Copper Oxide Red
Packaging: 100 gr (0,22 lb) - 1 kg (2,20 lb) - 5 kg (11,02 lb)
It is one of the oldest coloring oxides.
It is one of the copper-I compounds, where copper is monovalent, and copper-II, where it is divalent.
The molar weight of CuO is 143.14.
It consists of cubic red crystals.
It is insoluble in water.
It is soluble in acids such as HCl, NH4OH.
Its melting temperature is 1235C.
One of the other copper compounds is black copper oxide (CuO).
CuO arises from the combustion of copper or the calcification of nitrate.
This substance, which is a blue precipitate, is used to dye glasses green.
CuO, which forms the red color called ox blood in glazes with copper reaction, gives turquoise blue tones and green colors in the oxidizing firing atmosphere.
When mixed with cobalt in different proportions, it gives all the bluish green tones used in majolica glazes.
Likewise, when mixed with urane and iron, it produces yellowish greens and sparkling greens.
It gives turquoise color in boron glazes. Blue-green tones appear if used with Titan.
In glazes with abundant lithium, blue colored glazes are obtained with copper and its compounds.
In these glazes, copper red can be made in a reducing atmosphere with a small contribution of tin (SnO2).
This oxide, which gives a green color in leaded glazes, creates colors that turn blue with alkalis.
In a reducing atmosphere (reducing) above 1000C, china red can be obtained with very small amounts of copper, zinc and iron oxides.
Copper glazes are very affected by degree differences.
They cause color formation up to red, green and black.
In addition, if decorative firing is applied, they lose their shine and gain a metallic appearance.
The reason for this is that the O2 gas in the furnace at a temperature of 800C during the reducing atmosphere, cooking or cooling, is converted into (CO2) carbon dioxide gas by using a suitable (C) carbon compound and makes it reducing in the oxidizing cooking atmosphere.
Decorating with gilding on glazed pieces containing large amounts of copper presents some difficulties.
For example, if the gilding slips under the glaze, it is not visible.
It has compounds such as copper chloride (CuCl), copper sulfate (CuSO4 5H2O), Copper sulfide (CuS), Copper Titanate (CuO, TiO2).