Cornish Stone (synthetic substitute)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Feldspars and stones
- Formula
- SiO₂ 73.66%, TiO₂ 0.02%, Al₂O₃ 15.81%, Fe₂O₃ 0.14%, MgO 0.14%, CaO 0.28%, K₂O 4.27%, Na₂O 4.31%, LOI 1.39%
- Also called
- FCS2, Synthetic Cornish Stone, Potterycrafts P3314, Valentine FL004, CTM 46 Cornish Stone, Synthetic, Bath Potters Cornish Stone
- Sold in
- UK
- Replaces
- Cornwall Stone
- Source
- Valentine Clays technical data sheet 'Cornish Stone' (FCS2, water ground; mean values from QC results) (2024-07)
Natural Cornish stone is no longer quarried, so UK suppliers now sell a substitute. Valentine's FCS2 is 'a milled material composite flux designed to match the firing characteristics of Cornish Stone'; it melts 1100-1300 °C.
Oxide analysis and unity formula
Glazecalc has the analysis of Cornish Stone (synthetic substitute) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Cornish Stone (synthetic substitute) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| SiO₂ | 73.66 | 9.940 |
| TiO₂ | 0.02 | 0.002 |
| Al₂O₃ | 15.81 | 1.257 |
| Fe₂O₃ | 0.14 | 0.007 |
| MgO | 0.14 | 0.028 |
| CaO | 0.28 | 0.040 |
| K₂O | 4.27 | 0.368 |
| Na₂O | 4.31 | 0.564 |
- Equivalent weight
- 810.78
- Fired weight
- 799.51
- Loss on ignition
- 1.39%
The equivalent weight is the grams of Cornish Stone (synthetic substitute) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Fine dust contains respirable crystalline silica; avoid breathing it.
Use it in a recipe
Add Cornish Stone (synthetic substitute) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.