Ceramic Tiles - Methods of Test, Sampling and Basis for Acceptance
2006 Edition

IS 13630 specifies minimum sample quantities based on tile size and test type. For tiles 48 mm or larger, a minimum of 7 test specimens is required, while tiles smaller than 48 mm but at least 18 mm require 10 specimens. For inspection lots, dimension testing generally uses 10 tiles, surface quality assessments require at least 30 tiles or an area of 1 m², and tests for other properties involve between 1 and 11 specimens depending on the parameter. These sample sizes ensure valid and statistically reliable testing outcomes.

The standard mandates cycling whole tiles 10 times between cold water at approximately 15°C and hot water near 145°C to simulate thermal shock. Tiles with varying water absorption levels may undergo different immersion procedures. After cycling, tiles are examined visually for cracks or crazing. The test report must document tile details, specimen count, number exhibiting crazing, and a descriptive record of findings. This procedure aligns with ISO 10545-9:2004 and ensures tiles can tolerate rapid temperature changes without damage.

Chemical resistance for unglazed tiles is evaluated by partially immersing specimens in selected chemical solutions for 28 days at room temperature. Following exposure, a visual examination assesses surface changes such as discoloration, surface degradation, or complete damage. The tiles are then classified into resistance categories ranging from no visible effect to total surface loss. The test report includes tile descriptions, chemicals used, observed alterations, and classification. This method provides a standardized approach to assess durability against chemical exposure.

Abrasion resistance is tested by subjecting dry tile specimens to abrasion under a rotating load for up to 12,000 revolutions. Mass loss is measured before and after 6,000 revolutions, while visual inspections are conducted at predefined revolutions to detect surface wear. Tiles are classified based on the number of revolutions at which failure becomes visible, ranging from class 0 (failure at 100 revolutions) to class 5 (failure beyond 12,000 revolutions). Passing class 5 requires additional stain resistance testing. Test reports detail specimen preparation, classification, failure revolutions, and mass loss.

Acceptance depends on the number of defective tiles found within the sample compared to predefined acceptance (Ac) and rejection (Re) numbers. Defects considered include glaze faults, surface depressions, specks, nipped edges, and dimensional deviations such as length, width, thickness, straightness, and flatness. If defects are less than or equal to the acceptance number, the lot is approved; if defects exceed the rejection number, the lot is rejected. Cases between these limits require a second sampling. This systematic approach ensures quality control consistent with IS 13630 and ISO 10545-2.