How can I identify genuine tenmoku chawan glaze patterns?

Identifying genuine Tenmoku Chawan glaze patterns requires a combination of knowledge, careful observation, and sometimes a bit of healthy skepticism. True Jian ware from the Song Dynasty is extremely rare and mostly found in museums or top-tier auctions. What you'll more commonly encounter are later Japanese, contemporary Chinese, or studio potter interpretations.

Here is a detailed guide to help you identify genuine patterns and distinguish them from modern interpretations.

Core Principles First

1. Context is King: The first question is always, "What is the object's claimed origin?"

   • Song Dynasty Jian Ware (circa 960-1279 AD): The holy grail. Truly authentic pieces are characterized by a heavy, coarse, dark stoneware body (often gray or brown), a thick glaze that pools and stops short of the foot, and a cut or unglazed foot rim that shows the firing clay. They are almost exclusively simple bowl forms (chawan for tea).

   • Japanese Tenmoku (from ~13th-16th century): Brought from China by Buddhist monks and later made in Japan (e.g., Seto ware). They often have a more refined body and sharper potting. The patterns are intentional homages.

   • Contemporary / Studio Pottery: From the 20th century onward. These celebrate the aesthetic but are not antiquities. The clay is often different, the foot rim treatment varies, and there may be artist signatures.

2. The Glaze is a Record of the Fire: Genuine antique patterns are the result of natural iron-oxide crystallization in a wood-fired reduction kiln. They are not painted on. This results in randomness, depth, and subtlety that are very hard to perfectly replicate.

Identifying Key Patterns

1. Yōhen (曜變) - "Radiant" or "Multicolor"

• Genuine Antique: The rarest and most prized. The hallmark is a blue-purple iridescent sheen that seems to float above a dark, almost black glaze. This iridescence forms a halo around the larger oil spots. The pattern is incredibly complex, deep, and seems to change with the light. There are only 3-4 complete bowls in the world recognized as true Song Dynasty Yōhen, all in Japan.

• Modern Imitations: Often achieved with metallic salts or overglaze applications. They can look garish, with a uniform "rainbow" effect that sits on the surface, lacking the profound depth and the specific halo-effect around spots.

2. Yuteki (油滴) - "Oil Spots"

• Genuine Antique: The spots are crystalline spheres of iron oxide that floated to the surface. In the best pieces, they are silvery and metallic, with a three-dimensional quality. They vary in size and density, often being more concentrated near the rim where the glaze is thinner. They are embedded within the glaze, not on top. Under magnification, they show a distinct crystal structure.

• Modern Versions: Can be convincing, but often look too perfect or uniform. The spots may appear flat, painted, or stamped. Some are created with a heavy application of iron oxide slurry, which can look thick and crusty rather than integrated.

3. Kage (禾の目) / Hare's Fur (兔毫)

• Genuine Antique: Streaks radiate from the rim down toward the base. They are caused by glaze flow. The streaks should have a silvery, golden, or blueish tinge and appear to lie beneath a clear top layer of glaze. They are delicate, directional, and show natural variation—some areas may be dense, others sparse.

• Modern Versions: Often applied with a brush or trailed slip, resulting in streaks that look too linear, uniform, and sit on the surface. The color can be harsh (bright yellow or rust) rather than subtle.

4. Partridge-Feather (鷓鴣斑)

• Genuine Antique: This is a sub-type of oil spots, but with a key difference: the spots are larger, more irregular, and often have a distinct "eye" or central point of a different color (like a bird's feather). The background glaze is typically a lighter buff or brownish tone, providing contrast. The effect is mottled and organic.

• Modern Versions: Often confused with simple oil spots. True partridge-feather is rare even in good reproductions. Modern versions might use a two-tone glaze application or decals that look unnaturally patterned.

A Step-by-Step Examination Guide

1. Look at the Form and Body:

   • Turn the piece over. Examine the foot rim. Is it unglazed? Is the exposed clay body coarse, fine, modern-looking? Is the foot neatly cut or uneven? (Song pieces often have an uneven, hand-cut foot).

   • Feel the weight. Song Dynasty bowls are often surprisingly heavy and thick for their size.

2. Examine the Glaze Surface:

   • Texture: Run your finger (gently!) over the pattern. True crystallization is often slightly textured or subsurface. Painted-on effects are usually smooth or raised in a different way.

   • Pooling: The glaze should thickly pool at the bottom, often becoming opaque or a different color (deep blue or dark brown). The transition is gradual.

   • Crazing: Antique pieces will have very fine, aged crackle (crazing). The cracks will be stained with time (tea, dirt). New crazing looks white and clean.

3. Analyze the Pattern Itself:

   • Depth: Use a strong, raking light. Do the patterns shine from within, or do they reflect light from the surface?

   • Randomness: Are the oil spots all the same size and perfectly spaced? Nature isn't perfect. Look for natural clustering and size variation.

   • Color Subtlety: Are the colors metallic and subtle, or are they bright and paint-like?

4. Consider the Overall "Feel":

   • Genuine Song Dynasty Jian ware has an aura of unassuming power, profundity, and natural accident. It is humble yet majestic. Many modern pieces, even beautiful ones, can feel more "designed" or intentionally decorative.

Red Flags

• A perfect, shiny, glass-like glaze. Tenmoku glazes are more complex.

• A perfectly white, refined porcelain body. True Jian ware is stoneware.

• A pattern that looks exactly the same on the inside and outside. This is almost always a modern, sprayed-on effect.

• A price that seems too good to be true. A genuine Song bowl is a seven-figure object.

Final Advice

• Study the Masters: Look at high-resolution photos of accepted museum pieces (Tokyo National Museum, Fujian Museum, British Museum, etc.).

• Handle Reproductions: Visit galleries that sell high-end contemporary Tenmoku-style work. Feeling a good modern piece will help you understand the glaze.

• Consult an Expert: If you are considering a significant purchase of an antique, always get it authenticated by a recognized expert in Chinese ceramics, preferably from a major auction house (Sotheby's, Christie's) or museum. The market is filled with sophisticated fakes.

In short, genuine Tenmoku patterns are a marriage of controlled technique and natural chaos from the kiln. They have a depth, subtlety, and randomness that is the primary clue to their authenticity.