For the manufacture of enamel pigments, traditional solid-phase reaction methods are generally used, as well as liquid-phase synthesis methods and microwave sintering processes.
The well-mixed and dried batch materials are loaded into a refractory sagger for calcination in open, covered, sealed, loosened and compacted ways according to the requirements of different types of pigments. Calcination is to synthesize stable colored minerals. The calcination temperature, calcination time, and calcination atmosphere are determined by the type and formula of the pigment, and have a great influence on the grade of the pigment. Calcining is usually divided into two types: high temperature and low temperature. The synthesis temperature of most enamel pigments is 1000-1300 degrees Celsius, the sintering time is usually 10-20h, and the average firing cycle is 24h. The advanced pigment sintering process is microwave firing, and the firing cycle does not exceed 8h.
Except for some pigments using reducing atmosphere, oxidizing atmosphere is usually used for sintering. Generally, one-time sintering is used. For some special varieties, two or even three-time sintering is also used.