The art and science behind treasured Japanese porcelain

Since the early 17th century, master potters have honed their techniques for creating akae ceramics by trial and error, and then passed on their methods to their apprentices. The quality of the resulting porcelain varies, however. In a search for a more reliable way to make superior akae, a few studies have probed the underlying structure that makes the best red ceramics. But they didn't clarify the essential coloring mechanism. Hideki Hashimoto and colleagues wanted to gain a deeper understanding of what makes the most distinctive akae.

The researchers experimented with different methods for making red coloring with hematite and a lead-free glass frit, a ground material used to make glazes and glass. They found that the sizes of hematite particles and of the frit powder played an important role in color quality. Based on their results, the researchers developed a simple process for preparing red paints for creating exceptional akae. It involves mixing hematite, frit powder and a solvent three times with a mortar and pestle, instruments commonly used by porcelain artisans. Because the method is simple, the researchers say today's potters could easily adopt it.