Flux — in tile production, refers to a material or ingredient that is added to ceramic compositions to lower the melting point of the clay body or glaze. It aids in the fusion of various components during the firing process, allowing them to melt and form a glassy surface or bond together.

Commonly used flux materials in tile production include feldspar, borax, and various metal oxides. These fluxes contribute to the desired properties of the ceramic, such as improved workability, increased fluidity, and enhanced adhesion between layers.

The addition of flux in the correct proportion is crucial for achieving the desired results in terms of colour, texture, and durability of the final tile. It helps to create a stable and uniform glaze or vitrified surface, ensuring the tile's resistance to water absorption, chemical attack, and wear. The specific type and amount of flux used depend on the desired firing temperature, clay composition, and desired visual and technical characteristics of the tile.