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More Technical Information
| Adult Classes |
Clay and Glazes for the Potter by Daniel Rhodes is the potter's bible of
technical information - a must read if you want to be a serious potter. If you
have questions about oxidation, reduction, how glazes work, want to
formulate your own clay and glazes and want to understand different kinds
of clays and glazes, then buy this book and read it!
technical information - a must read if you want to be a serious potter. If you
have questions about oxidation, reduction, how glazes work, want to
formulate your own clay and glazes and want to understand different kinds
of clays and glazes, then buy this book and read it!
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produce.
Glazes: Glazes are similar to clays in their chemical composition but
have more fluxes. A flux is something that causes things to melt at a lower
temperature. The fluxes in glazes are things like calcium, sodium,and
potassium and are sourced from things like lime, whiting, feldspar and
talc. They flux the alumina and silica in the glazes and cause the glaze to
melt into a glass and fuse to the pot's surface. Metallic oxides like red iron
oxide, copper carbonate, cobalt carbonate, rutile and titanium dioxide
give glazes their color. When the glaze gets hot in the kiln and melts,
chemical reactions take place. The heat, atmosphere in the kiln, metallic
oxides and other glaze materials all affect the color and look of the fired
glaze.
Firing: Firing can be divided into high or low temperature firing and
oxidation or reduction. Energy sources are wood, gas, oil and electricity.
Low temperature firings are done from 1200 to 1900 degrees Fahrenheit.
High temperature firing is between 2200 and 2500 degrees F. Electric
kilns produce an oxidizing atmosphere. Kilns that burn fuel may be fired in
oxidation or reduction. To fire a kiln in reduction, you need to starve the
fire of oxygen so you get a smoky fire. A smoky fire has incomplete
combustion and the smoke contains carbon monoxide and unburned
carbon. Reduction firing affects the colors of the glazes.
The temperature and atmosphere you fire in will have a big effect on the
color and feel of your glazes and clays.
Low fired pots are porous and will absorb liquid and foods. They can be
used on an open flame for cooking and were used that way by primitive
people. High fired pots are strong, hard and nonabsorbent. They are
subject to thermal shock and will crack if used on a stove top, but are
good for oven use and food storage.
Glazes: Glazes are similar to clays in their chemical composition but
have more fluxes. A flux is something that causes things to melt at a lower
temperature. The fluxes in glazes are things like calcium, sodium,and
potassium and are sourced from things like lime, whiting, feldspar and
talc. They flux the alumina and silica in the glazes and cause the glaze to
melt into a glass and fuse to the pot's surface. Metallic oxides like red iron
oxide, copper carbonate, cobalt carbonate, rutile and titanium dioxide
give glazes their color. When the glaze gets hot in the kiln and melts,
chemical reactions take place. The heat, atmosphere in the kiln, metallic
oxides and other glaze materials all affect the color and look of the fired
glaze.
Firing: Firing can be divided into high or low temperature firing and
oxidation or reduction. Energy sources are wood, gas, oil and electricity.
Low temperature firings are done from 1200 to 1900 degrees Fahrenheit.
High temperature firing is between 2200 and 2500 degrees F. Electric
kilns produce an oxidizing atmosphere. Kilns that burn fuel may be fired in
oxidation or reduction. To fire a kiln in reduction, you need to starve the
fire of oxygen so you get a smoky fire. A smoky fire has incomplete
combustion and the smoke contains carbon monoxide and unburned
carbon. Reduction firing affects the colors of the glazes.
The temperature and atmosphere you fire in will have a big effect on the
color and feel of your glazes and clays.
Low fired pots are porous and will absorb liquid and foods. They can be
used on an open flame for cooking and were used that way by primitive
people. High fired pots are strong, hard and nonabsorbent. They are
subject to thermal shock and will crack if used on a stove top, but are
good for oven use and food storage.