Ceramic Tiles-Methods of the test, Sampling and Basis of Acceptance, Part 2: Determination of water absorption (see IS 13630: Parts 1 to 15)
2006 Edition

The process begins by drying the tile sample to a constant mass in an oven, then recording its dry weight. Next, the tile is fully submerged in water and boiled for a specified duration, followed by cooling while still immersed. After removing surface water without drying the pores, the wet weight is recorded. Water absorption percentage is then calculated by comparing the increase in mass relative to the dry mass, ensuring assessment of the tile's porosity and durability.

For testing, the standard typically requires 10 intact tiles per type if the tile's surface area is 0.04 m² or less. For larger tiles exceeding 0.04 m², only 5 whole tiles are needed. If individual tile mass is below 50 grams, multiple tiles should be combined to create a test specimen weighing between 50 and 100 grams. This ensures the test samples are statistically valid and representative.

The test requires a drying oven to achieve constant dry mass, a precision balance capable of measuring to 0.01 grams, a water container large enough for full tile immersion, and a boiling setup. Additionally, wire loops, halters, or baskets made from corrosion-resistant materials are used to suspend tiles underwater during boiling and cooling phases. A timer and absorbent cloth are also necessary for timing procedures and removing surface moisture before weighing.

Bulk density is determined by dividing the dry mass of the tile by its volume, which includes the tile's pores. The volume is calculated from the difference between the dry mass and the mass of the tile suspended in water. The result is expressed in grams per cubic centimeter (g/cm³). Test reports must include individual bulk density values for each tile as well as the average for the batch.

Weighing accuracy is vital and must comply with specified tolerances depending on tile mass. For tiles up to 100 grams, the balance must measure within 0.02 grams accuracy; for 101 to 500 grams, within 0.05 grams; from 501 to 1,000 grams, within 0.25 grams; from 1,001 to 3,000 grams, within 0.50 grams; and for masses above 3,000 grams, within 1 gram. Tiles under 50 grams should be grouped to meet the minimum specimen mass of 50 to 100 grams to ensure measurement precision.