Micrograph 655 and full record
- Micrograph no
- 655
- Brief description
- Small ceramic pot showing centimetre scale crystals within the glaze
- Keywords
- ceramic , crystalline glaze, devitrification , willemite
- Categories
- Ceramic
- System
- Soda-lime-silica glaze
- Composition
- Soda-lime-silica glaze containing zinc oxide 25, cobalt oxide 0.5 (wt%)
- Standard codes
- Reaction
- Processing
- See Further information
- Applications
- Sample preparation
- Technique
- Photography (no microscope)
- Length bar
- 5 mm
- Further information
- Careful heat treatment of the glaze produces a very small number of willemite (zinc orthosilicate, Zn2SiO4) nuclei which can grow to centimetre dimensions over the course of a few hours at a suitably high temperature. Cobalt in the glaze composition segregates preferentially to the willemite crystals, colouring them blue.
- Contributor
- Dr K M Knowles
- Organisation
- Department of Materials Science and Metallurgy, University of Cambridge
- Date
- 04/11/02
- Licence for re-use
- Attribution-NonCommercial-ShareAlike 4.0 International
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