The primary flux in ceramic bodies — lowers the melting/vitrification temperature from ~1,650°C to 1,150–1,250°C. Forms a highly viscous, stable glassy phase at firing temperature that fills interstitial pores and bonds mineral grains. Higher K₂O gives greater viscosity — preferred for fine porcelain, bone china, and high-strength floor tiles where shape retention during high-temperature firing is critical. Also contributes Al₂O₃ (hardness) and SiO₂ (chemical durability) to the fired body simultaneously. Best high-purity K-feldspar: K₂O ≥10%, Fe₂O₃ <0.10%, brightness ≥85%.

The second major flux type — melts at lower temperature than K-feldspar (~1,100–1,180°C), producing a less viscous, more fluid melt that wets and fills body pores at lower kiln temperatures. Preferred for wall tiles (lower-fire), sanitaryware casting slips, frits and glazes requiring good flow. Often used in combination with K-feldspar — blending allows fine-tuning of vitrification temperature and fired body properties at optimised cost. Best soda feldspar: Na₂O ≥8%, Fe₂O₃ <0.15%, brightness ≥82%.

The refractory skeleton of the ceramic body — does not melt during firing (melting point 1,713°C), instead forming a rigid crystalline framework that resists shrinkage, warping, and deformation. Controls the thermal expansion coefficient of the fired body (critical for glaze fit). SiO₂ contributes hardness, abrasion resistance, and dimensional stability. In glazes, quartz is the primary glass network former. Fe₂O₃ <0.10% required for white tile body; <0.05% for premium porcelain and glazes. Best Rajasthan quartz: SiO₂ 99.0–99.5%, brightness 90–96%.

The primary white-burning clay — a high-purity, relatively low-plasticity phyllosilicate that fires to a bright white at temperatures above 1,000°C. Provides Al₂O₃ (hardness, refractoriness), SiO₂ (glass network), and controlled plasticity for body forming. The highest-purity kaolins (Fe₂O₃ <0.3%) are essential for porcelain and bone china whiteness. Less plastic than ball clay — typically combined with ball clay to achieve both whiteness and workability. China clay (kaolinite-rich) is the standard term used in the UK and internationally for high-purity kaolin from Cornish or equivalent deposits.

The plasticity engine of the ceramic body — a highly plastic, fine-grained sedimentary clay containing kaolinite, organic matter, and accessory clay minerals. Ball clays give the wet body the workability, green strength, and forming ability needed for extrusion, jiggering, slip casting, and pressing. The tradeoff is colour — ball clays fire grey to buff rather than white due to organic matter and iron content. Premium ball clays (UK Devon/Dorset, Germany, Ukraine) fire near-white and are essential for fine ceramics. Standard ball clays for tiles/sanitaryware are abundant globally.

Talc provides MgO flux at lower temperatures than feldspar — used in wall tile bodies (earthenware) to enable full firing at 1,050–1,100°C. Also reduces thermal expansion coefficient. Calcium carbonate (CaCO₃) contributes CaO flux — used in fast-fired single-fire wall tiles (Italian-style). Wollastonite (CaSiO₃) provides CaO + SiO₂ without CO₂ evolution. Each minor mineral modifies the body's firing behaviour, dimensional shrinkage, and mechanical properties.