The objects

Coins and tokens

On this page8

Weight is the first constraint Which argues for small jars They abrade each other Copper is the reactive one Silver tarnishes from sulphur, not water Clear or opaque Label the outside, always References

Coins are heavy, hard and chemically fussy, which is an unusual combination for a container.

Weight is the first constraint

A jar of coins is dense. A 250 mL jar filled with copper is far heavier than the same jar of almost anything else this catalog holds, which reaches the closure, the shelf it sits on and the box it ships in.

Which argues for small jars

The shelf runs 6 to 250 mL with a median of 118. For coins that is the right end of the range: several small jars sorted by type beat one large jar of everything, for weight and for sorting.

They abrade each other

Loose coins in a jar move, and movement on uncirculated surfaces is damage. For anything above common circulated condition, individual enclosure first and the jar as the outer layer.

Copper is the reactive one

It responds to humidity, to acids and to handling oils. Below 35 percent RH in a sealed jar with a desiccant is genuinely protective, and it is the simplest intervention available.

Silver tarnishes from sulphur, not water

Which is a different problem with a different answer. Keep paper, board, rubber and doubtful adhesives out of the same sealed space, and the tarnish rate drops without the humidity changing at all.

Clear or opaque

The archetype says clarity matters most. For coins there is a real case the other way: light drives some surface changes, and 23 black and 15 amber containers on this shelf are doing something a clear jar does not.

Label the outside, always

What is in it, when sealed, when the desiccant was changed. A jar you have to open to identify is a jar whose atmosphere you keep replacing with the room.

References

National Park Service, Conserve O Gram, on the storage of metal objects: metals corrode in the presence of moisture and pollutants and should be housed below 35 percent relative humidity, stabilised in a dry microclimate using a desiccant such as silica gel. Deteriorating plastics emit acidic vapours that corrode metal, which is why a metal coupon is used to detect an off-gassing plastic. nps.gov

The Davis Pack Supply catalog, measured 18 October 2026. The numismatic and philatelic shelf is 391 rows: 146 containers and 245 closures. 81 PET, 64 PP and 1 glass, from 6 to 250 mL with a median of 118. Zero PVC. By colour 39 white, 35 clear, 23 black, 15 amber, 15 natural and 8 blue. Necks 70-400 at 113, 89-400 at 93 and 58-400 at 66.

Written from Library of Congress and NARA preservation guidance and from National Park Service Conserve O Gram material, and from the catalog as it stood on 18 October 2026. Conservation advice for a specific object is a job for a conservator; nothing here is a substitute for one, and a valuable or unusual item deserves that conversation rather than a jar.