Kaki (persimmon) glazes are high fired reduction transparents with a generous supply of iron oxide (12% or more) which forms a microcrystalline surface. If cooled correctly they exhibit "red" coloration. The atmosphere during cooling should be reduction. The iron content of the body and level of reduction affect the fired results. Tenmoku glazes are closely related, however they have less iron oxide (around 10%) so that crystallization occurs on the edges of pieces.
Tenmoku is a kind of ceramic glaze. Glossy, very dark brown or maroon, edges crystalizing, firing at high temperature in reduction atmospheres.