Though only developed in the late 1800s, the unglazed brick-red kyusu has become synonymous with Tokoname-yaki. Despite this, this ancient pottery town in Aichi Prefecture boasts a rich variety of clays, designs, and finishes used to make its famous teaware. Here are some of the most popular:

Tokoname Clay Types

Perhaps the most important factor in deciding teaware's final feel, functionality, and appearance is the clay from which it is made. As the majority of Tokoname ware is unglazed, the clay itself determines the final finish of the piece. 

 

Shudei (朱泥 - vermilion clay)

This iconic fine-grained clay of Tokoname ranges from a bright scarlet to a softer orange red. Originally, Tokoname Shudei was made from the soil that once lay at the bed of the prehistoric Lake Tokai. Now called honshudei (本朱泥 - real/true shudei), this original clay was praised for its positive effects on the taste of tea and was used to make domestic teapots in imitation of Chinese Yixing ware in the 19th century. Nowadays, honshudei has become rare and many potters use more modern formulations that approximate its taste and colour. Shudei’s iconic hues come from its relatively high iron content. When fired in an oxidising atmosphere (also called ‘firing in oxidation’, i.e. there is enough oxygen supply to allow complete combustion, turning the fuel into water and carbon monoxide), the iron compounds oxidise and turn a bright red-orange.

 

Kokudei (黒泥 - black clay)

Generally speaking, there are two types of kokudei. The first is simply clay that has been dyed black, while the other is actually shudei, but fired in reduction. Unlike an oxidising atmosphere, a reducing atmosphere has limited oxygen, meaning there is only incomplete combustion, producing carbon monoxide (CO) instead of carbon dioxide (CO₂). This unstable CO reacts with oxygen-containing iron compounds in the clay to form CO₂, thereby reducing these compounds (removing oxygen from them) and changing their colour, usually to a dark brown or black. Additionally, reduction firing can produce a lot of soot and smoke which adds to the darkening of the clay.

 

Ryokudei (緑泥 - green clay)

This striking green clay gets its colour from added cobalt, which turns the clay green when fired in oxidation. Ryokudei clays can vary greatly in hue and saturation, ranging from deep forest greens to subtle green-greys. 

 

Koudei (黄泥 - yellow clay)

A less common clay, koudei is stained anywhere from a soft ivory to a vibrant yellow.

 

Nerikomi (練り込み - kneading)

Nerikomi is not technically a type a clay but rather a technique in which various coloured clays are kneaded together to form beautiful marbling patterns that resemble agate. Sometimes just two colours are used to produce bolder spiralled designs, while other times up to 4 or 5 clays are used to produces a more intricate effect. This technique is often accented with cuts made into the surface of the vessel, revealing the layers of patterns and marbling. 

 

Yakishime (焼締 - rough unglazed stoneware)

This relatively unprocessed clay has a coarser texture when compared to the fine-grained shudei, giving the finished pieces a rougher surface. Like most Tokoname clays, yakishime is fired without a glaze, which showcases it unique texture. Yakishime is often wood-fired, which can produce various kiln effects. 

 

Finishes and Decorations

Apart from the engraving, inlay, and painting techniques that are common in many Japanese ceramic production regions, Tokoname has a few that are unique and seldom found elsewhere.

 

Tochiri (トチリ)

This pattern of fine diagonal lines is made by scraping the surface with a razor blade while the piece is spinning on the wheel.

Youhen (窯変 - kiln change)

Youhen is used to generally describe many kiln effects across various ceramics styles (including Tenmoku, where it is spelled 曜変). In Tokoname-ware, however, this term specifically refers to the attractive and often dramatic colour gradients and patches caused by certain firing conditions. One way this is achieved is by partially submerging the teapot in sawdust while firing. Youhen pots typically have a gradient from a dark black or brown to shudei red, though some potters use this technique with ryokudei or koudei clays to produce unique colour patterns. As the exact pattern produced is highly dependent on the position of the piece in the kiln as well as the firing temperature, atmosphere, and fuel, producing a consistent result across many pieces takes a great amount of skill, patience, and practice. 

Ceramics artists are always developing new decoration techniques or adapting old ones to new genres, so check back to learn about more Tokoname-yaki finishes like mogake, hidasuki, and kushime!

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