Shrinkage cracks in clay tile are caused by what factor?

Shrinkage cracks in clay tile are primarily caused by differential drying rates between the surface and core during the manufacturing process. When clay tiles are formed and begin to dry, the outer layers tend to lose moisture faster than the inner core. This uneven drying can lead to the formation of cracks as the outer surface shrinks more quickly than the inner material, resulting in stress that ultimately manifests as visible cracks on the surface.

Understanding this phenomenon is crucial as it emphasizes the importance of maintaining uniform drying conditions in the manufacturing of clay tiles to prevent defects. The other factors listed, while they may affect the quality of the clay tile in various ways, do not specifically focus on the drying process and its impact on cracking.