トラブル
If it cracks later, suspect slow cooling.
Japanese: 後日割れたら徐冷を疑う
If cracks appear several days after firing, suspect insufficient slow cooling. This is caused by residual stress resulting from insufficient annealing. Extend the slow cooling time according to the thickness of the piece.
If the piece remains intact during firing but cracks a few hours to a few days later, the cause is residual stress (insufficient cooling).
Check for distortion using a polarizing filter, and maintain the slow-cooling point while extending the cooling time.
If you hear a cracking sound a few days to a few weeks after firing, it’s a sign of insufficient slow cooling. Residual internal stress causes the piece to fracture due to temperature changes.
Next time, extend the cooling time according to the thickness. Be especially careful with thicker pieces.
Take your time to relieve the invisible stress. That alone can significantly extend the life of your work.
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.