【Japanese Pottery】Various types of glaze. Sōyū (総釉, sōgusuri) and Meato (目跡, meato) | Exposed Clay (土見せ, tsuchimise)

Table of Contents

• 1. About Sōyū (総釉, sōgusuri)
• 2. What is Meato (目跡, meato)?
• 3. What is Tsuchimise (土見せ, Exposed Clay)?

1.About Sōyū (総釉, sōgusuri)

Sōyū refers to a glaze that is applied to the entire surface of a ceramic piece. The word "sō" (総) means "all" or "entire," and "yū" (釉) refers to glaze. Works with sōyū have glaze applied even to the inside of the footring (kōdai, 高台).

In these pieces, the glaze is carefully applied so that even the area where the piece contacts the kiln shelf (called "tatamitsuki, 畳付き") is glazed, leaving minimal exposed clay. One example of this practice can be seen in ancient Chinese celadon (青磁, seiji), which was made to resemble highly prized jade objects (玉器, gyokki).

In Japan, raku tea bowls (楽茶碗, rakuchawan), which began in the Momoyama period, were also often fully glazed. The black or red glaze symbolized beauty, and applying it over the entire surface of the bowl was seen as an aesthetic choice. However, producing sōyū pieces is more labor-intensive.

Because glaze melts into glass at high temperatures, it can cause the piece to stick to the kiln shelf. To prevent this, a small clay piece is placed under the footring to raise the piece, which results in visible marks called "meato" (目跡).

2. What is Meato (目跡, meato)?

Meato are traces left by small clay pieces used to keep ceramic works from sticking to the kiln floor during firing. These spacers act as buffers, preventing the glaze from fusing the piece to the kiln surface.

The small round clay pieces placed underneath the ceramic body are called "me" (目), while the base plate they rest on is called "tochi" (トチ) or "hama" (ハマ). Because it looks like a rice cracker, it's sometimes also called "senbei" (センベイ).

If you look closely at the "me," you may see traces of white glaze—possibly remnants of feldspar-based glazes like shino glaze (志野釉, shinoyū). Stacking pieces this way is known as "me-zumi" (目積み), and the materials used for "me" vary depending on the method:

・Taidome-zumi (胎土目積み): Uses the same body clay (胎土, taido) as the piece, ensuring matching firing characteristics and shrinkage rates.
・Suname-zumi (砂目積み): Uses small balls of sand instead of clay. After firing, the sand crumbles easily, making it simple to remove.
・Tōsekime-zumi (陶石目積み): Uses porcelain stone (陶石, tōseki), typically with porcelain works.
・Kaime-zumi (貝目積み): Uses high-heat-resistant seashells such as akagai (赤貝). This often leaves interesting shell imprints on the base.

Let me know if you'd like the next part翻訳ed now or if you'd like to adjust anything!Advantages of Taido Mezumi (胎土目積み)

Using taido mezumi, where the support pieces are made from the same clay body (胎土, taido) as the work itself, offers several practical benefits. Since the fire resistance and shrinkage rate are identical, it prevents issues such as the main piece surviving the firing while the supporting clay (the "me") is destroyed by heat. Because it uses part of the same clay body, preparation is easy and low-effort.

Other Types of Mezumi (目積み)

・Suna mezumi (砂目積み) uses small balls of sand left over from clay refinement. While easier to remove than taido mezumi, the crushed sand can scatter and negatively affect the appearance of the piece.
・In some cases, rice husks are used in place of sand.
・Tōseki mezumi (陶石目積み) is often seen in kilns for porcelain such as those in Arita. Since it uses porcelain stone (陶石, tōseki), the base material for porcelain, it can be considered the porcelain version of taido mezumi.
・Kai mezumi (貝目積み) uses small bivalve shells, such as akagai (赤貝), which leave decorative striped patterns. Only small-sized shells—around the size of a shijimi clam—are used.

Decorative Effects of Kai Mezumi (貝目積み)

Shells are placed beneath the ceramic piece during firing, leaving decorative marks after firing. The photo below shows an example of meato (目跡) created by akagai shells.

These shell marks can become a striking visual element. In addition to the footring (tatamitsuki, 畳付き), they may also appear inside the bowl. Meato are often seen on glazed ceramics but can also be found on pieces with exposed clay (土見せ, tsuchimise), serving both a practical and decorative role.

3.What is Tsuchimise (土見せ, Exposed Clay)?

Tsuchimise refers to parts of a glazed ceramic piece that are left unglazed. For example, in a glazed teabowl (chawan, 茶碗) or sake cup (guinomi, ぐい呑み), the foot and surrounding area may be left unglazed, revealing the clay body.

This allows appreciation of the natural texture and coloration of the clay (胎土, taido), which is obscured in fully glazed (sōyū, 総釉) works. For this reason, tsuchimise is also referred to as "rotai" (露胎), meaning "exposed body."

An additional advantage is that unglazed surfaces are less likely to stick during firing. However, while less prone to adhesion than glaze, rotai pieces can still fuse to the kiln shelf. For this reason, some tsuchimise pieces also show meato.

Terms like sōyū (総釉) and tsuchimise (土見せ／露胎) are commonly used in describing bowl-shaped works such as tea bowls. These terms usually refer to the foot or the area around the footring. We hope this information aids in appreciating and selecting such works.