Grog is a type of refractory clay that has undergone a high-temperature firing process to transform it into a more heat-resistant substance. After this process, grog is crushed into fragments of different sizes, from fine to coarse, and added to the clay body in order to improve several of its physical and thermal properties. One of the key functions of grog is to increase the strength of the clay body by reducing shrinkage during drying and firing. This is especially useful in the creation of large and complex pieces, such as sculptures.
In addition, grog is instrumental in improving the body's ability to withstand thermal shock, making it an essential ingredient for the manufacture of ceramics that will be exposed to sudden changes in temperature.
Another important benefit of grog is that it provides a rough texture to the clay body, which makes it an option for texturing the surfaces of the pieces. This rough texture is not only aesthetic, but can also influence the durability and functionality of the pieces, facilitating the adherence of glazes or engobes.
Interesting Fact
Clay bodys containing grog are ideal for the raku technique, as their resistance to thermal shock allows them to withstand rapid cooling without cracking.
Helpful Tip
If you are working on large-scale projects or parts that require stability, add 10% to 30% grog to the clay to improve strength. Keep in mind that the amount of grog will affect plasticity, so it is important to balance it properly.
