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What a jar is and is not for

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What a collector actually uses So what is the jar for The second use is the valuable one Which makes the seal the specification And the plastic has to be one of the safe ones Bulk is not a lesser use What this property will not do And it will not pretend about clarity References

A stamp does not go in a jar. Saying so first makes the rest of this property useful.

What a collector actually uses

A stamp goes in a polyester mount or sleeve. A coin goes in a flip, a capsule or a 2x2. Those are the primary enclosures for this craft and they are not containers in the sense this catalog means.

So what is the jar for

Two things. Bulk, meaning an unsorted hoard, a jar of foreign change, a working accumulation of tokens. And an outer container holding properly enclosed items together with dry air around them.

The second use is the valuable one

Conservation guidance for metal is clear that the enemy is moisture and pollutants, and that the answer is a dry microclimate maintained with a desiccant. A sealed jar is exactly a microclimate, and it is far easier to maintain than a whole room.

Which makes the seal the specification

Not the clarity, not the shape. A jar that does not hold its atmosphere is a dust cover. The shelf carries 63 closures with an induction-seal liner and 42 with F217, and that is where the decision lives.

And the plastic has to be one of the safe ones

Polyester, polyethylene and polypropylene are the plastics conservation guidance names as suitable. PET is polyester, so 145 of the 146 containers on this shelf are a suitable material and the last is glass.

Bulk is not a lesser use

Most collections contain a great deal of material that is not individually valuable and still deserves not to corrode. A sealed PP jar with a desiccant is a better home for three kilograms of mixed copper than a cardboard box, by a wide margin.

What this property will not do

Tell you how to clean a coin, or whether to. Cleaning is where collections get destroyed, it is contested among people who know far more than a packaging catalog, and it has nothing to do with the container.

And it will not pretend about clarity

The archetype for this group says clarity matters more than anything else. 35 of the 146 containers are clear. That is a real gap between what the craft wants and what the shelf holds, and the containers section says so plainly.

References

Library of Congress, Care, Handling and Storage of Photographs: "Suitable plastic enclosures are made of uncoated polyester, polyethylene, and polypropylene." On standards: "To be considered photo-safe, storage materials must pass the physical and chemical requirements outlined in ISO 18902 including passing the Photographic Activity Test (PAT)." And on humidity: "Photographic emulsions may stick to plastic enclosures if they are exposed to high RH, especially above 70% RH." loc.gov

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.