Why did Japanese potters value irregular shapes and accidental-looking glaze effects?

In Japanese pottery, the appreciation for irregular shapes and accidental-looking glaze effects is deeply rooted in the aesthetic philosophy of wabi-sabi, which finds beauty in simplicity, imperfection, and impermanence. This preference reflects a profound respect for nature, where the cycle of birth, fruition, decay, and death is viewed as a source of spiritual insight.12

Japanese potters sought to create objects that appeared uncontrived, much like natural stones. To achieve this, they often:34

• Emphasized the Maker’s Hand: Potters frequently left finger ridges and tool marks on vessels to reveal the human touch, rather than smoothing them away.34
• Encouraged Asymmetry: Hand-modeling was practiced long after the wheel was known, as potters intentionally sought out irregular and asymmetrical forms.34
• Cultivated Accidental Glazing: Glazes were often applied irregularly and allowed to run in streaks. Techniques such as rapid cooling in raku ware or reduction firing were used to create unique, unpredictable surface variations, bubbles, and fissures, such as "dragon skin" or "lizard skin" textures.534

These aesthetic choices were heavily influenced by the tea ceremony, where tea masters acted as arbiters of taste, valuing utensils that felt natural, fit the hand well, and exhibited a beauty that was not cold or overly perfect.342