There are two purposes of tea leaf rolling: to moderately crush the internal tissues of the leaves so as to let the internal substances penetrate up to the external surface and to mold the contour of tea so as to make the leaves and buds curl into required shapes. High-quality green tea is usually rolled by hand. The more tender leaves are rolled after cooling the deactivated leaves while the less tender leaves are rolled when the leaves are still warm. The pressure on the tea is relieved in the later period of rolling, and finally, the clusters of the rolled tea are scattered to prepare for desiccation. For low and medium grades of green tea, rolling machines are generally applied.