窯炉内雰囲気が釉の発色に及ぼす影響

Abstract

This paper is concerned with the relation between color of glaze and the atmosphere in the furnace. In order to clarify the relation, the furnace which was able to control the ratios of CO gas to N_2 gas was prepared, and the porcelain body and glaze were fired at temperatures in the range of 950∿1200℃ in various reducing atmospheres containing CO in the furnace and the effect of the reducing atmosphere on the color of glaze was judged by means of the color analyser. As for reducing atmosphere the mixture gas of N_2 and CO (percent of CO=5∿20%) was used and the other atmosphere only N_2 gas was used. Experimental results are summarized as follows : (1) In the celadon it was found that the color of glaze varied from blue to green with an increasing CO% in the atmosphere. In a reducing atmosphere containing 10% CO the color of glaze was green below 1100℃, blue at 1100℃ and also turned light brown above 1100℃. (2) The transparent glaze and porcelain body assumed most white color in a reducing atmosphere containing 10% CO at 1100℃. (3) It was confirmed that iron contained in the glaze vaporized easily like copper under the condition of reducing atmosphere at 950∿1200℃.