The chemistry of ceramic glazes are normally expressed as formulas. A unity formula has been retotaled to make the numbers of flux oxides total one.
A "unity formula" is just a formula that has been retotaled so that the RO group of oxides totals one. This is also called a Seger formula and this standard provides one basis for comparing glazes. The three column format of expressing a formula was first used by Hermann Seger. Here is how we would recalculate a raw formula to a flux unity:
Oxides Formula Formula
K2O 0.6 / 2.2 = 0.27
CaO 1.3 / 2.2 = 0.59
MgO 0.2 / 2.2 = 0.09
ZnO 0.1 / 2.2 = 0.05
Flux Total 2.2 1.0
Al2O3 0.9 / 2.2 = 0.41
SiO2 9.0 / 2.2 = 4.09
Mineral sources of oxides impose their own melting patterns and when one is substituted for another to supply an oxide a different system with its own relative chemistry is entered. An extreme example of this would be to source Al2O3 to a glaze using calcined alumina instead of kaolin. Although the formula may be exactly the same, the fired result would be completely different because very little of the alumina would dissolve into the glaze melt. At the opposite extreme, a different frit could be used to supply a set of oxides (while maintaining the overall chemistry of the glaze) and the fired result would be much more chemically predictable. Why? Because the readily and release their oxides the the melt.
Mole% is a way of expressing the oxide formula of a fired glaze or glass. It is a preferred over the formula by many technicians who use glaze or glass chemistry.
In ceramics, raw material chemistry is expressed as analyses. This is in contrast to fired glaze chemistries which are expressed as formulas.
Loss on Ignition is a number that appears on the data sheets of ceramic materials. It refers to the amount of weight the material loses as it decomposes to release water vapor and various gases during firing.
In ceramics, the chemistry of a glazes are expressed as formulas of oxides. There are direct links between the oxide chemistry and the fired physical properties.
Glaze chemistry is the study of how the oxide chemistry of glazes relates to the way they fire. It accounts for color, surface, hardness, texturem, melting temperature, thermal expansion, etc.
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Part of changing your viewpoint of glazes, from a collection of materials to a collection of oxides, is learning what a formula and analysis are, how conversion between the two is done and how unity and LOI impact this.
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INSIGHT enables you to enter material analyses as recipes as a first step to inserting them into the materials database. Imposing an LOI and understanding how to set unity and its connection for formula weight are important concepts.