Japanese reading: hunsai houhou

Matcha is generally ground using two main methods: stone milling and mechanical grinding. Stone milling produces a small output (around 40–50 g per hour) but is associated with high-quality matcha. Mechanical grinding can produce much larger volumes (roughly 10–15 kg per hour, depending on equipment scale).

Japanese reading: ishiusu biki
A method of grinding tencha into matcha using a stone mill. Although the hourly output is low, it tends to produce aromatic, deep-flavored, high-quality matcha. It is also well-suited to small-batch, multi-variety production. (At Matcha Direct, most matcha is stone-milled.)

Japanese reading: kikai biki

A method of producing matcha in large volume within a short time using grinding machines. Average particle size can be controlled to some extent, and the particle size distribution can be made relatively narrow. Traditionally, it was considered inferior to stone milling in quality, but newer machines with cooling mechanisms (e.g., grinding while circulating chilled water) can achieve quality closer to stone-milled matcha. In practice, settings are often optimized for productivity, so the particle size is usually not as fine as typical stone milling.

Japanese reading: ishiusu

A tool used to grind tencha into matcha slowly and finely. Tencha is fed from the center and ground in one direction as it moves toward the outer rim.

Typical reference points include:

• Groove intersection angle: typically 45°, often considered efficient
• Rotation speed: 50–55 rpm
• Particle size range: approximately 2–100 microns, with variability
• Output: 40–50 g per hour
• Common standard size: 1 shaku 1 sun in diameter (approx. 33.3 cm)

Fig. Each machine can grind only around 40 g per hour, so production volume is increased by operating multiple machines.

Japanese reading: biizu miru

A type of mechanical grinder in which a cylindrical chamber is filled with metal or ceramic beads. Tencha is ground by high-speed impact and friction against the beads. Bead size may be staged (smaller toward the outlet). The equipment is relatively compact.

Japanese reading: bouru miru

A type of mechanical grinder that uses larger balls (compared with beads) made of metal or ceramic to grind tencha. The equipment tends to be larger, and operating noise is typically higher.

Japanese reading: hammaa miru

A type of grinder with an uneven inner wall where hammers attached to a rotating shaft spin at high speed and pulverize tencha by impact. The powder is typically collected using a bag filter system.

Japanese reading: kiryuushiki miru

A grinding method that generates a high-speed airflow inside the mill, causing tencha particles to collide with each other and break down. It is compact, efficient, and suitable for large-scale production.

Japanese reading: ryuudo

The average size of particles (expressed as a mean value because actual particles vary in size). As a general reference, stone-milled matcha is often around 6–15 microns but is difficult to control precisely and can vary by mill characteristics. Mechanically ground matcha is often around 15–25 microns and can be controlled to some extent; it can be set as fine as stone-milled, but this is not commonly done when prioritizing efficiency.

Japanese reading: hurui

A tool used after grinding to remove foreign matter and larger particles. Because particle size always has a distribution (both for stone milling and mechanical grinding), particles around 200 microns or larger may be present. To maintain consistent particle size, matcha is commonly passed through sieves such as 60–100 mesh (Matcha Direct typically uses 60–80 mesh).

Japanese reading: messhu

A unit that indicates the opening size (fineness) of a sieve.

Japanese reading: shaku

A traditional Japanese unit of length. As a reference, 1 shaku is about 30 cm and 1 sun is about 3 cm. Many modern standard stone mills are approximately 1 shaku 1 sun in diameter (about 33.3 cm), a size that became standardized through experience.

Japanese reading: usuha

The leaf portion of tencha that is ground into matcha in a stone mill. Harder parts such as stems and leaf veins are called “ore.” If ore is mixed in, it can cause the mill to chatter and the grind to become coarser, so removing ore is emphasized during finishing.

Fig. Using only the leaf portion and ensuring a uniform size makes the material ideal for stone milling.

Japanese reading: metate

Maintenance work in which the grooves of a stone mill are reconditioned as they wear down over time. Traditionally done by skilled craftsmen, it may also be adjusted using laser-based methods in recent years.

Japanese reading: kime

The ungrooved area near the outer rim of a stone mill (about 1 cm wide). It is a critical zone that determines the final fineness of matcha; very fine particles (on the order of a few microns) are produced here.

Fig. The outer peripheral area of the millstone cross-section (highlighted in orange) has no grooves and is referred to as the “Kime.”

Japanese reading: shingi

The central spindle of a stone mill. Tencha fed from the center moves outward while being ground between the upper and lower stones. Over long use, the spindle can wear thinner, causing the upper stone to wobble and misalign the kime areas. As a result, insufficiently ground larger particles (around 100–200 microns) may pass through. Regular replacement and careful management of the spindle are important.

Fig. The wooden shaft at the center is the Shingi.