Blending black clay from Loreto with white clay from San Mateo, potters tread, throw, and biscuit-fire vessels in vaulted ladrillo kilns before dipping them in opaque milky tin-oxide glaze. 1
Strict Denomination of Origin rules allow only six mineral pigments prepared in-house—cobalt blue, antimony yellow, iron red, manganese black, copper green, and orange. Inscribed by UNESCO in 2019. 1
