Installing/repairing the higuchi (tuyere), the point where the air enters the forge and temperatures are very high. In this case the fire clay to form the tuyere and fit it to the brick construction Japanese swordsmith forge is a traditional brasque recipe consisting of 6:2 charcoal powder/fines to natural clay, mixed with just enough water to stick together well. The forge must be allowed to dry fully before lighting or steam will crack the clay. see more of the island forge kajiba project