may be expressed as a single value e.g. 10.32 or in the form
1 : 10.32 meaning that theoretically for every one molecule
of Al2O3 there
is 10.32 molecules of SiO2.
temperatures the Al2O3 : SiO2 ratio for clear glazes is in
the vicinity of 1 : 9.
Blue Celedon may therefore be close to a clear glaze with
perhaps a slight tendency to be opacified by the small excess
of SiO2 in relation to the alumina.