Double firing
Double firing in ceramics is a process that involves two stages of firing a ceramic piece to improve its physical and aesthetic properties. The first firing, known as bisque, bisque or bisque firing, is carried out at a lower temperature (generally between 800°C and 1000°C) to convert the clay into a porous, hardened state that can be handled without breaking. During this phase, the piece loses the remaining moisture and becomes more resistant to handling, allowing additional decorations to be applied without compromising the structure of the piece.
After the first firing, the bisque piece can be decorated with paints, glazes, engobes or other decoration techniques. These decorations are applied to the surface of the piece before the second firing. The second firing, known as glazing, is carried out at a higher temperature (generally between 1200°C and 1300°C) to vitrify the glaze applied, creating a hard and impermeable vitreous layer that protects the piece and enhances its aesthetic appearance. This double firing process allows for more complex and detailed finishes, as it separates the modeling and decoration stages, facilitating greater control over the final result.
Double firing also improves the durability and resistance of ceramic pieces, since the vitrification of the glaze increases impermeability and wear resistance. In addition, this process allows a greater variety of finishes, from smooth and shiny surfaces to rustic and matte textures, depending on the glaze formulation and firing conditions.Interesting Fact
The double firing process was a crucial innovation in the history of ceramics, making it possible to separate the modeling and decoration work from the glazing process, which in turn increased the versatility and quality of the ceramic pieces produced.Helpful Tip
To achieve a successful double firing, make sure that the first firing is complete and uniform, avoiding the presence of residual moisture that could cause cracking or bursting during the second firing. In addition, carefully control the glaze application after bisque-firing to ensure uniform coverage before glazing.