Sagger
A sagger is a box made of refractory clay used inside kilns to contain and protect the glazed pieces during the firing process. These boxes are specifically designed to withstand the high temperatures of the kiln, preventing the pieces from coming into direct contact with the flames, gases or smoke generated during firing, which could negatively affect the glazing results. Being made of refractory materials, the saggers are able to withstand extreme temperatures without damage, allowing them to be reused in multiple firings.
The saggers are particularly useful in kilns with oxidizing atmospheres, where oxygen in the environment can cause alterations in the colors and effects of the glaze, or in processes where fire and smoke can have an undesirable impact on the quality of the glaze. By placing the pieces inside these refractory boxes, they are isolated from the direct effects of the kiln atmosphere, ensuring a more controlled firing and more predictable results.
In addition, gasses are also used in reducing atmospheres, where the aim is to control the effects of gases on the fired parts. In this environment, the low-oxygen atmosphere can influence the colors and characteristics of the glaze, and the use of saggers allows this environment to be managed in a more controlled manner, preserving the integrity of the glaze.Interesting Fact
First used in China during the Song dynasty, saggers were refractory vessels called "saggers", essential for protecting porcelain pieces in kiln firings. Thanks to this system, Chinese ceramists were able to produce exceptionally fine porcelain that was recognized worldwide for its purity, luster and unprecedented quality.Helpful Tip
Before loading the pot with your glazed pieces, be sure to cover the inside of the pot with a thin layer of refractory protection (e.g., a mixture of kaolin and alumina), so that the pieces do not stick together or leave glaze residue on the walls. Also, avoid stacking the pieces directly on top of each other and leave enough space between them for heat and gases to circulate properly, ensuring uniform firing and more predictable results.
