German Kaolin (Bodmer Ton 539)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Clays
- Formula
- SiO₂ 52.5%, Al₂O₃ 32.8%, K₂O 2.9%, Fe₂O₃ 0.4%, TiO₂ 0.4%, Na₂O 0.1%, LOI 10.7%
- Also called
- Kaolin (Bodmer Ton), Bodmer Ton Kaolin 539, Bodmer 539, Deutscher Kaolin
- Made by
- Not named; sold by Bodmer Ton AG (Einsiedeln, Switzerland) as German kaolin
- Sold in
- EU
- Similar materials
- Zettlitz Kaolin (Sedlec Ia) , China Clay , Grolleg China Clay
- Source
- Bodmer Ton AG technical data sheet 'Technisches Datenblatt Kaolin, Artikel 539' (Stand Juli 2025) (2025-07)
The plain 'Kaolin' that Bodmer Ton, a large Swiss pottery supplier, sells alongside its English china clay. It is coarser and less plastic than Cornish china clay (only 19% finer than 2 microns) and has more silica and potash (2.9% K2O), so it adds a little flux. Used to bring alumina and silica into glazes and for white engobes.
Oxide analysis and unity formula
Glazecalc has the analysis of German Kaolin (Bodmer Ton 539) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of German Kaolin (Bodmer Ton 539) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| SiO₂ | 52.5 | 26.968 |
| Al₂O₃ | 32.8 | 9.929 |
| K₂O | 2.9 | 0.950 |
| Fe₂O₃ | 0.4 | 0.077 |
| TiO₂ | 0.4 | 0.155 |
| Na₂O | 0.1 | 0.050 |
- Equivalent weight
- 3086.36
- Fired weight
- 2756.12
- Loss on ignition
- 10.7%
The equivalent weight is the grams of German Kaolin (Bodmer Ton 539) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Kaolin dust; German washed kaolins usually contain some fine quartz. Avoid breathing the dust.
Use it in a recipe
Add German Kaolin (Bodmer Ton 539) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.