Throw a jar and matching lid
The moment of truth: does the lid actually fit?
The process
- Throw a jar with a clean lid gallery
- Measure the gallery with calipers
- Throw a lid that matches: the flange should sit into the gallery with minimal gap
- Let both reach leather hard and test the fit
Success criteria
- The lid drops into the gallery without forcing
- It doesn't wobble or rattle
- It spins freely when placed (not wedged tight)
- It looks intentional, not gappy, not jammed
If it doesn't fit
- Too loose: the lid shrank more (was drier when thrown). Try leaving the lid slightly larger.
- Too tight: the lid is too big. Note the difference and adjust next time.
Keep notes on your measurements. You'll develop a personal "fudge factor" over time.