The Art of Ceramics: Exploring its History and Forms

Ceramics have played a vital role in human civilization, from early pottery to exquisite porcelain. This article delves into its definitions, classifications, and key types, including earthenware, stoneware, and porcelain.

Table of Contents

• 1. What is Ceramics?
• 2. Ceramics in a Narrow Sense
• 3. Ceramics in a Broad Sense
• 4. Earthenware (Doki, 土器)
• 5. Stoneware (Sekki, 炻器)
• 6. Pottery (Tōki, 陶器)
• 7. Porcelain (Jiki, 磁器)

1. What is Ceramics?

In simple terms, ceramics refer to objects made by shaping and firing raw materials such as clay or stone.
More specifically, ceramics are created by forming natural clay, commercially available clay, or crushed raw materials called tōseki (陶石, pottery stone). These shaped objects are then coated with yūyaku (釉薬, glaze), a glass-like material, and fired to complete the process.

2. Ceramics in a Narrow Sense

The term ceramics (陶磁器, tōjiki), in a narrow sense, refers to pottery (陶器, tōki) and porcelain (磁器, jiki). Pottery includes relatively thick items such as tea cups, while porcelain includes thinner items like coffee cups with handles.

The reason many porcelain items have handles is that porcelain is thinner and has a denser body than pottery, making it more heat-conductive. All ceramic materials have microscopic gaps in their structure. If these gaps are large, air can enter, reducing heat transfer. Conversely, if the gaps are small, the insulating air cannot penetrate.

Since porcelain has very few gaps in its structure, it heats up quickly when filled with a hot liquid but also cools down rapidly. Pottery, on the other hand, has larger gaps that allow air to enter, forming an insulating layer that slows down heat transfer. As a result, pottery warms up slowly but retains heat longer.

3. Ceramics in a Broad Sense

In a broader sense, ceramics (陶磁器, tōjiki) is a collective term that includes earthenware (土器, doki), pottery (陶器, tōki), stoneware (炻器, sekki), and porcelain (磁器, jiki).
The history of Japanese ceramics begins with earthenware from the Jōmon (縄文) and Yayoi (弥生) periods, which later evolved into stoneware and pottery during the Kofun (古墳) and Asuka (飛鳥) periods. Japanese porcelain production is believed to have started in the 17th century in Arita (有田, present-day Saga Prefecture).

4. Earthenware (Doki, 土器)

Earthenware refers to unglazed, low-fired ceramics such as Jōmon and Yayoi pottery, fired at temperatures of 500–800°C. In ancient times, kilns did not exist, so pottery was fired using a method called "open firing" (野焼き, nobiyaki), where pieces were stacked in an open area and burned with wood and other combustible materials.

It is believed that ancient people discovered by chance that clay hardens when heated. Looking at excavated pottery and artifacts, we can see that the basic shapes of modern ceramic vessels were already established during the Jōmon and Yayoi periods.

After the Yayoi period, low-fired earthenware became known as hajiki (土師器). During the medieval period, hajiki was also called "kawarake" (かわらけ) and was considered sacred. Even today, the kawarake-nage (かわらけ投げ) ritual, in which earthen cups are thrown from a high place for good luck, continues in Japan.

Because earthenware is fired at low temperatures, it is not fully vitrified, making it more fragile and porous than high-fired ceramics. It absorbs water easily and dries quickly.

Example of Earthenware: Unglazed Flower Pots A familiar example is the terracotta flower pot, which is typically brown, has moderate strength, and allows for good water drainage—ideal for growing plants. Even today, earthenware is produced for specific practical purposes.

5. Stoneware (Sekki, 炻器)

Stoneware is a lesser-known category of ceramics, referring to unglazed ceramics that are high-fired at 1,000–1,200°C. Since it is fired at high temperatures without glaze, it is also called "unglazed vitrified pottery" (無釉焼き締め陶, muyū-yakishime-tō).
Because it is fired at medium-to-high temperatures, stoneware is more vitrified than earthenware, making it more durable and waterproof.

Example of Stoneware: Bizen Ware (備前焼) A well-known example of stoneware is Bizen ware, which is fired without glaze, allowing the natural texture of the clay to remain visible.
The transition from earthenware to stoneware occurred in the 5th century, when new ceramic technologies were introduced from the Korean Peninsula. These included: The Potter’s Wheel (ロクロ, Rokuro) – A spinning platform that allows clay to be shaped more efficiently.
The Anagama Kiln (穴窯, Anagama) – A simple underground kiln that enabled more controlled, high-temperature firing compared to open firing.

With these innovations, Japan began producing a new category of high-fired ceramics known as Sue ware (須恵器, Sueki), which laid the foundation for later stoneware production.

6. Pottery (Tōki, 陶器)

Pottery is made from clay and is high-fired at 1,000–1,200°C with a glaze coating.

Example of Pottery: Madara Karatsu (斑唐津) Unlike the pure white body of porcelain, the clay body of pottery varies in color, appearing brown, reddish, or dark depending on the firing method.
From the medieval period onward, glazes were intentionally applied to pottery. In Seto kilns (瀬戸窯, present-day Aichi Prefecture), for example, wood ash and locally sourced feldspar were crushed and mixed with water to create glazes.

The introduction of glazes and improved kiln technology led to the widespread production of glazed pottery. During the Muromachi period, semi-aboveground kilns (大窯, Ōgama) improved fuel efficiency, and by the Edo period, multi-chamber climbing kilns (登窯, Noborigama) enabled mass production.

Today, electric and gas kilns allow for even more controlled firing conditions, and various glazes are used to create colorful and diverse pottery.

7. Porcelain (Jiki, 磁器)

Porcelain is made from crushed pottery stone (陶石, Tōseki), which is more heat-resistant and denser than clay, requiring high firing temperatures of 1,200–1,300°C.

Since porcelain clay naturally fires to a white color, transparent glazes are often used to highlight its brightness.

Example of Porcelain: White Porcelain (白磁, Hakuji) Porcelain is non-absorbent (nearly 0%) and more durable than pottery. When tapped, it produces a high-pitched sound ("ping, ping"), unlike the dull sound of pottery. It also exhibits translucency (透光性, tōkōsei), meaning thin porcelain pieces allow light to pass through.

Japan’s porcelain industry began in the 17th century in Arita (有田, present-day Saga Prefecture), where high-quality pottery stone was abundant. Arita porcelain, with its blue-and-white decoration (染付, Sometsuke), became widely popular and was exported internationally.

Before the Edo period, Japan lacked the means to produce porcelain because high-temperature kilns like the climbing kiln (登窯, Noborigama) were not yet available. These advanced kilns, introduced from Korea, allowed Japan to produce porcelain efficiently.
Porcelain production later spread to regions such as Kutani, Tobe, Kyoto, and Seto, establishing Japan as a significant player in global ceramics.