If you have a damp box, now is the time. Make sure the damp box plaster is wet, then spritz your bowls and put them inside. Hopefully they will reabsorb moisture from the wet plaster and rehydrate. They key will be to rehydrate slowly and evenly.
We found a quick way to make these... The Container Store sell water tight trunks, sealed with a nice gasket. We poured a 1.5" thick plaster slab in the bottom, cleaned it all up real nice after the plaster set up, spray water on the plaster so that it remains saturated, but not overly so such that water is displaced from the plaster. If it pools on the plaster it's saturated, just wipe up the pool before placing your wares inside.
Place your dry wares into the bin, seal it, forget it, in a week's time it's like trimming butter. Same principle that Chris mentions above, only a nice sealed container you can use over and over again. And, they are designed to stack too, they sort of interlock. We've stacked them 6 high no problem, and put them on mover's dollies so they can be repositioned to different stations as needed. And, they have holes on the lids for locks, when it's not freezing we can push them out of the studio and into a shed on the deck.