New route to lead-free porcelain designs discovered

Akae is a traditional Japanese enameling technique used to decorate porcelain. Historically, it involved combining leaded glass powder with iron(III) oxide in a water-based solution to yield a red paint. As porcelain makers have tried to switch to lead-free glass, however, they have had trouble producing high-quality akae samples. Experiments combining various particle sizes of glass and iron(III) oxide now seem to provide an optimal recipe that yields a glass particle core coated with an iron(III) oxide shell, reports a team led by Hideki Hashimoto of Kogakuin University. In contrast, the researchers find that preparing akae paint such that the iron oxide is isolated in spaces between glass particles results in a lower quality enamel (ACS Appl. Mater. Interfaces 2016, DOI: 10.1021/acsami.6b01549). The group succeeded in preparing the core-shell material by combining 2-µm glass particles with 100-nm iron(III) oxide particles, but the details of the preparation method were key: They blended the particles with green tea solution in a mortar and let the mixture dry, repeating the process a total of three times. Because mortars and pestles are commonly used by porcelain artisans, the authors believe that the method should be easy to implement.