Measure a lid gallery with calipers

Lids require precision. Eyeballing doesn't work. You need calipers.

The exercise

1. Throw a small jar with a lid gallery (a recessed ledge at the rim, about 5 mm wide and 5 mm deep)
2. Let it firm enough to measure without deforming
3. Open your calipers and measure the inner diameter of the gallery
4. Record that number: this is your lid target

Important

• Clay shrinks when it dries and again when it fires
• Both the lid and the jar shrink at the same rate (same clay body)
• So measure when both are at the same stage (both leather hard, or both bone dry)

First time?

Start with a wide jar (10+ cm opening). Smaller openings are harder to measure and less forgiving.