Kiln furniture refers to the refractory components used to support and protect ware during the firing process. In gas-fired kilns, kiln furniture directly determines loading density, temperature uniformity, and energy consumption. Although kiln furniture comes in various shapes, it can be broadly categorized by function into three types: load-bearing components, supports, and protective containers.
Load-bearing components are flat elements upon which the ware is placed directly. In gas-fired shuttle kilns, tunnel kilns, and roller-hearth kilns, the most common load-bearing components are kiln shelves (also known as batts or plates) and setter plates. For flat items such as Zellige tiles, grooved setter plates or specialized trays—refractory boards that have been machined to include slots or holes—are typically used. These features not only reduce weight but also allow hot air to circulate beneath the ware, which helps ensure uniform heating and cooling. Cordierite-mullite kiln furnitures is the standard material for such load-bearing components, as it possesses a low coefficient of thermal expansion (typically around 2.1–3.1 × 10⁻⁶ K⁻¹ below 1000°C) and the thermal shock resistance required to remain intact through repeated, rapid heating and cooling cycles.
Supports form the load-bearing structure beneath the kiln shelves. Cordierite posts (or pillars) are vertical refractory columns used to support kiln shelves at various heights, while beams are placed between these posts to support large-format shelves or bear heavier loads. In gas-fired tunnel and roller-hearth kilns, where greater strength is required or firing temperatures exceed the operational range of cordierite-mullite materials, posts and beams are typically made from silicon carbide or mullite-bonded materials. By combining posts, beams, and kiln shelves, a stable, stackable superstructure can be constructed on the kiln car, thereby maximizing the volume of ware that can be loaded during each firing cycle. Protective containers, known as “saggars”—box-like refractory vessels—are used to shield ware from direct exposure to flames, combustion exhaust gases, or other forms of contamination. In gas-fired kilns, saggars isolate glazed or environmentally sensitive products from the kiln atmosphere, thereby enhancing the surface quality of the finished pieces. For smaller items or products that require stacking, ring-shaped or lidded saggars are commonly employed.
The specific type of kiln furniture selected depends on both the kiln design and the nature of the products being fired. In the production of Zellige tiles—typically fired in gas-fired shuttle kilns at temperatures between 800°C and 1,000°C—the use of slotted cordierite-mullite kiln furniture, combined with support posts and lightweight batts, offers an optimal balance between thermal shock resistance, loading density, and service life. In processes requiring rapid cooling, the low-expansion properties of the cordierite phase are particularly advantageous, as they effectively reduce the risk of the kiln furniture cracking during the cooling phase.
Kerui Refractories supplies a wide range of cordierite-mullite kiln furniture and silicon carbide kiln furniture. Please feel free to contact us for inquiries!