Wilco UPF Kaolin
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Clays
- Formula
- SiO₂ 45.7%, Al₂O₃ 38.4%, Fe₂O₃ 0.4%, TiO₂ 1.5%, CaO 0.1%, MgO 0.1%, Na₂O 0%, K₂O 0.2%, LOI 13.65%
- Also called
- Wilco UPF, Wilco UPF Georgia Kaolin, Old Hickory Wilco UPF, UPF kaolin
- Made by
- Old Hickory Clay Company (kaolin mined in Georgia)
- Sold in
- US
- Similar materials
- Tile #6 Kaolin , EPK Kaolin
- Replaces
- EPK Kaolin
- Source
- Old Hickory Clay Company, Typical Data Sheet (ball clays and kaolin clays) (2026-07)
A white-firing Georgia kaolin that US suppliers now stock in place of EPK. Potters report one-for-one swaps for EPK in cone 6 and cone 10 glazes with little visible change, though it carries more TiO2 (1.5%) than EPK (0.4%).
Oxide analysis and unity formula
Glazecalc has the analysis of Wilco UPF Kaolin as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Wilco UPF Kaolin that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| SiO₂ | 45.7 | 119.076 |
| Al₂O₃ | 38.4 | 58.960 |
| Fe₂O₃ | 0.4 | 0.392 |
| TiO₂ | 1.5 | 2.940 |
| CaO | 0.1 | 0.279 |
| MgO | 0.1 | 0.388 |
| K₂O | 0.2 | 0.332 |
- Equivalent weight
- 15,655.18
- Fired weight
- 13,518.25
- Loss on ignition
- 13.65%
The equivalent weight is the grams of Wilco UPF Kaolin 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 (quartz); do not breathe the dust.
Use it in a recipe
Add Wilco UPF Kaolin to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.