Antimicrobial effect of porcelain glaze with silver-clay antimicrobial agent

Antimicrobial activities of porcelain glazes with antimicrobial agents made of clay minerals intercalated with silver chelate and the effect of additives to the antimicrobial agents on those activities were investigated. The glazes with 10 mass% antimicrobial agents, fired at 1573K in a reducing atmosphere, showed negative antimicrobial activities. On the other hand, the antimicrobial activities of the glazes with 110 mass% of the agents fired in an oxidizing atmosphere were positive. The glaze with an agent doped with Zr had a high antimicrobial activity by adding only 0.2 mass% of the agent, which included only 0.008 mass% Ag in the glaze. Wavelength-dispersive X-ray fluorescence, used for ingredient analysis, showed that the negative activity resulted from the disappearance of the Ag in the glaze fired in the reducing atmosphere.