Copper Oxide Red

Red copper oxide is cuprous oxide, the most concentrated of the three copper additions we stock, with more copper by weight than black copper oxide and more again than copper carbonate. Nine parts of it stand in for ten parts of the black oxide. It is usually bought for reduction and raku work, though copper carbonate is the finer grind and appears in more copper red recipes than this does, so the choice between them comes down to grind and price, not colour. In an ordinary oxidation firing it finishes the same green as black copper oxide. In the bucket it behaves differently from the other two, because the powder floats on the water instead of mixing in. A drop or two of detergent breaks the surface tension and it disperses. Like all copper it is a strong flux and evaporates above about cone 8.