Explore the unique wood-fired kiln effects of Japanese Bizen pottery - goma sesame-spots, hidasuki red cords, botamochi ghost circles, Ao-Bizen blue tones and more. Each piece is one of a kind.

1. Goma

In wood-fired kilns using red-pine logs, ash drifts and settles on the ceramic surface during firing. When that ash melts at high temperatures, it forms a kind of “natural glaze.” In Bizen ware, this speckled effect resembles scattered sesame seeds and is called goma.

2. Kasegoma

Among the variations of the goma effect, kasegoma occurs when ash dust adheres to the surface but does not fully melt or vitrify. These pieces are often located in hidden corners of the kiln, away from direct flame or heavy airflow. 

3. Hi-kaburi

During a typical Bizen firing, when kiln temperatures reach up to 1200 °C, ash adhering to some pieces burns, melts slightly, and forms a coarse “pumice-like” layer on the surface, often termed hi-kaburi. The effect emerges from the interaction of resin in the pine wood and organic impurities in the clay. 

4. Tamadare

When the sesame-seed-like ash (goma) melts more completely and flows into streaks or drips, the effect is called tamadare. These flowing lines add a dynamic, liquid quality to the surface texture.

5. Koge

Ash and dust that fail to melt fully and instead char on the surface remain rough and blackened. This is known as koge - literally “burnt” - and is prized for its rugged texture and sober depth.

6. Kabuzeyaki

In this technique, the potter covers the mouth of a sake bottle (tokkuri) with another piece of pottery before firing. The covered section is shielded from flying ash and flame, preserving its original clay color in contrast with the exposed body. This deliberate contrast is called kabuzeyaki.

7. Botamochi

Originally, when pieces were stacked in the kiln, those beneath a round plate or object would be shielded from ash fallout. The result is a round, blush-red mark on the surface, known as botamochi (after the Japanese rice-cake). These “ghost circles” are now celebrated in Bizen as a mark of individuality.

8. Nuke

By carefully arranging ware in the kiln, the potter can create pockets where ash does not settle and flame does not strike directly. These “hidden” zones yield unmarked surfaces with natural clay tones - a condition known as nuke (“missing”) and prized for its purity.

9. Hidasuki

A vivid red-cord pattern is produced when rice straw is wrapped around a piece before firing. The alkaline in straw combines with iron in the clay, creating scarlet, orange, gold, silver or black tracings, known as hidasuki. The technique is among Bizen’s most celebrated kiln-effects.

10. Hiiro (Scarlet Red)

The richly radiant red seen on certain pieces is called hiiro. When the red deepens to a purple tint under reducing conditions, the color is known as shiso-iro (perilla-leaf purple).

11. Sangiri

The term sangiri refers to a dual-tone flame marking: two overlapping fire-blush tones created where flame streamed directly across the surface. It is one of the most difficult kiln-effects to achieve consistently and thus one of the most highly valued.

12. Korogashi

Korogashi (“rolling burn”) describes pieces laid flat or angled in the kiln floor. Often buried in ash or directly in the zone where logs are stoked, they are subject to intense conditions and rarely emerge unscathed - the risk magnifies their uniqueness.

13. Ishihaze

Tiny stone fragments embedded in the Bizen clay may explode under high temperature, causing small crater-like pits on the surface. Rather than being considered a flaw, these are accepted and celebrated as ishihaze -“stone burst” - a visual metaphor of landscape after a volcanic eruption. 

14. Ao-Bizen (Blue/Black Bizen)

When ware is protected from ash and flame (for example buried or placed in a low-oxygen zone), strong reduction can produce an intense blue-black finish. This rare result, known as Ao-Bizen, is highly prized for its midnight-hued depth.

15. Shio-Ao / Shokuen-Ao (Salt-Blue)

In some firings, salt is introduced into the kiln so that its alkaline vapours settle on the ware, creating a salt glaze effect. The resulting fine, smooth blue-green surface is called shio-ao (“salt-blue”) and distinct from Ao-Bizen. These salt-influenced wares are rarely seen outside Japan.

16. Kuro-Bizen (Black Bizen)

Some pieces are placed under layers of sand or ash, with minimal exposure to flame, creating a reduced-oxygen environment. The resulting deep black surface is referred to as kuro-bizen (“black Bizen”) and is prized for its quiet gravity.