Tile Porosity
Tile porosity stands for how much moisture a tile can absorb. It has a direct impact on the tile’s durability, strength, longevity, appearance, and resistance to environmental conditions. Tile porosity is expressed in water absorption percentage and is closely related to the tile’s internal density level.
Tiles that have a low porosity are denser and have a higher moisture resistance rating. Such tiles with low water absorption rate are typically suitable for wet spaces and outdoors.
Tile Porosity: Causes and Factors
Tile porosity is determined during the manufacturing process and is an internal characteristic of the tile. The number of microscopic capillaries and air bubbles present in the material influence the tile's ability to absorb water.
- Material Composition: Minerals and natural clay contain particles of various sizes. This affects the size of air bubbles and compaction. Refined materials generally created low porosity tiles.
- Firing Temperature: Higher firing temperatures are generally recommended to remove internal voids to create a dense and low porosity tile.
- Compaction and Pressing: High pressure and compaction increases density level and reduces the presence of pores within a tile.
- Glazing (Surface Layer): Being a surface treatment, glaze can reduce surface absorption, however it does not eliminate the internal tile porosity completely.
Classification of Tiles
Water absorption rate is used to group tiles into different categories. This categorization helps in determining the strength, stain susceptibility, and utility of the tiles. The classification system works in tandem with the porcelain density classification standards.
| Classification | Key Characteristics | Typical Materials | Best Use |
|---|---|---|---|
| Impervious (≤ 0.5%) | Very high density, minimal absorption, strong moisture resistance | Porcelain | Showers, pools, outdoor areas |
| Vitreous (0.5% – 3%) | High density, low absorption, reliable durability | Glazed ceramic, porcelain | Kitchens, living areas |
| Semi-Vitreous (3% – 7%) | Moderate density, noticeable absorption | Ceramic | Indoor floors and walls in dry or moderately moist areas |
| Non-Vitreous (> 7%) | Low density, high absorption, porous structure | Ceramic | Dry walls, decorative use |
The lower the tile porosity, the higher the tile’s resistance to moisture, staining, and environmental stress, resulting in better long-term performance.