設計・制御
Heat Equalization (Stage B)
Japanese: 温度均一化（B段階）
Stage 2 of the firing program. This is the holding phase, designed to ensure uniform temperature inside the kiln. The standard procedure is to hold the temperature at approximately 500°C for 1 hour. The larger and thicker the piece, the longer this phase should be.
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Temperature Equalization (Stage B) is the second stage of the eight-stage firing program and is a hold phase designed to equalize the temperature within the kiln (§8.1). The standard for Bullseye COE90 is a 1-hour hold at around 500°C, but it is recommended to extend this time as the kiln size increases or as the pieces become larger or thicker. In the η-T-t trajectory notation (§2.2), this corresponds to “soak.” By ensuring that temperatures are uniform across different parts of the kiln—such as shelves, glass, and ceramic fiber, which have varying heat capacities—the kiln is prepared for the subsequent rapid heating (Stage C) to be carried out safely.
The importance of Stage B lies in eliminating temperature differences between the shelves of the electric kiln and the top, bottom, left, and right sides of the pieces. Rei Chikaoka (2021) recommends conducting a calibration test by placing samples in the four corners and the center of the kiln (Section 8.4); adjusting the duration of Stage B based on an understanding of the electric kiln’s specific temperature variations leads to a highly accurate firing design. In particular, for large kilns (60 cm or wider) and kilns with thin heater arrangements, temperature homogenization takes time, so it is not uncommon to extend Phase B from 30 minutes to 2 hours. The timing of the transition from Phase B to Phase C (rapid heating) determines the quality of the artwork.
Related Concepts
Gain an understanding of the entire temperature-rising phase, taking into account the initial heating (Stage A) (firing-stage-a), rapid heating (Stage C) (firing-stage-c), the 8-stage firing program (firing-program-8-stages), and the thermal diffusivity κ (thermal-diffusivity).
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.