【Japanese Pottery】Rakugama Kiln: The Intimate Rising‑Flame Kiln for Masterful Tea Bowls

Table of Contents

• 1. Raku Kiln (楽窯) Azuchi‑Momoyama Period–Present: Rising Flame Type
• 2. Strengths and Weaknesses of the Raku Kiln (楽窯の長所と短所)

1. Raku Kiln (楽窯) Azuchi‑Momoyama Period–Present: Rising Flame Type

The Raku kiln (楽窯) is a single‑chamber kiln developed from the Momoyama period onward for firing individual Raku ware. Raku ware was created under the supervision of tea master Sen no Rikyū and first fired by tile craftsman Chōjirō (長次郎) to produce tea utensils for the Japanese tea ceremony.

The Raku family, beginning with Chōjirō (also recorded as Asajirō), has continued producing Raku tea bowls for over 400 years, now into its 15th generation. Raku ware is universally recognized in the tea ceremony world.

In 1736, during the era of the sixth-generation Raku potter Sanyū (左入, 1685–1739), the two‑volume manual Rakuyaki Hinō (楽焼秘嚢) was published, documenting Raku kiln construction and firing techniques. The first volume’s “Method for Building a Kiln” recommends constructing the kiln from red Raku clay—a low‑plasticity, yellow‑tinged clay—and illustrates a cylindrical kiln with a removable lid and three flue holes at the top.

The kiln’s cylindrical form is built by arranging three 120° refractory panels into a circle. Fuel—traditionally charcoal—is replenished by removing the lid, which includes a peep hole (色見穴) for monitoring the interior.

In a modern Raku kiln, the three panels are constructed from refractory clay or firebrick. The panels form an arch sealed with refractory mortar. Charcoal placed on the kiln floor burns beneath a stainless‑steel support that holds the ware, requiring each piece to be enclosed in a sagger (匣鉢) for protection during firing.

Flames rise to the lid and exit laterally through the three flue holes; in reduction firings, glowing red reduction flames emerge. Saggers may be either perforated or solid:
・Use a solid sagger to prevent glaze blemishes and soot.
・Use a perforated sagger to allow direct charcoal flame contact for kiln effects (窯変).

Air is introduced through three lower air‑inlet holes (送風孔) using a blower, controlling combustion and atmosphere within the kiln.

2. Strengths and Weaknesses of the Raku Kiln (楽窯の長所と短所)

・Strength: Three air‑inlet holes (吸気孔) allow precise control of airflow and flame intensity. By using a traditional bellows (鞴, fuigo), one can reproduce authentic Raku firing atmospheres and effects.

・Weakness: Its extremely small size makes the kiln highly susceptible to ambient temperature fluctuations, resulting in significant firing inconsistencies and uneven heat distribution.

・Weakness: Designed for firing one piece at a time, the Raku kiln’s productivity is minimal compared to other kiln types.

・Weakness: Outcomes depend heavily on the potter’s skill; the kiln is not easy to master. Conversely, this sensitivity makes it ideal for highly skilled artisans creating singular, expressive works.