April 15, 2004


Efficient Use of Energy For 1000 Years: Tokoname-yaki Pottery

* This article is under copyright protection.

Manabu Akaike
Universal Design Intelligence Inc.

From a City of Drainpipes to a City of Tiles

Production of earthenware pottery in our nation is said to have begun in the 5th century. After five hundred years, bowls and plates with glazes on the surface were being made. In Japan, there are six ancient kiln sites in towns now famous for their pottery, which has become synonymous with the location. They are Seto, Shigaraki, Echizen, Tanba, Bizen and Tokoname. The Tokoname-yaki made in Aichi Prefecture can boast of being the oldest of these ancient wares, as well as the largest in scale. In the 12th century, Tokoname potters made religious articles such as urns for storing Buddhist sutra scrolls but from the 15th century on, jars and pots for household use made up the majority of the output.

There are several reasons behind the great support enjoyed by so-called Old Tokoname ware made during this period. One is the high quality clay of the Tokoname region, and another is the unique emerald sheen of the Tokoname-ware, the beauty of the natural green ash glaze on the shoulders of the jars and pots. This natural glaze was formed by the ashes of the firewood that was burned to fuel the kiln. In other words, efficient use of waste materials brought "added value'' to the product.

The region also used the slope of its hills to develop an efficient way of using energy. Ancient kilns used up till the Edo period were generally the anagama style single chamber wood-fired "cave kiln," or the ohgama "great kiln," a larger version of the anagama, both of which were dug into the side of a hill. These evolved into the noborigama which were tall, multi-chambered kilns that climbed up the side of the hill. Careful scrutiny of different types of fuel that would provide the highest firing temperatures also took place over time, with high-resin long-burning red pine being the firewood of choice. In the Meiji era, research into coal-fired kilns brought from Europe was undertaken, and the square down-draft style coal-fired kiln that is generally known as the Setogama or "Seto kiln" was developed. With the appearance of this kiln, potters were able to save as much as 50% on fuel costs compared to red pine, so these kilns were in continuous use until after the second World War.

Special mention should be made of the efficient use of broken and worn-out bits of pottery. When walking through Tokoname City one can view beautiful ''walls of pottery'' everywhere.

Recently Tokoname with its long history of efficient use of energy and resources has been reborn as ''tile city,'' where ceramic tiles for building materials are created. This area has also been home to a well-known power brand, namely INAX, which was renamed from Ina Ceramics.

Zero Emissions in Historical Tokoname Ware

INAX is well-known for the television commercial for its antibacterial toilet. Together with its bathroom fixtures and other residential space businesses, it also manufactures and supplies a large number of superior ceramic building materials. One of them is a new material called Soil Ceramics that won an Ecology Design Prize from MITI in 1997. Today, many companies are forging ahead with research and development of so-called ''zero emissions" policies, seeking to reduce industrial and manufacturing waste to zero. The Soil Ceramics developed by INAX is a worthy representative of the successful fruit of such a quest.

Ceramics are made by using energy to fire processed natural earth to create products like tiles or toilets. INAX tried to find how it could reduce its consumption of the two main input components of this production system, namely "materials" and ''energy," creating a closed production system. To sum up, with ceramics, the careful removal of just a tiny bit of the impurities in its material will result in a product that is three or four times stronger. If strength is quadrupled, the thickness can be halved. Consumption of raw material is reduced by half, and transfer and handling of materials as well as energy consumption can also be reduced across the board.

The Soil Ceramics developed by INAX uses earth itself as the raw material. The soil is passed through an impurities removal process, and then formed through immersion in high pressure steam that is the by-product of the ceramics factory. Since it is not fired, the use of fuel is very low compared to ordinary fired ceramics. The amount of energy consumed in production is half that of manufacturing cement and less than one-fifth that of ordinary pottery or ceramics. The amount of carbon dioxide emissions that are harmful to our earth's atmosphere is one-quarter that of cement manufacture and less than half that of ordinary ceramics.

For the soil to be used as the raw material, excess fill from building sites or scrap left over from other production processes can be used, and local specialties like earth or rope, or seashells, can be incorporated into the mix. Goods made this way can be returned to the earth after use without polluting the soil, perhaps to be recycled again as raw material for another batch of Soil Ceramics.

JAPAN CLOSE-UP, August 2002, published by PHP

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