- Very active flux
- Disperses well in glaze
- Although melts at 2098°F, another popular form, copper carb, melts at 932°F and changes to copper oxide
- Copper can produce many colors like red, pink, green, blue, black and metallic lusters
- Used alone it can produce reds in heavy reduction
- with the addition of small amounts of tin oxide (.3%) or iron oxide, it’s even more effective in making reds.
- In a sodium base, it will produce blues
- In strike firing cycle it will produce metallic lusters
- Extremely sensitive to oxidation or reduction firings
- Because heated copper oxide molecule releases an oxygen atom fairly easily which is then transformed into a reduced state such as Cu2O or even copper metal (Cu)
- Volatilizes at high temps
- In this state, material is called fugitive copper
- As it swirls throughout kiln the copper may be picked up by other pots, causing flashes of red or pink on them
- Particularly ones that have tin oxide in the glaze
- High expansion and contraction rate may cause glaze crazing
- Disperses easily in glazes, producing uniform color
- Black copper oxide
- because of its course mesh size, causes speckling
- Red copper oxide
- strongest of all copper oxides
- difficult to mix with water because it is coated to halt oxidation during storage
- few drops of dish soap in glaze water will assist in dispersing red copper oxide
- Black copper oxide
- For substitution purposes
- 113g copper sulfate=100g of carbonate=72g black = 64.7g of red oxide
- Copper materials are available from most ceramic suppliers in several forms
- copper carbonate (CuCO2) a green, 200-mesh powder
- black copper oxide (CuO) 100-mesh
- Red copper oxide (Cu2O)
- available in 200 mesh,
- though grades offered will vary by supplier
- Can also obtain copper sulfate
- water-soluble blue crystal that is used as agricultural poison
- Copper materials are toxic and should be handled with care
