List of Flux Materials

Copyright © 1998 by Ian Currie

It is from this list that we will choose the Starting Point Glaze (No.31) With a little reading and experience we will be able to choose a flux set to suit a purpose. (We can actually do it at random with the possibility of very new and perhaps unreliable effects. ) The Rules of Thumb for Choosing a Flux Set summarises some characteristics for many of the more commonly used flux materials. A good text to consult for details of the properties of the fluxes listed below is Frank Hamer's "The Potter's Dictionary of Materials and Techniques".

The fluxes we choose will determine the set's temperature range. If we wish to get most of the set to melt at earthenware temperatures, it's advisable to have around 50% of a frit in Glaze No.31. There are many commercially available frits. It should be possible to obtain from the supplier a data sheet with an analysis and a brief description of the particular frit's main properties and uses.

The flux materials marked with * contain alumina and silica. We usually have at least one of these in our flux set. The flux materials marked with * are water soluble, and can therefore be absorbed into bisque, and can be difficult to control.

As well as being fluxes manganese carbonate and manganese dioxide are also colourants. They can be used up to 100% (in Glaze No.31), the higher range giving metallic glazes. The colourant iron oxide (not shown) is an active flux in reduction.


Amblygonite Li.AlF.PO4
Barium carbonate BaCO3
Barium sulphate BaSO4
Calcite CaCO3
Chalk CaCO3
Colemanite 2CaO.3B2O3.5H2O (variable)
Cornish stone* variable
Dolomite CaCO3.MgCO3
Feldspar (Potash)* K2O.Al2O3.6SiO2
Feldspar (Soda)* Na2O.Al2O3.6SiO2
Frits* various
Gerstley Borate Similar to Colemanite with some Na
Lepidolite* Li2F2.Al2O3.3SiO2
Limestone CaCO3
Lithium carbonate Li2CO3
Magnesium carbonate MgCO3
Magnesium carbonate (light) 3MgCO3.Mg(OH)2.3H2O
Manganese carbonate MnCO3
Manganese dioxide MnO2
Nepheline syenite* (K)NaO.Al2O3.4SiO2 (Approx)
Petalite* Li2O.Al2O3.8SiO2
Potassium carbonate (Pearl Ash)� K2CO3
Rock powder A large range of rocks make excellent flux materials, e.g. basalt, granite.*
Sodium carbonate (Soda Ash)� Na2CO3
Spodumene* Li2O.Al2O3.4SiO2
Strontium carbonate SrCO3
Talc 3MgO.4SiO2.H2O
Whiting CaCO3
Wollastonite CaO.SiO2
Wood Ash* (May contain solubles�) Variable, (often high in lime)
Zinc oxide ZnO