Digitalfire Ceramic Materials Database
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Alternate Names: Custer Spar
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This is one of the main feldspars used in the ceramic industry in North America, especially in the west. It is used in industries such as abrasives, sanitary ware, floor and wall tile, dinnerware, pottery, and electrical porcelain throughout the United States, Mexico and Canada. This ceramic grade high potash feldspar is available in crude, 200, 325 mesh and chip form.
Jan 2012: We were getting reports of a reduction in the potash content. Traditionally it has been reported as around 10% (as is shown in the chemistry given here, it is from their online data sheet dated 3/23/2005). However, analyses of many specimens over the past ten years (as provided to us by Ron Roy) suggests that around the year 2000 the K2O content dropped to about 7.5 (with no accompanying change in the Na2O). However, a melt flow test from Plainsman Clays using 2012 material demonstrates that melting is the same over the past year, it does not detect this possibly longer term trend. The chemical analysis of a load received in Nov 2013 reports 10.1 K2O, 3.1 Na2O and 0.1 Fe2O3 (which very closely matches their reported numbers).
Users should be vigilant to do sieve analysis testing to spot any iron bearing particles in the plus 100 mesh range.
Out Bound Links
K-Feldspar, Orthoclase, K Feldspar, Potassium Feldspar
These materials are specially defined for makers o...
This is the traditional Ron Roy materials file. He...
The decision about what materials to include in th...
Latin America and South America. We are working on...
Countries of Eastern Europe and former Soviet Unio...
All of Asia including Turkey, Russia, Indosnesia, ...
All of continental Africa. We are working on this ...
In Bound Links
G200 Feldspar, G200 Spar, G 200 Spar, G 200, G 200 Feldspar
MC 200-K Feldspar
A cone 8 comparative flow tests of Custer, G-200 and i-minerals high soda and high potassium feldspars. Notice how little the pure materials are moving (bottom), even though they are fired to cone 11. In addition, the sodium feldspar move better than the potassium ones. But feldspars do their real fluxing work when they can interact with other materials. Notice how well they flow with only 10% frit added (top), even though they are being fired three cones lower.
Melt flow test comparing Custer Feldspar from Feb/2012 (right) with Mar/2011 (80:20 mix of feldspar:Ferro frit 3134 has been used for a good flow at cone 10).
By Tony Hansen
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