In ceramics this strong oxide produces a transparent apple green colour under neutral or oxidising conditions, except in alkaline glazes when it produces a turquoise blue. In reduction a copper red colour is produced known as 'sang de boeuf'.
Please note that 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.
HARMFUL (Xn). Please read the safety information prior to purchase and use: