What changes could be made to lower the maturing range of a glaze?

Unit 7 Topic 5
Using Unity Formula

To lower the maturing range, the SiO2 value in the unity formula might be reduced together with the Al2O3 value so that the ratio between the two remains constant.
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Changing Sandy's Clear from C.12 to C.10 by reducing stabiliser and glass-former content.

The change could be achieved by taking out some of the alumina and silica source material in a recipe (i.e. clay & silica) while monitoring the changes as reflected in the unity formula. This trial and error process can, however, be a time consuming one.

A more efficient method might be to work directly with the unity formula.

The limits data shows that the difference between the SiO2 values for C.10 and those for C.12 is about 0.625 mols.

The maturing temperature for Sandy's Clear could be lowered by reducing the SiO2 level to 3.75.

If the Al2O3 is also reduced so that the original Al : Si ratio (8.83) is approximately maintained then we preserve the balances such that the texture should remain nearly the same.

Sandy's Clear

Oxide
Mol. Parts
New Formula
KNO
CaO
MgO
0.20
0.54
0.26
0.20
0.54
0.26
Al2O3
0.50 - 0.075 =
0.425
SiO2
4.38 - 0.660 =
3.72
Al : Si
Expan.
8.76
8.18
8.76

Al2O3 and SiO2 values are reduced such that
the Al : Si ratio stays approximately the same.

After the changes are made to the unity formula the formula can be converted back to a recipe using formula-to-recipe processes in glaze software.
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