Wood Ash
Links to Other Materials
- Volcanic Ash - Alternative
- Applewood Ash - Related
- Oakwood Ash - Related
- Pine Wood Ash - Related
- Eucalyptus Ash - Related
- Hardwood Ash - Related
- Rice Husk Ash - Alternative
- Rice Straw Ash - Alternative
- Soft Wood Ash - Related
- Cache
Hazards
- Plant Ash
Miscellaneous
- Family: Flux Source
- Region: None
- Mined At: Unspecified
- Raw Mineral: No
- Generic: Yes
Notes
Wood ash has been used in glazes since primitive times. When wood is burned and the black ash is put into water the unburned carbon material floats and is discarded while the ash itself settles to the bottom. When dried to a powder this material can be quite light in color. When mixed with a clay and feldspar it assists melting and produces the classic variegated and often coveted ash glaze surfaces. Part of the attraction of ash glazes is that each type of ash has a very different chemistry and even ash from the same source is not consistent. People practicing this art thus are always seeking a 'vintage batch'.
Many books for potters deal with the subject of preparing and formulating ash glazes. Generally the key to success is to process a large batch of ash and use a minimum of it developing a recipe tuned to it. When the chemistry of the ash is unknown triaxial blending techniques with feldspar and clay are usually best to zero-in on a good mix (some people also mix ash and a low fire red clay). If the chemistry is known then you can compare the ash to target formulas for the temperature you work at and add materials to supply oxides that are absent or deficient (this in turn dilutes the ones that are in excess).
Since it takes a lot of wood to make a little ash it can be challenging to find a consistent source. In some areas wood fired pizza is popular, these places will have an ongoing supply of ash and you can predict its consistency by asking about their wood supply. Also, it is important that the wood not be too dirty since the dirt does not decompose, its small proportion in relation to the wood can be a large proportion related to the ash.
Linked Articles
Formulating Ash and Native-Material Glazes
How to have a volcanic ash analysed and them use ceramic chemistry to create a glaze that contains the maximum possible amount of the ash for the desired effect
URLs
- A good place to buy pottery books - www.axner.com
Authors
- Tony Hansen (Owner)
XML
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<notes>
<note>Wood ash has been used in glazes since primitive times. When wood is burned and the black ash is put into water the unburned carbon material floats and is discarded while the ash itself settles to the bottom. When dried to a powder this material can be quite light in color. When mixed with a clay and feldspar it assists melting and produces the classic variegated and often coveted ash glaze surfaces. Part of the attraction of ash glazes is that each type of ash has a very different chemistry and even ash from the same source is not consistent. People practicing this art thus are always seeking a \'vintage batch\'.
Many books for potters deal with the subject of preparing and formulating ash glazes. Generally the key to success is to process a large batch of ash and use a minimum of it developing a recipe tuned to it. When the chemistry of the ash is unknown triaxial blending techniques with feldspar and clay are usually best to zero-in on a good mix (some people also mix ash and a low fire red clay). If the chemistry is known then you can compare the ash to target formulas for the temperature you work at and add materials to supply oxides that are absent or deficient (this in turn dilutes the ones that are in excess).
Since it takes a lot of wood to make a little ash it can be challenging to find a consistent source. In some areas wood fired pizza is popular, these places will have an ongoing supply of ash and you can predict its consistency by asking about their wood supply. Also, it is important that the wood not be too dirty since the dirt does not decompose, its small proportion in relation to the wood can be a large proportion related to the ash.</note>
</notes>
</material>
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