If the MgO content
of our example formula in column A
is removed then effectively our glaze would have less flux in relation
to the alumina and silica content. which would mean that our glaze
would not melt as much if fired to the same temperature.
The formula
in column C with it's higher Al2O3 and SiO2 values reflects
this.
It has been
created by finding the new total for the flux oxides without the
MgO i.e. 0.8.
This value is
then divided into all of the remaining values in the formula.
e.g.
K2O .....0.2
divided by 0.8 = 0.25
Na2O... 0.1 divided by 0.8 = 0.125
CaO......0.5 divided by 0.8 = 0.625
Al2O3...0.4 divided by 0.8 = 0.500
SiO2.....2.6 divided by 0.8 = 3.25
