Glaze type · Traditions & specialties
Ash glaze
Across 224 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 |
|---|---|---|---|
| Wood ash | 76% | 35% | 25–50% |
| Silica | 37% | 12.5% | 7–20% |
| Whiting | 35% | 18% | 11.08–28.88% |
| EPK | 26% | 13.5% | 10–20% |
| Custer feldspar | 22% | 30% | 17.69–37% |
| Ball clay | 21% | 13.5% | 11.27–20% |
| Bentonite | 16% | 2% | 2–2% |
| Potash feldspar | 16% | 26.81% | 11.64–38.6% |
| Rutile | 15% | 3% | 1–4.5% |
| Dolomite | 14% | 10% | 7.08–19.52% |
| Red iron oxide | 14% | 3% | 2–6% |
| Kaolin | 13% | 20% | 8.05–36.5% |
| Gerstley borate | 13% | 12.61% | 9.79–17.29% |
| G-200 feldspar | 12% | 30% | 20–40% |
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 | 42.33% | 33.72–48.35% |
| Al2O3 | 9.99% | 7.79–12.69% |
| Na2O | 3.23% | 1.71–4.04% |
| K2O | 9.91% | 4.54–13.11% |
| CaO | 10.8% | 8.45–17% |
| MgO | 2.79% | 1.97–3.92% |
| P2O5 | 4.13% | 1.78–6.54% |
| TiO2 | 0.32% | 0.11–0.67% |
| Fe2O3 | 3.69% | 1.71–5.55% |
Related types
Questions
- What is a Ash glaze glaze?
- In 224 published recipes, Ash glaze glazes are mostly fired to cone 10 and cone 9 in reduction and oxidation, with a Glossy, semi-opaque result. The defining materials are Wood ash, Silica, Whiting, EPK, Custer feldspar.
- What cone is Ash glaze 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 Ash glaze glaze?
- Median fired analysis: SiO2 42.33%, Al2O3 9.99%, Na2O 3.23%, K2O 9.91%, CaO 10.8%, MgO 2.79%. 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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Recipes, materials, hazards and cone fit — the same reference behind this page, inside the studio planner.