Copper Oxide


Transparent green will be produced when firing in a neutral or oxidising atmosphere, except in alkaline glazes such as Raku glazes, when a turquoise blue is produced darkening considerably in strongly alkaline ones. In a reduction firing a copper red colour is produced known as sang de boeuf.

The test tile shown is buff clay showing a white slip on one side and then the JSC earthenware transparent brush on glaze with the oxide brushed on top of the glaze and raw (once) fired.

NOTE – when added to low solubility glaze , copper causes the solubility of the glaze to be greatly increased ,making it unsuitable for use on domestic wares in contact with food or drink. There is no problem with copper in leadless glazes. 1 -5 %addition.