Copper Carbonate 100 g
CuCO3. mol. 221 (100g-1kg-25kg)
Can be used as copper oxide, but is finer grinded so that the specks in the glaze can be avoided. Reduction of a copper glaze will be easier when carbonate is used instead of the oxide.
In oxidized firings the copper normally produces green colors, except for alkaline glazes where it will be turquoise, but amounts +5% it gets darker and moves towards black. In reduction firing, it turns to Cu2O and gives beatiful red hues. In temperatures above 1020°C, the copper becomes increasingly volatile and its crystalline structure breaks down.
This can affect the color of other glazes in the kiln.