Clay notes
The slow dry
A newly thrown bowl can look ready long before its foot is. The rim is thin and exposed, while the base stays against the board. If the rim stiffens first, the two parts no longer shrink at the same rate.
Keep the first comparison small
Cut two tiles from the same slab. Leave one out and loosely cover the other. Check both at the same times and record changes at the corners and along the middle. Use the results to guide when you uncover larger pieces in the same room.
Notice the underside
Once a bowl is firm enough to handle, turn it over on a padded board for a short period. If the underside feels cooler or looks darker than the rim, give it time under a loose cover before moving it to the drying shelf.