Characterization of Buleleng clay and improvement of its ceramic properties

Purpose. The research focuses on the improvement of local clay-based ceramic pottery bodies from Alas Angker in Buleleng Regency in Bali. The main purpose is to utilize the clay which meets the standards of ceramics such as smooth and hard earthenware, especially to reduce its water absorption property. Methods. Firstly, the clay is analyzed for its physical and chemical composition. Two ceramic body formulations are made using the clay with the BWNAA1 and BWNAA2 codes. The specimens are measured in terms of clay ceramics properties including plasticity, dry shrinkage, firing shrinkage and water absorption. The cracked ceramic products are also analyzed for a comparison. Findings. The ceramic properties show similar results, except for the water absorption percentage. The BWNAA2 code formulation has lower water absorption rate by 10.8% and meets the requirements for the type of smooth and hard earthenware body in compliance with the national standard SNI:7275-2018. The water absorption rate is about half of the existing products, which is effective in avoiding the problem of cracks. Originality. Comparison of the existing ceramic products and specimens made in this study shows a significant difference in water absorption and crack growth. Adding a certain amount of kaolin, feldspar, ball clay and quartz sand has significantly reduced the water absorption rate of ceramic bodies. Practical implications. This research can be a potential solution to increase the quality of ceramic pottery products in the vicinity of Buleleng Regency which use the clay of this kind.