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Copper Carbonate

Copper Carbonate

Stock Status: In Stock
100g, 500g, 1Kg and 5Kg Packs
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(CuCO3) is bulkier than the oxide form, thus it tends to disperse better to give more even results. It is also more chemically reactive than the oxide form and thus melts better. As such, it is ideal for use in brush work where minimal speck is required. However it produces gases as it decomposes and these can cause pinholes or blisters in glazes.

Also the carbonate form contains less copper per gram, therefore colours are less intense than the oxide form. Supplies of green copper carbonate often vary in colour and density. Despite variations in the physical appearance of the material, the amount of contained copper metal remains essentially constant but the ability to stay in suspension can be different from one manufacturer to another and so the ceramic grade must always be used.
Copper normally produces green colours in amounts to 5% whereafter it moves toward black. In reduction firing, it turns to Cu2O and gives vibrant red hues. Above 1025C copper becomes increasingly volatile and its crystalline structure breaks down. At 1325C CuO melts. This can affect the colour of other glazed pieces in the kiln. Glazes containing copper can change significantly because of loss of copper. Some potters alternate between reduction and oxidation, and even put a dish filled with copper carbonate in the centre of the kiln to minimize this phenomenon. It can act as a strong flux. It is the most stable form of oxidized copper ( Black Cuprous oxide oxidizes to Red cupric oxide in normal firings). The oxide form of copper can give a speckled colour in glazes whereas the carbonate form will give a more uniform effect.