How about cracks or pinholes in the inner glaze?

How about cracks or pinholes in the inner glaze?

When assessing Jian Zhan chawan / teabowl, especially those made in the traditional style, certain characteristics are not necessarily flaws but inherent traits of the craft, while others are genuine defects. Understanding the difference is key to both safety and appreciation.

Here’s a breakdown of potential issues, categorized by whether they are typical/acceptable or problematic.

Inherent Characteristics (Usually NOT Defects)

These are often celebrated as part of the "one-of-a-kind" beauty of Jian Zhan, resulting from the high-temperature (over 1300°C), reduction-fired process.

  1. Pinholes / Pinpricks:

    • What they are: Tiny holes in the glaze surface. They are caused by air bubbles escaping from the clay body during firing, bursting through the glaze.

    • Impact: In traditional, thick-glazed Jian Zhan, small, scattered pinholes are very common and generally acceptable. They are considered part of the "breathing" texture of the ware. They do not typically compromise structural integrity or hygiene for tea use.

  2. Crazing:

    • What it is: A fine network of hairline cracks in the glaze. It occurs due to the different cooling rates (thermal contraction) of the glaze and the clay body.

    • Impact: In many ceramic traditions, crazing is considered a defect. However, in some Jian Zhan styles, subtle crazing is tolerated or even appreciated as it can enhance the patina over time. It is not a safety issue, but the cracks can stain with tea, changing the cup's appearance.

  3. Glaze Roll-off / Uneven Rim ("Glaze Tears"):

    • What it is: The thick glaze flows downward during firing, often leaving the rim partially unglazed or thinly glazed, revealing the dark clay body.

    • Impact: This is a defining and desired characteristic of many Jian Zhan cups. The unglazed rim is usually smooth and fired to a glass-like state. It is not a defect and poses no safety risk.

Final Advice: Appreciate the natural, rugged beauty of inherent traits like subtle pinholes and glaze flow, but be vigilant for genuine structural and safety defects like body cracks and glaze peeling.