Glaze type · Traditions & specialties
Synthetic (fake) ash
Across 41 published recipes: mostly cone 10 and cone 6, fired in oxidation and reduction; Glossy, translucent.
Atmosphere
oxidation 58% · reduction 35% · neutral 5% · salt & soda 2%
Surface
Glossy 50% · Semi-matte 15% · Matte 12% · Satin matte 12% · Semi-glossy 12%
Transparency
translucent 41% · opaque 23% · transparent 18% · semi-opaque 18%
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 |
|---|---|---|---|
| Whiting | 83% | 30% | 26.75–40.75% |
| Silica | 51% | 8.1% | 2–12.77% |
| Bone ash | 39% | 5% | 4.13–5% |
| Red iron oxide | 39% | 2.15% | 1.1–4.56% |
| Ball clay | 37% | 24% | 16.1–24% |
| Redart | 37% | 27% | 23–60% |
| Strontium carbonate | 34% | 9.45% | 9–10.5% |
| Dolomite | 32% | 25% | 11.8–25% |
| EPK | 24% | 15% | 4.76–24.7% |
| Ferro frit 3134 | 22% | 10% | 9.55–10% |
| Lithium carbonate | 20% | 2% | 2–2% |
| Custer feldspar | 17% | 21.5% | 20–25.26% |
| Albany slip | 15% | 50.8% | 50–51.7% |
| Talc | 12% | 2.7% | 2.35–6.35% |
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 | 35.51% | 31.8–37.66% |
| Al2O3 | 9.31% | 8.08–11.78% |
| B2O3 | 2.23% | 1.28–2.58% |
| Na2O | 0.66% | 0.46–1.21% |
| K2O | 1.99% | 1.18–2.35% |
| CaO | 18.24% | 13.43–22.84% |
| MgO | 1.99% | 0.9–3.43% |
| SrO | 6.51% | 6.19–7.3% |
| TiO2 | 0.47% | 0.21–0.61% |
| Fe2O3 | 2.82% | 1.81–4.65% |
Related types
Questions
- What is a Synthetic (fake) ash glaze?
- In 41 published recipes, Synthetic (fake) ash glazes are mostly fired to cone 10 and cone 6 in oxidation and reduction, with a Glossy, translucent result. The defining materials are Whiting, Silica, Bone ash, Red iron oxide, Ball clay.
- What cone is Synthetic (fake) ash fired to?
- The most common cones in published recipes are cone 10 and cone 6; the full distribution is on this page. Atmosphere matters as much as cone for this family: oxidation and reduction.
- What is the typical chemistry of a Synthetic (fake) ash glaze?
- Median fired analysis: SiO2 35.51%, Al2O3 9.31%, B2O3 2.23%, Na2O 0.66%, K2O 1.99%, CaO 18.24%. 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.
Claybench checks a glaze against your clay body and cone before it lands on a plan
Recipes, materials, hazards and cone fit — the same reference behind this page, inside the studio planner.