What is the primary purpose of adding grog to wet clay?

Adding grog to wet clay primarily serves the purpose of reducing shrinkage and warping during the drying and firing processes. Grog consists of pre-fired clay that is crushed into granular size, and its inclusion in the clay body helps to create a more stable mixture.

When wet clay dries, it tends to shrink, which can lead to cracking or warping as it loses moisture. The addition of grog mitigates this problem by providing structure and reducing the overall shrinkage rate of the clay. The larger particles of grog create spaces within the clay, allowing for better airflow and moisture evaporation as the piece dries. This leads to reduced internal stresses and a lower likelihood of deformation.

The other options highlight aspects of clay manipulation that do not directly relate to the primary benefits of grog. While it may have some impact on color, plasticity, or firing temperature, the most significant and intentional use of grog is to enhance the integrity of the clay by minimizing shrinkage and warping.