Water Absorption and Tiles: Myths Vs Facts!
Water absorption is an important property to consider when shopping for tiles, especially if you are planning to tile high traffic areas. In other words, a tile’s water absorption rate is directly related to its suitability for specific traffic conditions.
What is water absorption for tiles?
All tiles are classified into different types by their water absorption, which is the quantity of water they can absorb, expressed as a percent of their dry weight. MS ISO 13006 describes the standards for manufactured tiles, where the different types of tiles are categorised according to their respective water absorption rate:
|WATER ABSORPTION (%)||TILE TYPE||BREAKING STRENGTH|
|≤ 0.5||PORCELAIN TILES||1300N|
|>0.5 to ≤ 3||GRES FLOOR TILES||1100N|
|>3 to ≤ 10||CERAMIC FLOOR TILES||800N|
|>10||CERAMIC WALL TILES||600N|
Tiles with low water absorption, or below 0.5%, are categorised as porcelain tiles. Ceramic floor tiles have a water absorption rate of 3 to 10%, whereas ceramic wall tiles have a water absorption rate of more than 10% and are suitable specifically for walls.
What causes water absorption in tiles?
Ceramic and porcelain tiles are produced when a selection of raw materials are fired at high temperatures to produce a dense, hard, and strong tile. While both made from clay, porcelain tiles have fluxing agents like feldspar and talc added to their formulation and are pressed at much higher pressures and fired at much higher temperatures, all of which makes porcelain tiles much denser than ceramic tiles. This density also means that porcelain tiles are harder, stronger, and have better chemical resistances, which is why they are considered heavy duty tiles and suitable for commercial, outdoor, and high traffic area applications.
As you might imagine, when a tile is denser, there are fewer pores or tiny gaps within the tile’s body where water can be absorbed. This makes water absorption an excellent gauge of the density of a tile.
How is water absorption tested?
After tiles come off the production line, a sample goes through a series of tests to ensure its performance and compliance with existing standards. One of such tests is the water absorption test, where a dry tile is boiled in water for 2 hours and then soaked for another 4 hours to determine its water absorption rate.
There are a number of myths associated with water absorption and tiles, such as the following:
Tile Water Absorption Myth #1: Water Absorbed into Tiles Will Damage Them
There are some sources that claim that when water is absorbed into a tile’s body, the subsequent contraction and expansion of the water droplets in the tile’s body exerts force on the tile, which damages it, and causes more issues later. This is not true, as water absorption is not a phenomenon of installed tiles, but rather a test of a tile body’s density.
Tile Water Absorption Myth #2: Tiles with High Water Absorption are Also More Prone to Staining
The water absorption rating is a measure of the porosity of the tile’s body – but this does not mean that any staining agents would be absorbed into the tile body. In practice, most tiles come with an impervious glaze coat on their surface, which prevents staining even on tiles with high water absorption.
Tile Water Absorption Myth #3: Tiles with High Water Absorption Must Not Be Installed in Wet Areas
Branching off myth #1, it has been claimed that water damage is the main reason why tiles with high water absorption should not be installed in wet areas, such as poolsides, bathrooms, and outdoor areas. This isn’t true either, as ceramic tiles can be installed in such areas while performing perfectly well, with the caveat that tiles with
over 10% of water absorption should be limited to wall installations. The reason for this has little to do with water, however: ceramic wall tiles should be installed on walls only because their porous bodies may not hold up as well as other tiles under foot traffic. When selecting tiles for such wet areas, the main consideration should instead be on their slip resistance ratings.