Locally processed raw materials are essential for producing traditional colored glazes.
- Glaze Ash (釉灰)
- Primary Component: Calcium oxide (CaO)
- Function: Acts as the main flux for traditional colored glazes (e.g., copper-red, iron-celadon, mirror-black, tea-dust).
- Preparation Method: See Glaze Ash Firing Process in Section 2.
- Secondary Ash (二灰)
- Composition: Lower calcium oxide content than glaze ash.
- Source: Residue from washed glaze ash, aged and finely ground.
- Use: Similar to glaze ash as a flux.
- Kiln Slag (窑渣)
- Role in Glazes: A traditional auxiliary material in copper-red glazes, containing oxides of calcium, magnesium, iron, titanium, manganese, cobalt, and phosphorus.
- Special Effect: Crucial for creating blue streaking in copper-red flambé glazes.
- Origin: Produced in Jingdezhen’s historical “Cuo Kilns” (basic porcelain kilns fueled by fern grass).
- Appearance: Gray-black clumps—a fusion of clay bricks, wood ash, and volatilized glaze from blue-and-white porcelain firing.
- Processing: Collected, cleaned of dust, crushed, and sieved before use.
