|Monthly Tech-Tip |
Description: Potash Feldspar
No longer available. When looking for a substitute, note how high KNaO content in this. It is much higher than Minspar or Custer. G200 HP, although having a different ratio of K2O/Na2O shares the high KNaO content (and other oxides levels are very similar).
Feldspars are employed in glaze recipes as melters. So comparing their melt fluidities should be helpful in deciding if one can substitute for another (of course, if possible a soda predominant feldspar should be substituted for another soda spar). Feldspars don't melt alone at cone 6 (2200F) so we mixed each with 15% Ferro Frit 3195. Nepheline Syenite is obviously the champion melter here. Other similar ones can be spotted easily. In the end, degree of melt is a valid consideration in determining if one feldspar is a viable substitute for another in a recipe. Even if the feldspar you want to substitute does not melt as much a little frit can be added to the recipe to make up for the difference (e.g. even just 1 or 2%).
The most common source of fluxes for high and medium temperature glazes and bodies.
|By Tony Hansen|
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