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Copper glaze: Chemical reaction and captivating red

13 September 2015

 I want to be a scientist at the same time being a ceramicist. Fujimoto Gakuei describes himself in the interview.

 Chemical reactions occurring on colouring agents in kilns generate diversity of ceramic art. The firing and percentage of agents change colours, and minor differences of such conditions greatly affect the reactions. In other words, adjustment of firing and glazing are so sensitive that making stable reaction and creating target colours are not easy to achieve.

 For instance, while oxidisation firing changes copper glaze to green which is used for Oribe and other green decorations, reduction firing changes it to red which is called oxblood, flanbe or peach bloom. Amount of other ingredients as well as percentage of copper oxide in glazes vary colours from red, pink purple to green, blue and black. The photos show peach bloom and oxblood (tokako and shinsha are the names of these glazes in Japanese) bowls produced by Fujimoto Gakuei. After numerous trials and errors, he established his firing technique and glazing recipes for yuriko (copper underglaze), shinsha and tokako.

 Originated in China for imperial use, the copper red ceramic ware was introduced to France, where it was replicated in the 19th century and called oxblood. As is represented in its name, the oxblood glaze turns in blood-red with dappled blackish shades. Fujimoto's shinsha is bright and clear red with no unevenness of colour. He executes his tokako in painting style with the glaze that has gracefully gradating colours from red to green whereas authentic tokako glaze is thickly applied on entire surface of vessels. Fujimoto's copper red is a modern interpretation of a historical glaze.

 Firing process creates chemical reaction that results in excellent colours on ceramics. No matter if they know chemical formulae or not, their practical knowledge makes potters experts of applied chemistry who can create pieces of art.

Hirado Tousyo Fujimoto Gakuei's interview

Hirado Tousyo's works