Scope:

Density, porosity, and specific gravity indicate the degree of maturation of a ceramic body. They are used to determine structural properties which may be required for certain applications. 

Test Procedure:

In ASTM C373, the test specimens are dried to constant mass by heating in an oven for a minimum of 24 h. They are then cooled in a desiccator. After that, they are weighed to determine their dry mass. The specimens are placed in distilled boiling water. The distilled water is unused, and it is sufficient that the test specimens are fully submerged. The mass ratio of water to test specimens is at least 3:1. The container is covered to minimize water loss through evaporation. Specimens should be immersed in boiling water for 5 hours. After that, the specimens are allowed to soak in the same distilled water for additional 24 hours. After 24 hours of soaking, the mass of each specimen, while they are suspended in water, is determined. A damp leather chamois is then used to remove all visible water droplets from the surface. After that, the specimen is weighed immediately.

Specimen size:

ASTM C373 describes the following specimen sizes:

Ceramic Whitewares: 

Minimum of five specimens are required. They should be unglazed. Sharp edges or corners should be removed. They must not contain any cracks. The individual test specimens should weigh at least 50 grams.

Ceramic Tiles and Glass Tiles: 

The specimens should not contain any visible damage or cracks before testing. Minimum five specimens are required. The specimens should be cut by scoring and snapping or sawing when impossible to score

Data:

Water absorption, bulk density, apparent porosity, and apparent specific gravity are reported. 

Conclusion:

ASTM C373 test method is used to determine water absorption, bulk density, apparent porosity, and apparent specific gravity of fired unglazed whiteware products, glazed or unglazed ceramic tiles, and glass tiles.