Why are pores and glass content important in clay products that resist chemicals and water?

In clay products, the management of pores and glass content is essential for achieving resistance to chemicals and water. The primary goal of firing these materials is to achieve consolidation and reduce porosity, which directly enhances impermeability to fluids.1

The Role of Glass Content

During the firing process, clay undergoes partial vitrification, where crystalline silicate compounds melt to form a glassy, noncrystalline structure. This glassy phase facilitates liquid-phase sintering, which promotes the rearrangement of particles and the filling of voids. By creating a denser structure, the glass content effectively seals the material, preventing the penetration of water and corrosive chemical substances.1

The Importance of Porosity

Porosity refers to the air spaces within the material. While some porosity can be beneficial for thermal shock resistance by blunting cracks, it is generally undesirable for products intended to resist chemicals. A high-density structure with minimal pores is necessary to prevent corrosive substances from infiltrating the material. By controlling the firing time and temperature, manufacturers can optimize the balance between glass formation and residual porosity to ensure the final product remains durable and impermeable in harsh environments.21