My problem is between a lovely Buttercup Yellow glaze and Laguna/Miller ^6 porcelain. Sometimes the glaze, when fired, contains white bumps and clumps like scattered small and medium curds of cottage cheese, irregularly spaced on interior and exterior of a piece. This was found most of all on a bowl with thin glaze, but on pieces with thicker glaze there are occasional white spots. One of these spots has a tiny crater, indicating what exactly I don't know.
The glaze recipe includes EPK, Frit 3195, Neph Sy, Silica, Wollastonite, Bentonite, and Rutile.
On Laguna brown ^6 clay, the glaze is perfect, with no bumps. This is why I think there may be an interaction between the porcelain clay and glaze.
Thanks in advance for any helpful information.