lasituspoltto

Lasituspoltto, often translated as "glaze firing" or "vitrification firing" in English, is a crucial stage in the ceramic production process. It refers to the high-temperature firing of ceramic ware after a glaze has been applied. The primary purpose of this firing is to transform the applied glaze into a glassy, impermeable layer that bonds permanently with the ceramic body. This process is essential for creating functional and decorative ceramic objects.

During the lasituspoltto, the temperature is raised to a specific point, known as the maturation temperature of the glaze. At this temperature, the raw materials within the glaze, such as silica, fluxes, and colorants, melt and fuse together. The interaction between the molten glaze and the ceramic body causes a chemical and physical bond to form, ensuring the glaze adheres strongly and does not peel or chip. This firing also causes the ceramic body itself to vitrify, meaning it becomes dense and non-porous, increasing its strength and durability.

The specific temperature and duration of the lasituspoltto vary greatly depending on the type of clay, the composition of the glaze, and the desired final properties of the ceramic piece. Different firing atmospheres, such as oxidation or reduction, can also be employed during this stage to achieve specific aesthetic effects in the glaze color and surface. Successful lasituspoltto results in a durable, aesthetically pleasing, and often waterproof ceramic object.