, water proof the ceiling or water tank etc. This is very important  not just to prevent efflorescence but to protect the building from severe damage due to corrosion.

2. Clean the tile surface

First try scrubbing with plain water. If it is still visible on drying, try using tile cleaners of increasing strength. An excellent organic cleaner would be lime juice. Buy old, discarded lemons from vegetable sellers in a few hundreds. Wet the floor first with plain water to prevent the juice from being absorbed into the tile. Then, cut the lemons and squeeze the juice on to the tile surface. You can use a soft scrubber. Scrub until the powers are removed. Wash with plain water again and let try. Observe if the power reappears on drying. If it is not removed, it means the salt is too strong for the cleaner. Try repeating again increasing the concentration of the cleaner, soaking time and scrubbing. 

If this mild cleaner does not work, you have to use a stronger cleaning solution. Be very careful not to corrode the tile. Please do get in touch with us for specific recommendations.

If the efflorescence is removed by cleaning but the salts reappear a few hours or days later, it means there is still water under the tile. Either the leak is not yet fixed or the mortar has still not dried out. Removing a few tiles and checking will confirm this. The only solution is to make sure the water source is stopped and wait for the building to dry up and repeat the cleaning.

3. Prevent Efflorescence by sealing the tile

You can prevent Efflorescence by using an under-tile sealer. This sealer has to be applied before laying the tile. Please do get in touch with us for recommendations.