RAKU is a special process that gives the ceramic its final color. Basically, different metal oxides are applied to the ceramic surface, which has already been fired once, and then it is fired a second time. The firing removes chemically bound oxygen from the glaze and clay, which creates numerous special color effects.
The second firing takes place with an open flame, with the ceramic in a red-hot state, at temperatures around 1000 ° C (see the attached pictures), removed from the furnace and covered (throttled) for a few hours. It is covered with earth, leaves and flammable materials (paper, sawdust, etc.) so that it does not re-oxidize in the air. The covered flammable materials create a strongly reducing atmosphere, as a result of which the specially formulated paints applied to the material shimmer in rainbow colors.
The final appearance is determined by numerous tiny circumstances, including where the ceramic becomes colored, metallic or matte, where the glaze cracks, etc. The unglazed ceramic turns gray or black upon firing. Few works pass the test, so few risk the work, but if it succeeds, the result speaks for itself. After the final cooling, the glaze reaches its final state. After we have finally rubbed off the soot, we can hold a beautiful object in our hand. It looks like a relic that is several thousand years old. Whoever possesses this knows that his is unique ...