Yingjing Sandware

Yingjing Sandware

Yingjing Sandware is a protected geographical indication product.

　　Celebrated for its unique raw materials, special production techniques, distinctive design, and outstanding performance, "Yingjing Sandware" has a history spanning more than 2,000 years. With its classic and elegant shapes, unique glaze colors, and properties such as high-temperature resistance, corrosion resistance, non-oxidation, no discoloration, and no chemical reactions with acids, alkalis, or salts in food during cooking, it helps preserve food for extended periods without spoilage and is harmless to humans. It serves as an ideal tableware item and also functions as a piece of folk art. It has won two gold awards and two product awards in Sichuan Province.

　　Yingjing Sandware is made from locally sourced ancient city clay, which is dried, ground, and mixed with fine coal cinder to form a clay body. After being fired at high temperatures and coated with a glazed surface layer, it is cooled to completion. The final product features a classic and elegant shape, a bright silver finish, high-temperature resistance, no deformation, long-term durability, ease of use, and low cost. It has a wide range of uses — suitable for cooking, brewing tea, holding water, or storing grains. When used to contain cooked food, it can keep the contents fresh and flavorful even after twelve hours in summer or autumn. Due to its slow heat conduction and dissipation, it helps retain nutrients and freshness when stewing meat or cooking vegetables. For instance, when used to braise meat over a low flame, the meat becomes tender and the broth remains richly flavored, offering a unique taste. The traditional dish “Clay Pot Fish Head” specifically requires the use of a “Yingjing Clay Pot.” Currently, there are over forty varieties sold across the province. The product has been exhibited at the Beijing Arts and Crafts Exhibition, the Canton Fair, and the Philadelphia Arts and Crafts Exhibition in the United States, receiving widespread praise and popularity from both domestic and international visitors.

　　Yingjing Sandware — Administrative regions under the jurisdiction of six towns in Yingjing County, Sichuan Province: Yandao Town, Huatan Town, Liuhe Township, WuXian Township, Lietai Township, and Minjian Township. "Proposal Letter on Delimiting the Protected Production Area Scope of Yingjing Sandware as a Geographical Indication Product" by the People's Government of Yingjing County, Document No. Ying Fu Han [2012] 64. Local Standard of Yingjing County, Ya'an City: DB511822/T001-2004 "Yingjing Sandware."

　　Quality and Technical Requirements for Yingjing Sandware

　　I. Product Categories

　　Daily-use products, arts and crafts products.

　　II. Main Raw Materials

　　1. White Fine Clay: A unique clay found in Yingjing County, with iron content between 2% and 6%, appearing yellowish-white, fine-textured, and highly adhesive. The ore type is weathered residual clay, showing a microscopic flaky clayey structure with a soil-like formation.

　　2. Dulan Carbon Second-Class Coal: Coal cinder produced after burning Dulan Carbon (which is jet-black, glossy, and forms independent blocks).

　　III. Processing Techniques

　　1. Clay Material Processing Workflow: Raw material extraction → weathering → sorting → crushing → drying.

　　2. Yingjing Sandware Production Workflow:

　　(1) Ingredient mixing → ball milling → sieving → aging → slip casting (slurry) → drying the mold → decoration → polishing → firing → glaze removal → inspection → packaging.

　　(2) Ingredient mixing → ball milling → sieving → aging → vacuum refining of clay → manual or mechanical forming → drying the mold → decoration → polishing → firing → glaze removal → inspection → packaging.

　　3. Technical Requirements for the Process:

　　(1) Clay Preparation: Use locally sourced white fine clay stored outdoors, subjected to weathering, leaching, and sun drying. Mix it with Dulan Carbon second-class coal in proportion, then add water and process through ball milling, sieving, aging, stirring, and darkroom aging for 15 days. The resulting slurry is used for slip casting, while clay for manual or mechanical forming undergoes additional vacuum refining and aging. Clay fineness is selected based on product needs, with sieve residues ≤1% through 80, 100, 150, 200, or 250 mesh sieves; plasticity index of the clay ≥2.5.

　　(2) Forming: Hand-forming, mechanical forming, or slip casting.

　　(3) Mold Drying: After forming, dry the molds in a cool, ventilated place at 8°C to 25°C, avoiding direct sunlight.

　　(4) Decoration: Primarily done through carving.

　　(5) Polishing and Finishing: Coarsely grind the rough surface of the dried mold, then perform fine grinding with amber rods or ox horn slices, followed by precision polishing.

　　(6) Firing: Place the finely polished dried molds in a mantou (steamed bun) kiln heated to 1,200°C to 1,300°C. Control the heating curve, firing temperature, and firing atmosphere during the firing process, focusing on combining three firing techniques: slow firing, steady firing, and fast firing.

　　(7) Glaze Removal: Once the piece is fully fired, lift it with a long rod fitted with an iron hook into a reduction pit (commonly known as a smoke-firing kiln or glaze-removal pit), add cedar branches or pine sawdust, and quickly seal the pit. This allows the high-temperature piece to undergo “smoldering” with the added material. Through this smoldering process, a series of physical and chemical reactions occur. Under high temperatures, the oxide layer on the surface of the piece is forcibly reduced before the ware is allowed to cool naturally.

　　(8) Unloading and Inspection: Once cooled naturally, the finished products are removed from the kiln, inspected, and classified and stored according to quality grades.

　　IV. Quality Characteristics

　　1. Appearance and Quality Features:

　　(1) Daily-use Products: Yingjing Sandware features classic, elegant, and practical designs, with exquisitely carved patterns that do not oxidize or fade. The products are solid in texture, contain fine pores, produce a resonant sound when struck, and display a soft iron-gray metallic luster on the surface.

　　(2) Arts and crafts category: Time-honored in style, with solid texture, a crisp ringing sound when struck, and a smooth, soft luster. Decorations are exquisitely carved.

　　2. Physicochemical indicators:

　　(1) Daily-use products category:

　　① Thermal stability: No cracking after one thermal shock test from 800°C to 20°C.

　　② Water absorption rate: Water absorption ≤16%.

　　③ Lead and cadmium leaching on food-contact surfaces: Lead ≤0.5mg/L, Cadmium ≤0.05mg/L.

　　④ Leakage: For graded products, no water beads form at the base after holding water for half an hour within the glazed area.

　　⑤ Appearance quality: Glaze surface is smooth, with no obvious mesh-like cracks.

　　(2) Arts and crafts category: No requirements for the above physicochemical indicators such as thermal stability or lead and cadmium leaching.

　　3. Safety and other quality and technical requirements: Product safety and other quality and technical requirements must comply with relevant national regulations.