Calcined Kaolin
Calcined kaolin is a form of kaolin that has been heat-treated to remove chemically bound water and improve certain physical and chemical properties of the material. This calcination process, which is generally carried out at temperatures of 500°C to 1000°C, transforms kaolin into a more stable and less plastic material, making it ideal for specific ceramic applications.
In ceramics, calcined kaolin is mainly used as an ingredient in glazes and clay bodys. In glazes, it acts as a source of alumina and silica, improving hardness, heat resistance and stability during firing. It also helps prevent glaze run-off in vertical pieces, ensuring a uniform finish. In clay bodys, it is used to reduce shrinkage during drying and firing, minimizing the risk of deformation and cracking.
Calcined kaolin is especially useful in technical and industrial ceramics, where a heat-resistant and chemically stable material is required, such as in the manufacture of refractory bricks, thermal insulators and ceramic electronic components. In addition, due to its whiteness and stability, it is a key ingredient in fine porcelains and high-quality decorative ceramic products.Interesting Fact
Calcined kaolin originated as a by-product of the paper industry, where it is also used as a coating to improve the whiteness and opacity of paper. In ceramics, its development has made it possible to overcome some of the limitations of natural kaolin, such as its high shrinkage.Helpful Tip
For best results in your glazes or clays, mix calcined kaolin with raw kaolin in appropriate proportions according to the desired characteristics. Be sure to sift the material before use to ensure even distribution. Store it in a dry place because, although it is less plastic than natural kaolin, it can absorb moisture.
