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Home How do I clean "white deposits" from my balcony tiles?

How do I clean "white deposits" from my balcony tiles?

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Some balcony tiles may experience a "white deposits" which is usually due to efflorescence caused by the dissolving of calcium hydroxide which forms as part of the setting process of the underlying cement mortar of the tilers bed by rain water that enters the bed. 

The water carrying the dissolved calcium hydroxide either falls by gravity to emerge at the face of riser tiles or it rises up through the tile joints in the process of evaporation.  Tiles are dense, so the moisture travels up the joints in a process similar to putting a sheet of plastic on the grass and having moisture condense on the underside.

As the moisture evaporates, the calcium hydroxide reacts with carbon dioxide in the air to form calcium carbonate which forms the "white deposits".

Calcium carbonate is easily dissolved in acid and thereby removable.  The problem is that more efflorescence will form until the calcium hydroxide is depleted.


The surface of the affected tiled area should be swept clean.  Any white calcareous residues should be scraped off with a blade.  A stainless steel wire brush can also be used with care.  Any further residues should be swept up and removed.

The area should be washed with a neat solution of Aquamix Eff-Ex according to the manufacturer's instructions.  This is an especially safe EDTA ph7.4 product which helps to make calcium hydroxide insoluble.

Alternately, add 5 parts of water to 1 part of phosphoric acid and apply to the area and scrub with a nylon broom.  The area should then be thoroughly rinsed with water and allowed to dry.

The surface of tiles should then be sealed with 2 coats of penetrating sealer such as Aquamix Ultra-solv or Spirit premium Seal.  Tp stop water penetration to the tiling system this sealing should also include the skirting tiles.

The sealer will need to be applied after approximately 5 years, to test when this is necessary sprinkle a few drops of water on the tile joint and see if it is absorbed, if so, it is time to re-seal.


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