|Monthly Tech-Tip |
Alternate Names: Lime Spar, Lime Feldspar, Ca-Feldspar
Feldspars are roughly divided into lithium, potash, soda, and calcium according the to fluxing oxide that predominates (theoretical formulae for each type are not found in nature). Calcium feldspars are not common and never near theoretical. Thus even if the CaO does not predominate over the K2O and Na2O it may still be labeled a Ca-Feldspar if there is an appreciable amount.
Feldspars are abundant and varied in nature. They contain small amounts of quartz (while nepheline syenite does not).
A plagioclase feldspar.
Anorthite info at webmineral.com
In ceramics, feldspars are used in glazes and clay bodies. They vitrify stonewares and porcelains. They supply KNaO flux to glazes to help them melt.
Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
The most common source of fluxes for high and medium temperature glazes and bodies.
|Oxides||CaO - Calcium Oxide, Calcia|
|Frit Softening Point||1550C|
|Density (Specific Gravity)||2.7-2.8|
|By Tony Hansen|
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