Buff clay
Start with the pale ground colour and the contrast of any darker grains. “Buff with dark specks” is a useful description; duanni is a material name that needs further evidence. The schematic below helps describe colour, but neither its yellow tone nor its dots is a diagnostic test.
On this page
How the surface is made
The sources use related names differently. The 1994 technique manual describes Tuanshan clay as purple and green clays occurring together. Yingge’s 2018 account describes tuanni as a mixture of multiple ores. Natural association and deliberate blending are different histories; a pale fired surface cannot decide between them. Ask how the maker uses the name for this batch.
What the measurements establish
No identified duanni test body with a verified method supports a universal composition or firing range on this page. The former oxide percentages and firing interval came from a general news feature. They have been removed as material specifications. A dark speck alone also cannot establish underfiring: that needs evidence about the body and firing.
What to ask next
Describe the colour, sheen and visible grains separately. Then ask for the clay supplier or batch record, preparation and firing record, and any surface treatment. Composition needs a named, tested sample; a photograph cannot supply it.
Standards#
| Standard | Clause | What it covers | Sources |
|---|---|---|---|
| GB/T 10816-2024 紫砂陶器 | record | Recommended national standard for zisha ware, issued 2024-12-31, in force 2025-07-01, replacing GB/T 10816-2008. | 3 |
| GB/T 10816-2024 紫砂陶器 | 1 (scope); foreword | Scope speaks of a fine-textured, iron-rich special clay and covers classification, technical requirements, inspection and labelling of products. The foreword says the 2008 lead and cadmium release requirements were removed from this edition. Read through a commercial English rendering of the front matter only; clauses 5 onward were not seen. | 4 |
Sources#
- 陶博館季刊 2018/1–3月：宜興紫砂（紫砂泥特色） ↗
- 紫砂泥料之什么是段泥 ↗
- GB/T 10816-2024 紫砂陶器 (Zisha ware), standard record ↗
- GB/T 10816-2024 English (scope and changes) ↗
- 王建中、范建军、唐伯年：《紫砂壶制作技法》。北京工艺美术出版社，1994。15–18 · PDF 23–26。
Status and editorial notes draft
Sources are listed below. Their presence does not certify every claim; source-specific interpretations and unresolved questions are identified in the text. This page has not received independent expert approval.
Exact supporting passages for the quantitative material claims and historical attributions still require checking against the cited publications.