Copper Oxide Red

Alternate Names: Cu₂O, Red Copper, RCO, Copper (I) Oxide, Cuprous Oxide

Oxide	Analysis	Formula
Cu2O	100.00%	1.00
Oxide Weight		143.00
Formula Weight		143.00

Notes

Red copper is a reduced form of the normal black copper oxide (CuO). In normal oxidizing firings it will transform to the cupric oxide form (CuO) to produce the normal green coloration in glazes and glass. If fired in reduction, it will maintain its Cu₂O structure to produce the typical copper red color. See CuO, Cu₂O oxides for more information.

A conversion factor for red and black copper oxide: It might seem that it would simply be a division of the weights, Cu₂O/CuO, 143 / 79.54 = 1.798. But not so, the conversion factor is actually 1.12 black copper for red. CuO (black copper) has a weight of 79.5 (1 copper weighing 63.5 + 1 oxygen weighing 16). Cu₂O weighs 143, it has two atoms of copper (double what CuO has), thus it sources 127 Cu (copper) from that 143 total. 143 weight units of CuO would source only 113.7 Cu (63.5*143/79.5=113.7). So the conversion factor is 127/113, or 1.12.

Note: Red copper oxide is usually surface coated to prevent oxidation. For this reason, it may be very difficult to get the material to mix with a glaze slurry. If so you must soak the material in alchohol to wash the surface. Or use soapy water and then rinse with clean water (so there is no soap in the glaze slurry).

See also: "Coloring Mechanism of Peach Bloom Copper Red Glazes" written by four technicians from China published in Dec 91 Bulletin of the American Ceramic Society.

Related Information

Links

Articles	Leaching Cone 6 Glaze Case Study An example of how we can use INSIGHT software to determine of a glaze is likely to leach
Materials	Copper Carbonate A source of CuO copper oxide used in ceramic glazes to produce a variety of colors (used only or with other colorants).
Materials	Copper Oxide Black The purest source of CuO copper oxide pigment used in ceramic glazes.
Materials	Copper Carbonate Basic This form of copper carbonate is the article of commerce, a mixture of theoretical copper carbonate and copper hydroxide.
Hazards	Copper Oxide and Carbonate
Hazards	Copper Compounds Toxicology
Temperatures	Copper oxide melts (1325-)
Typecodes	Generic Material Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Typecodes	Colorant Metallic based materials that impart fired color to glazes and bodies.
Oxides	CuO - Cupric Oxide
Oxides	Cu2O - Cuprous Oxide

By Tony Hansen
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