The first Banko was made back in 1736. It was started in Yokkaichi City of Mie Prefecture. Banko is baked with Reduction Furnace. It gives very limited oxygen into the kiln. With the reduction furnace, the mineral, in particular Iron inside the clay changes to blue in color. The oxidized iron is reddish in color, and when blue color mixed with this reddish color, teapot appears to be shinny and slight purple in color.