Lead Bisilicate Frit (Potclays 2261)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Frits
- Formula
- PbO•2SiO₂ (plus about 2.5% Al₂O₃)
- Also called
- Lead Bisilicate, Lead Bisilicate Frit, Lead alumina bisilicate, Potclays 2261, Bath Potters Lead Bisilicate, CTM 34 Lead Bisilicate Frit
- Sold in
- UK
- Source
- Potclays, 'Frit Formulae' technical sheet (John Beeston, January 2010), Internet Archive copy of 2013 (2010-01)
A 'true' lead bisilicate (65-66% PbO, 32% SiO2, 2% Al2O3) still sold in the UK as the usual frit for low-solubility earthenware glazes; firing 880-1050 °C (Potclays).
Oxide analysis and unity formula
Glazecalc has the analysis of Lead Bisilicate Frit (Potclays 2261) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Lead Bisilicate Frit (Potclays 2261) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| PbO | 65.04 | 1.000 |
| Al₂O₃ | 2.55 | 0.086 |
| SiO₂ | 32.4 | 1.851 |
- Equivalent weight
- 343.17
- Fired weight
- 343.17
- Loss on ignition
- 0%
The equivalent weight is the grams of Lead Bisilicate Frit (Potclays 2261) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
This material contains lead oxide (PbO).
Hazards: Lead frit: toxic if the dust is breathed in or swallowed. Fired glazes can release lead into food and drink; UK suppliers say low-solubility glazes are not food safe by default and ware must be metal-release tested.
Use it in a recipe
Add Lead Bisilicate Frit (Potclays 2261) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.