釉里红
Copper-based pigment applied to porcelain body before glazing and high-temperature firing. Technically demanding requiring precise atmospheric control. Characteristic of Hongwu, Xuande, and Qing imperial revivals.
Technical Structure
Copper-based pigment is painted onto the unfired body and sealed beneath a single transparent glaze, fired once at high temperature. Copper red is one of the most difficult pigments to control in the kiln: it requires a narrow reduction atmosphere to hold a stable red, and will shift to grey, brown, or vanish if firing conditions drift even slightly outside that range.
The technique appears in Yuan-dynasty production and recurs at technically ambitious moments across Chinese ceramic history — notably the Hongwu and Xuande reigns of the early Ming, and again as a deliberate revival during the Qing dynasty when kilns sought to demonstrate mastery of historically difficult techniques.
Because successful copper red is so firing-dependent, the clarity and evenness of the red is itself the primary indicator of technical success — many historical attempts survive with muted, uneven, or greyed colour, which is part of why a clean, stable red is notable rather than assumed.