Glaze type · Copper & chrome
Copper red (oxblood, flambé)
Across 204 published recipes: mostly cone 10 and cone 9, fired in reduction and oxidation; Glossy, semi-opaque.
Materials that define it
Share of recipes containing each material, and the typical amount when present. Materials link to their reference pages.
| Material | In recipes | Typical | Half of recipes |
|---|---|---|---|
| Copper carbonate | 94% | 0.62% | 0.4–1.45% |
| Tin oxide | 93% | 1.5% | 1–2.27% |
| Silica | 91% | 23% | 16.29–27.43% |
| Whiting | 84% | 11.55% | 8.64–14.93% |
| Bentonite | 44% | 2% | 2–2.96% |
| Custer feldspar | 42% | 44.35% | 36–52.09% |
| Zinc oxide | 42% | 2.94% | 1.74–4.46% |
| Gerstley borate | 37% | 10.2% | 9.1–13.27% |
| EPK | 30% | 5.47% | 2.42–9.14% |
| Nepheline syenite | 28% | 39.38% | 28.39–47.35% |
| Dolomite | 28% | 7.54% | 4.27–8.7% |
| Barium carbonate | 22% | 5% | 4.28–12% |
| Kaolin | 21% | 4.65% | 2–7% |
| Ferro frit 3134 | 20% | 11.3% | 7.48–13.23% |
Typical fired chemistry
Median oxide analysis (weight %) across the recipes that report one, with the interquartile range. Silica and alumina set the melt; the fluxes and colorants make the family.
| Oxide | Median | Half of recipes |
|---|---|---|
| SiO2 | 55.95% | 53.79–58.11% |
| Al2O3 | 10.17% | 8.48–12.44% |
| B2O3 | 2.73% | 2.24–3.72% |
| Na2O | 2.6% | 1.68–4.59% |
| K2O | 3.62% | 2.04–5.1% |
| CaO | 8.66% | 7.72–9.93% |
| MgO | 0.48% | 0.09–1.28% |
| ZnO | 2.94% | 1.74–4.11% |
| SnO2 | 1.47% | 0.98–1.99% |
| CuO | 0.41% | 0.25–0.8% |
What potters should know
Copper goes red in reduction and green to blue-green oxidised; the atmosphere split above is the tell.
Related types
Questions
- What is a Copper red (oxblood, flambé) glaze?
- In 204 published recipes, Copper red (oxblood, flambé) glazes are mostly fired to cone 10 and cone 9 in reduction and oxidation, with a Glossy, semi-opaque result. The defining materials are Copper carbonate, Tin oxide, Silica, Whiting, Bentonite.
- What cone is Copper red (oxblood, flambé) fired to?
- The most common cones in published recipes are cone 10 and cone 9; the full distribution is on this page. Atmosphere matters as much as cone for this family: reduction and oxidation.
- What is the typical chemistry of a Copper red (oxblood, flambé) glaze?
- Median fired analysis: SiO2 55.95%, Al2O3 10.17%, B2O3 2.73%, Na2O 2.6%, K2O 3.62%, CaO 8.66%. Treat these as the centre of a range, not a target — the same family spans different fluxes and cones.
Sources. Every figure is a statistic computed by Claybench over 10,859 glaze recipes compiled from publicly shared community recipe collections (snapshot 2026-02-27); no recipe is reproduced. Colour-chemistry notes are paraphrased from Linda Arbuckle's Ceramic Materials handout.
Colorant and flux notes touch on materials with handling hazards (barium, cobalt, chrome, manganese, lead in historic recipes). Read each material's page and its supplier SDS before mixing; test any food surface.
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