Clay Pimples (爆子) and Jumping Sand (跳砂)

Clay pimples (爆子, baozi, “clay pops”)^[1] and jumping sand (跳砂, tiaosha)^[2] are two minor flaws found on the outer surface of zisha wares. Both flaws originate from the same root-cause: larger grains of zisha clay shrinking less during firing then the surrounding material. The larger grains may originate from variations in particle size during traditional hammer^[3] or grindstone milling, from the addition of coarse grains into zisha clay for the tiaosha (调砂) textural or visual effect, by the removal of medium sized grains for texture modification in the chousha (抽砂) method^[4], or in the addition of pre-fired and re-milled grog (熟砂, shu sha, “ripe sand”) for textual modification of certain clays^[5].