The last step and the most important step in Matcha production is the grinding process. AIYA holds 1300 units of granite stone grinders, and they are maintained by in-house skilled artisans. The grinding process is conducted in a clean room in where the temperature and humidity is closely monitored and controlled as the industrial filters keep the air clean, eliminating bacteria and germs in the air. The average particle size of Matcha powder is only 5-10 microns small. This is so fine (finer than baby powder!) that the powder practically melts in your mouth.
Each stone mill only grinds up to 30-40g (approx. 1 oz) per hour, which is basically the amount of one Matcha tin. Even with all the technology today, the granite stone mill is still the best way to grind Matcha from the delicate Tencha tea leaves, because only granite can preserve the color, flavor, and the nutritional components of the tea to its upmost quality.