Processing
Tencha
The raw material for matcha: shade-grown leaf that is steamed and then dried without rolling. Veins and stems are removed and the remaining leaf flesh is stone-milled into matcha. Tencha is occasionally brewed and drunk as it is.
In more detail
Tencha is dried in a dedicated furnace. Because it is never rolled, it stays as large, flat flakes. Veins and stems are then separated out by air and sieving, and only the leaf flesh goes to the mill, which turns at around fifty revolutions a minute. Faster generates heat that drives off the aroma, so a mill yields roughly 40 g an hour. That step is most of what matcha costs.