Closures and sizes
Updated
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Sealed, or open for display
A dome lid is for a jar meant to be looked at and opened often; an induction-sealed closure is for a specimen being protected from humidity for years. Those are different jobs and the shelf serves both: 21 dome lids and 64 HIS liners.
When sealing matters
For anything pyritized, anything with soluble salts, and anything you intend to keep rather than handle. Dry air is the conservation measure and a bonded membrane holds it better than a compressed gasket does.
When it does not
A tooth or a well-mineralized invertebrate in a stable room is not under chemical attack, and a sealed jar adds nothing except a barrier to handling. Not every fossil needs the full treatment.
Sizes run 50 to 500 mL
Which is enough range to match a jar to a specimen rather than part filling a standard one. A snug jar looks better, protects better and stores better, and on this shelf it is actually achievable.
Wide necks across the range
70-400 at 38 containers, 89-400 at 34 and 58-400 at 29. The specimen has to go in and come out without touching the wall, so neck width is a conservation specification and not a convenience.
Standardize where the collection is a series
A run of trilobites or a teaching set benefits from one jar and one closure: it stores evenly, labels consistently and costs less. Mixed sizes suit a display of unlike specimens.
And leave room for the mount and the card
The specimen is not the only thing in the jar. A mount, inert padding and a provenance card all take space, and a jar chosen on the specimen alone ends up too small.