I'm desperately in need of a clear glaze that doesn't blister when  applied over a porcelain slipped surface that has been decorated with underglaze (either before or after bisquing).  My reading tells me its at least partially a problem with glaze viscosity - I think this is part of the problem since the blistering is worse at the top of the wall of a bowl and virtually non-existent in the bottom where the glaze is thicker. It also seems to correlate with areas where the porcelain slip is, as the exact same glaze on the outside of the bowl that has no slip is smooth and clear as a bell.

I've tried the Glossy Clear Liner Glaze from Master Cone 6 Glazes and Robin Hopper's Clear - both are blistering

Ideas????