Agrawal, Parvesh and Anil, Asha and Solanki, Parag and Kundariya, Haresh and Prasad, Abhijit (2022) Technical Assessment of Terracotta Clays Used by Rural Potters in Gujarat. Indoceram of AIPMA, 9 (3). pp. 47-64. ISSN 2321-1970

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Gujarat has about 5000 families engaged in the manufacturing of terracotta pottery. A Survey of rural potters and characterization of their terracotta raw materials carried out in Integrated Pottery Development Project (IPDP) revealed a lot of important technical information regarding terracotta manufacturing. Traditional handicraft rural pottery in Gujarat is faced with range of technical problems related to its manufacturing process. The pond clay and farm clay used by rural potters are soils. Main clay minerals in these soils are kaolinite, muscovite-illite, and Smectites associated with quartz, goethite, feldspars, and anatase. Black soil is the most dominant soil type in Gujarat. The main parent rocks in red soils are crystalline and metamorphic rocks like acid granites, gneisses and quartzites. The red soils are mostly loamy and hence cannot retain water like the black soils. The red colour is more due to the wide diffusion rather than the high percentage of iron oxide content.Alluvial clays were easily available near the rivers, sea, and ponds and are natural body mixes suitable for throwing. The potters residing in areas short of alluvial clays utilize mixtures of black soils and red soils. Plastic and dry properties of black, brown and red terracotta clays from Gujarat showed an increasing trend along with increase in particle fineness. Major shrinkage of terracotta products takes place during the drying process only. Firing shrinkage at 800°C is very less and no consolidation of material takes place during firing. Porosity is increased due to the burning of organic matter and evaporation of mechanical and chemical waters. The average water absorption remains in the range of 14 to 16% when fired at 800°C. Terracotta clays undergo irreversible changes when fired above 600°C. Black terracotta clays have a significant amount of calcite and higher Na2O content causing them to bloat when fired at higher temperatures. A higher quantity of calcite in black clays is also responsible for higher drying and firing rejections.

Item Type: Article
Subjects: Structural Clay Products
Depositing User: Bidhan Chaudhuri
Date Deposited: 09 Nov 2022 05:43
Last Modified: 09 Nov 2022 05:43

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