Glaze troubles

We borrowed a dehumidifier from Christy's parents. It's really stepped up the pace of drying in the studio. Unfortunately as some of our pots finish drying we've noticed that the glazes don't shrink quite as much as we had thought they did. Why these problems did not show up during all the tests we did is a little bit of a mystery. You can see here a slight cracking of the glaze on the rim of this pitcher.Christy's flat ware got the worst of it, as you can see on the square platter on the left, the glaze has completly fallen off the rim.
It's an easy problem to solve and we've already added 2.5% more bentonite to all the glazes which should solve the problem. Certainly not all of the pots have been affected. Frustrating none the less. For the potters out there apperantly 30% ball clay and 5% bentonite isn't quite enough shrinkage in high ash glazes... who knew?
Joe