Potassium Oxide K2O

Alkali Flux Unit 6 Topic 2
Oxide Qualities

Powerful flux - very high expansion - melts at Cone 8-9


  • A very vigorous flux; acts in a similar way to sodium oxide but is different in chemical form and behaviour so that it cannot be substituted for sodium oxide except in small quantities. This is especially true where colours are concerned.
  • Encourages more brilliance than sodium oxide and may slightly extend the maturing firing range of the glaze.
  • Usually combined with Na2O and expressed as KNO or KNa2O in unity formula calculations.
  • Fuses at C.8-9.

Insoluble Sources

  • Feldspars (especially potash feldspars) for mid to high temperature range glazes.
  • Fritts - usually used in low temperature glazes.

Soluble Sources

Usually used in the creation of fritts.

  • Potassium Carbonate (pearl ash).

Colour Responses

  • Alkaline - noted for unusual & exciting colours.
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