Gato Ceramics & Japanese Food
Glossary
Celadon glaze is a transparent blue-green glaze valued across East Asia for centuries. Its color develops through reduction firing, a condition in which the fire in the kiln consumes much of the available oxygen. The blue-green tone comes from the small amounts of iron in the glaze that change color under these oxygen-poor conditions.
Celadon from Hiroyumi Suzuki
With small amount of iron, the glaze becomes a pale bluish white; with almost none, it remains a clear glaze like that used for white porcelain. Too much iron, or weak reduction, can shift the color toward yellow, brown, or dark. Celadon therefore relies on a careful balance of iron content, firing condition, and glaze thickness.
Historically, many celadon glazes were simple ash glazes made from plant ash and mineral materials such as feldspar.
Plant ash contain many impurities such as phosphates and iron, which affect the final outcome of the glaze. While working with minerals like limestone and Iron Oxide instead of ash, one can create more precise and stable composition of glaze, but it will reduce the natural variation that comes from working with organic materials. Potters often experiment with different wood as ash sources to influence the final tone.
The thickness of celadon glaze can also influence the outcome. A thicker layer can trap tiny bubbles within the glassy melt, scattering light and creating deeper, more complex color. The hue intensifies with thickness, and some potters apply multiple coats before firing to build this depth. Thick glaze layers may also develop natural crackle (craze) as they cool, adding to the aesthetic of celadon.
Simple in materials yet sensitive to every stage of production, celadon glaze reflects a long tradition of careful adjustment and close observation. Its quiet blue-green surface continues to be appreciated for the depth and calm it brings to ceramic form.
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