Koudai

Koudai is the part of bottom which touched with ground. It supports work from under ,so to keep firmly or not is depend on koudai. Koudais have verious patterns. Commonly koudai's shape is circle but sometimes square like. Famous AritaYaki works are tend to be alike ratio of kodai's size. (in details, 1:3:1=width : inside circle diameter : width
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Coloring

What makes the color of pottery so vivid  and light? It depends on a glaze. Glazing is to cover the surface of works with  thick glaze. So many things can be used as the ingredients of glaze and each items and its ratio are very important  to decide the color of works.

For example, Ruri, strong blue like the color of ocean, is made by the following recipe:

                                                                                                                    

English name (Japanese name)
Feldspar(Tyoseki)  35%

Cabonic barium (Tansan bariumu)12%

Kaolin(kaorin) 8%

Silica stone(Fukushima tyouseki) 30%

Cobalt oxide(Sanika kobaruto) 5%

There are so many traditional coloring techniques in Japan.