Anagama vs Noborigama: Japanese Wood Kilns Compared

The world of ceramics divides broadly into two kinds of kiln: the modern gas and electric kiln, and the wood-fired kiln handed down from antiquity. Gas and electric kilns allow precise temperature control and produce even, dependable results. Wood kilns are different. The flame moves like a living thing, ash rides the draught, and the expression of a piece shifts moment by moment inside the kiln. The pleasure of a wood kiln lies in the accidental beauty the maker never intended — and the noborigama, the climbing kiln, is its foremost example. Once the fire is lit, nobody knows the finished form until the moment the kiln is opened. That tension and mystery is the essence of wood firing.

What Is a Noborigama Climbing Kiln?

A Multi-Chamber Structure Built Into a Hillside

A Noborigama (climbing kiln) is a kiln in which several firing chambers are linked in a stepped series up a hillside. At the lowest point sits the firebox, and the flame and hot gases from the wood burned there flow in turn into the next chamber, and the next. A chimney stands at the top, so the heat travels through the whole kiln in one direction, warming it entirely.

The great advantage of this structure is fuel efficiency. The heat from wood burned in the lowest chamber is passed up like a relay, so a large volume can be held at high temperature with relatively little fuel. Because a single firing can produce a great quantity of pieces, kilns in a pottery region historically often shared a "communal kiln" and fired together.

Sizes vary widely. Most have between three and ten chambers, and some large climbing kilns exceed ten metres in overall length. The angle of the slope, the size of the chambers, the placement of the fireboxes — each region and each kiln differs subtly in design, and that difference feeds directly into the character of the ware.

Today, for reasons of safety management and fuel cost, the number of operating climbing kilns has fallen sharply. But in each region some are still maintained and used to carry on tradition and culture, and their firings draw many enthusiasts.

The History of the Climbing Kiln, Brought from Korea

The climbing kiln originated in China, appearing in the tenth century and spreading afterwards across Asia. The technology reached Japan at the end of the sixteenth and the beginning of the seventeenth century, when Korean potters who came to Japan brought advanced kiln technology to regions throughout the country.

Until then, Japanese kilns were mainly the single-chamber Anagama (tunnel kiln) or the flat kiln. The renbōshiki noborigama, the multi-chamber climbing kiln, that Korean potters introduced was a decisive innovation: by linking several firing chambers it made both mass production and high-temperature firing possible. The technique first flourished in Arita in Saga Prefecture and Hagi in Yamaguchi Prefecture in Kyushu and western Japan, then spread nationwide.

In porcelain production at Arita in particular, the climbing kiln became the foundation of industrialisation. As covered in Arita Ware: Japan's First Porcelain, 400 Years On, Arita porcelain was produced in volume during the Edo period and reached a quality and quantity sufficient for export to Europe through the Dutch East India Company. Behind that stood the efficiency of the climbing kiln.

In the older kiln regions such as Bizen, Shigaraki, and Tamba, meanwhile, the shift from the tunnel kiln to the climbing kiln proceeded at different paces. The nature of each region's clay, the style of its ware, and the temperament of its potters all influenced the choice of kiln.

How It Differs from the Anagama Tunnel Kiln

Single Chamber Versus Multiple Chambers

The anagama and the noborigama are both traditional wood-burning kilns, but their structures differ fundamentally.

The anagama is single-chambered. One long, narrow firing space — a tunnel — carries the flame from the firebox at the front toward the back. Because the structure is simple, the movement of flame and ash affects the ware directly. Temperature and atmosphere (oxidising or reducing) differ greatly between back and front, top and bottom, so where a piece is placed changes the result dramatically.

The noborigama is multi-chambered. Several firing chambers are connected, and additional wood is fed through side stoke holes set into the flank of each chamber to adjust temperature. Because temperature range and atmosphere can be varied chamber by chamber within a single kiln, different kinds of ware can be fired at the same time.

The anagama suits a single potter or a small group making distinctive work; the noborigama suits several kilns in a region firing large quantities together. Today individual artists often own an anagama, while climbing kilns are more often maintained as a region's communal kiln.

The Ware Each Kiln Suits

Because the influence of flame and ash is strong, the anagama produces rich keshiki: Shizen-yū (natural ash glaze), hiiro scarlet flashing, scorch marks. Much Bizen pottery is fired in an anagama, and a rich expression emerges without any glaze at all. Each piece has a strong individuality — ware that is truly ichigo-ichie, once in a lifetime.

The noborigama, with its large firing space and considerable freedom of temperature control, accommodates everything from porcelain to earthenware. Fine porcelain such as Arita ware and soft earthenware such as Hagi ware both have long histories of being fired in climbing kilns. Depending on the region and the maker, however, work is also made specifically to enjoy the accidental flame scenery a climbing kiln produces.

No two pieces of japanese pottery are ever the same, and meeting a piece is always ichigo-ichie. On the appeal of that kind of encounter, see the article below.

• Ichigo Ichie: Why No Two Handmade Pieces Repeat

The Wood Firing Process: From Lighting to Opening the Kiln

Loading the Kiln: Saggars and Shelves

A firing begins with kamazume, loading the kiln — the work of arranging pieces carefully inside before firing.

Pieces are not simply set on shelves. They are placed in refractory containers called saya (saggars) or arranged on tana-ita (kiln shelves) and set into the kiln. Saggars protect ware from direct contact with ash and flame. Some regions and makers, though, deliberately forgo saggars and expose pieces directly to flame and ash to produce richer keshiki. Bizen pottery is the leading example.

Loading is not merely stacking. What is placed where in the kiln determines the outcome. The potter reads the path of the flame, the distribution of temperature, and the pattern of flying ash, and positions each piece where it will fare best. Experienced potters know their kiln's habits intimately, carrying the knowledge that "a piece placed here tends to come out like this."

Loading can take several days. In a large climbing kiln it is a major undertaking, packing hundreds to thousands of pieces at once. When loading is finished, the kiln mouth is sealed with brick in preparation for firing.

From Lighting to Firing: One to Two Weeks of Management

Once loading is complete, the kiln is lit. It begins with yonetsu, preheating, warming the whole kiln slowly at low temperature. Sudden temperature change invites cracks and breakage, so the temperature is raised with care.

Once full firing begins, stoking continues day and night. Wood firing requires round-the-clock management, with potters taking shifts to watch the kiln. Reading the pyrometer, they adjust the quantity and timing of wood to control both the temperature and the atmosphere inside — oxidising or reducing.

Firing temperatures vary by ware, but roughly 1,200–1,300°C for earthenware and 1,300–1,400°C for porcelain. In a wood kiln, though, an experienced potter judges the result not from the pyrometer alone but from the colour of the flame and the state of the test pieces drawn from inside the kiln.

A kiln site at night is an extraordinary sight: the firebox glowing red in the darkness, sparks flying, the smell of smoke. Potters split wood in silence and turn back to the kiln. Thousands of years of ceramic history are concentrated in that quiet.

In a climbing kiln, firing is completed chamber by chamber from the bottom, with wood gradually added through the stoke holes of the chambers above. A single firing can take several days, and in long cases more than ten — and someone stays beside the kiln the entire time.

Opening the Kiln: Meeting What the Flame Made

When firing is complete comes the cooling. Immediately after firing the kiln interior is still above 1,000°C, and opening it in haste would break the ware through thermal shock. It is left to cool naturally until the temperature inside has fallen far enough. Cooling takes several days.

Then comes kamadashi, the unloading — the most heart-quickening moment for potters and enthusiasts alike. The sealed kiln mouth is opened and the pieces are lifted out one by one.

Each piece brings a cheer, or a quiet sigh. Pieces whose keshiki came out as intended; pieces more beautiful than anyone expected; pieces that, sadly, cracked. Inside the kiln, the maker's intention and the caprice of the flame have mixed into results nobody could predict.

When a maker says "I don't know whether the work is finished until the kiln is opened," it is no exaggeration. Wood firing is an act of collaboration between maker and flame.

The Keshiki That Flame and Ash Create

What makes wood-fired work particular is the keshiki — scenery — that no gas or electric kiln can reproduce. Keshiki is the ceramic term for the natural patterns and changes that appear on a surface during firing.

Ash Glaze and Natural Glaze

Burning wood produces a great deal of ash. Carried by the hot flame, that ash swirls through the kiln and settles on the surfaces of the ware. At high temperature it melts into glass and fuses with the clay body. This is the phenomenon called shizen-yū (natural ash glaze), or simply ash glaze.

Without the potter applying any glaze at all, the wood ash performs the role of glaze naturally. Its colour varies with the quantity and quality of the ash, the temperature, and the composition of the clay body — bluish, green, ochre, brown. Even within the same kiln, pieces set in different positions come out with entirely different expressions.

Shigaraki ware, Bizen pottery, and Iga ware are especially prized for the beauty of this natural glaze. An organic, complex expression, quite unlike the even beauty of a manufactured glaze, is among the greatest appeals of wood-fired work.

Hiiro: Scarlet Flashing

The colour of a piece differs greatly between the areas the flame strikes directly and the areas left in shadow. Flame-struck faces take on red; shaded faces can darken toward black. This contrast of light and dark is called hiiro, scarlet flashing.

Hiiro is especially beautiful in Bizen pottery, where the gradation from red to black gives the whole piece a rich expression. It is as though the history of a dialogue with the flame were inscribed directly on a single piece. Hidasuki, in which rice straw is wrapped around a piece to draw scarlet lines, applies the same principle deliberately.

Hiiro is difficult to reproduce, and creating exactly the same scenery intentionally is nearly impossible. That is precisely why each piece becomes singular, and why it carries the particular meaning of "my piece and no one else's" for the person who uses it.

Scorch and Carbonisation

Wood ash and charcoal can adhere to a piece and form black scorch patterns. And when the kiln atmosphere turns reducing, with little oxygen, the surface carbonises and blackens. This is called tanka, carbonisation.

Scorch and carbonisation may look at first like negative changes, but they give a piece depth and strength. The contrast between a black scorch mark and the clay colour of the body, and the matte black texture that carbonisation produces, are expressions a gas kiln could never create.

Yōhen: Kiln Transformation

Yōhen is the collective term for the accidental changes that unforeseen movements of flame and ash produce on a surface. It means, literally, "transformed inside the kiln."

The trace of a glaze that ran in an unexpected direction; the complex pattern made where ash piled heavily on one area alone; the shift in colour born from a fluctuation in temperature — the expressions of yōhen are endlessly varied.

In Japanese ceramics, yōhen work has long been held to carry particular value. As scenery created by nature — genuinely once in a lifetime — yōhen pieces are prized in the world of the tea ceremony as well. Yōhen is the record of a moment where a maker's skill and nature's chance crossed.

Regions That Use Climbing and Tunnel Kilns

Pottery regions across Japan continue to protect the wood-firing tradition. Each produces its own ware, drawing on local clay and local technique.

• Bizen, Okayama Prefecture　One of Japan's six ancient kilns, famous for muyū ware that uses no glaze at all. Bizen pottery is often fired in an anagama, and the long firing — one to two weeks — produces the hiiro, goma sesame speckling, and botamochi resist marks that characterise it. The deep red-brown born from the chemical reaction of iron in the clay with flame is Bizen's signature.
• Shigaraki, Shiga Prefecture　One of the six ancient kilns, known for the coarse texture of its clay and the beauty of its natural ash glaze. Both climbing and tunnel kilns are used, and the verdigris green of melted wood ash is striking. Many distinctive contemporary artists work here, and tradition and innovation coexist. → Shigaraki Ware: Why Its Clay Sparkles After 1,200 Years
• Iga, Mie Prefecture　A ceramic district near the Shiga–Mie border, sharing geology with Shigaraki, characterised by powerful forms built from coarse clay and rich natural ash glaze. Long loved by tea practitioners as a tea-ceramic region, it produces ware that embodies the aesthetic of wabi. → Iga Ware: Fire, Ash and the Beauty of Rough Clay
• Tamba, Hyogo Prefecture　One of the six ancient kilns, known as a climbing-kiln region. Tamba ware fired in a noborigama is characterised by a plain, powerful expression and rich natural glaze and hiiro. Today it is a region actively engaged in preserving and using its climbing kilns, carrying the wood-firing culture forward.
• Hagi, Yamaguchi Prefecture　The region of Hagi ware, where the technique brought by Korean potters still lives. Fired in a climbing kiln, Hagi ware is characterised by a soft white to pink surface and distinctive crazing. Praised by tea practitioners in the saying "first Raku, second Hagi, third Karatsu," it is especially renowned for tea bowls.

These regions hold firing events and kiln-opening viewings each year, offering the chance to experience wood firing directly at its source.

Where to See and Buy Wood-Fired Work

By its nature, wood-fired work rarely appears on shop shelves as mass-produced goods. It is best sought at an artist's or kiln's solo exhibition, at a region's pottery market, at a specialist gallery, or — today — online, where you can learn the story behind a piece as you choose it.

• Regional pottery markets　Bizen City holds the Bizen Ware Festival each year, where many artists and kilns sell directly. Shigaraki has its pottery market, Tamba its Tamba Ware Pottery Festival — each region holds one or two major events a year. Being able to choose a piece while talking with the maker is a particular occasion for any enthusiast.
• Galleries and specialist shops　Major cities such as Tokyo, Kyoto, and Osaka have galleries dealing specifically in wood-fired work. Pieces selected by experienced buyers are on display, and you can meet one-of-a-kind work of assured quality.
• Online platforms　In recent years, platforms for buying japanese pottery online have grown considerably. Nokaze carries work by artists from Bizen, Shigaraki, Iga, Hagi and other regions, letting you choose a piece alongside the story of its region and its maker. For anyone living far away, or without easy access to a specialist shop, online is an important entrance to wood-fired ware.

Primal Flame, and the Finest One-of-a-Kind Work of Our Time

The noborigama is a multi-chamber wood kiln built into a hillside, and a distillation of the technology that has sustained Japanese ceramic culture. Technique brought by Korean potters fused with each region's clay, climate, and the sensibility of its craftspeople, producing ware of distinct character in Bizen, Shigaraki, Iga, Tamba, and Hagi.

The appeal of wood firing lies above all in accidental beauty: the natural glaze that melted ash creates, the hiiro the flame draws, the depth of black from carbonisation, and the unforeseen yōhen. However far a potter refines their skill, the movement of flame cannot be fully controlled. The essence of wood firing lies precisely in that uncertainty.

Modern gas and electric kilns produce even quality dependably — and yet there are expressions only a wood kiln can make. The people who know this still travel to the regions in search of wood-fired work, queue at pottery markets, and stand a long while in galleries looking at pieces.

When you pick up a piece, the flame scenery inscribed on its surface is the record of many days of firing. It is the crystallisation of a singular moment, born on the morning of a kiln opening finally reached after a potter split wood and watched through the nights.

To place a wood-fired piece on your daily table is to become part of that long story yourself. With every use, the scenery the flame made changes a little, settling into the hand of the person who uses it. That pleasure of growing a piece is another of the particular values wood-fired ware carries.

The finest one-of-a-kind work of our time, made by primal flame and ash. That is wood-fired ware, and the ware of the climbing kiln. Do welcome one to your table.

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