Calcium Borate Frit (CTM 37)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Frits
- Status
- Discontinued
- Formula
- SiO₂ 17.9%, B₂O₃ 50.3%, MgO 0.1%, Al₂O₃ 4.9%, K₂O 0.3%, CaO 26.5%
- Also called
- CTM 37
- Sold in
- UK
- Similar materials
- Gillespie Borate , Calcium Borate Frit (Potterycrafts P2954) , Calcium Borate Frit (Potclays 2268) , Ferro Frit 3134 , Ferro Frit 3195
- Source
- CTM Potters Supplies retail price list, 23 August 2019 (frit 37 analysis) (2019-08)
CTM's calcium borate frit, on sale until at least 2019 and 'not available' by December 2025. The analysis is the one CTM's price lists printed from 2016 to 2026 (the same as Potterycrafts P2954); CTM's frits web page gives an older one (SiO₂ 24, Al₂O₃ 8, B₂O₃ 41, CaO 22). CTM suggests, for every 100 g removed from a recipe: add 167 g Gillespie Borate and 10 g quartz, and take out 12 g whiting and 26 g potash feldspar, then test.
Oxide analysis and unity formula
Glazecalc has the analysis of Calcium Borate Frit (CTM 37) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Calcium Borate Frit (CTM 37) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| SiO₂ | 17.9 | 0.623 |
| B₂O₃ | 50.3 | 1.511 |
| MgO | 0.1 | 0.005 |
| Al₂O₃ | 4.9 | 0.100 |
| K₂O | 0.3 | 0.007 |
| CaO | 26.5 | 0.988 |
- Equivalent weight
- 209.1
- Fired weight
- 209.1
- Loss on ignition
- 0%
The equivalent weight is the grams of Calcium Borate Frit (CTM 37) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Not classified (CTM SDS 37); avoid breathing the dust.
Use it in a recipe
Add Calcium Borate Frit (CTM 37) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.