Synthetic Rice-Straw Ash (合成藁灰)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Fluxes
- Formula
- SiO₂ 81.46%, Al₂O₃ 6.52%, Fe₂O₃ 0.14%, CaO 2.83%, MgO 1.1%, Na₂O 1.7%, K₂O 1.65%, LOI 4.6%
- Also called
- 合成藁灰, 合成ワラ灰, 合成わら灰, gōsei warabai
- Sold in
- JP
- Source
- 佐賀県陶磁器原料株式会社 (Arita): 釉薬原料の化学分析表, the supplier's typical analysis of what it sells (undated; read 2026-11-04). Second analysis: 吉田博和ほか「笠間焼の新素地・新釉薬の開発」, 茨城県工業技術センター研究報告 43 (2014), 表6
A typical analysis from one supplier in Arita: check it against your own supplier's. A synthetic stand-in for 藁灰, the rice-straw ash that makes Japanese glazes milky; it is mostly silica. The supplier's figures add up to 97.1%, so the 2.9% they leave out is counted here as lost on firing, with its LOI of 1.7%. A 2014 analysis by the Ibaraki industrial technology centre of another 合成藁灰 was much the same: SiO₂ 80.6%, Al₂O₃ 7.7%, CaO 2.9%, LOI 1.5%.
Oxide analysis and unity formula
Glazecalc has the analysis of Synthetic Rice-Straw Ash (合成藁灰) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Synthetic Rice-Straw Ash (合成藁灰) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| SiO₂ | 81.46 | 11.049 |
| Al₂O₃ | 6.52 | 0.521 |
| Fe₂O₃ | 0.14 | 0.007 |
| CaO | 2.83 | 0.411 |
| MgO | 1.1 | 0.222 |
| Na₂O | 1.7 | 0.224 |
| K₂O | 1.65 | 0.143 |
- Equivalent weight
- 814.97
- Fired weight
- 777.48
- Loss on ignition
- 4.6%
The equivalent weight is the grams of Synthetic Rice-Straw Ash (合成藁灰) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Contains crystalline silica; avoid breathing the dust.
Use it in a recipe
Add Synthetic Rice-Straw Ash (合成藁灰) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.