Why is water absorption so important?
Why is water absorption so important in tiles?
Water absorption rates are the most important measurement of a tile. Water absorption measures how much moisture a specific type of tile is likely to absorb on an ongoing basis. Some types of tile may crack if the moisture penetration is too high. In general if the tile has a low water absorption, like porcelain, the durability and strength are higher. Low water absorption restricts the amount of water that may cause failure by cyclic salt attack and freeze thaw. The water absorption percentage reflects the density of the tile body. Water absorption is also directly related to the suitability for interior or exterior applications. For exterior applications, the selected tiles should have a low water absorption rate, especially in climates subjected to heavy rainfall and freezing and thawing cycles. A low water absorption rate also enables a tile to resist food or beverage stains.
Testing for water absorption determines the apparent porosity and relative density as a means to classify ceramic tiles according to the international standard ISO13006-10545/98. There are four categories:
B2b. Non-vitreous - Low density, High water absorption of more than 6.0% (Ceramic)
B2a. Semi-vitreous - Medium density, Medium water absorption of more than 3.0%, but less than 6.0% (Ceramic)
B1b. Fully Vitrified - High density, Low water absorption of more than 0.5%, but less than 3.0% (Gres Porcelain / Ceramic)
B1a. Impervious - Extremely high density, Very low water absorption of less than 0.5% (Porcelain)