for a clear glaze all oxides need to be dissolved and remain in
the glass matrix on cooling.
that are not clear either
oxides that were not dissolved or
oxides which precipitated out of the molten glass during the cooling
a fine pattern of gas bubbles trapped in the glass.
clear glaze balance will vary depending on the mix and level of
individual flux oxides in the glaze for the chosen firing temperature.
each flux group pattern and firing temperature there will be a certain
level of alumina and silica which will create clear glass providing
the flux oxide content is not excessive.