What goes wrong

The fluid evaporated

Updated October 2026

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What it looks like The liner is almost always the cause Induction seals change the problem Warm storage accelerates everything Top up, and record it Glass removes one variable Keep one jar as a control It is the commonest loss in a fluid collection References

Ethanol leaves through a marginal seal, and a specimen above the fluid line is a lost specimen.

What it looks like

A fluid level that has dropped, a specimen partly exposed and gone brittle or discolored, and sometimes crystalline residue at the neck. By the time it is visible the damage is usually done.

The liner is almost always the cause

Alcohol passes through, swells or dissolves several common liner materials. Of the 222 closures on this shelf, 61 carry an HIS induction-seal liner and 38 an F217, and which suits your preservative is a question for the supplier.

Induction seals change the problem

A bonded membrane is a much better barrier than a compressed gasket, and it needs a sealing machine. For a long-term collection that is a real argument for sealing rather than just capping.

Warm storage accelerates everything

An attic or a sunny room drives evaporation and expands the headspace. Cool, dark and stable is not a preference here, it is the difference between a decade and a few years.

Top up, and record it

A collection in fluid needs checking and topping up on a schedule, and the schedule is the actual conservation practice. A jar nobody has opened in ten years is not preserved, it is unmonitored.

Glass removes one variable

All 29 containers here are glass, so the wall is not permeating. That narrows the investigation to the closure, the liner and the storage, which is as it should be.

Keep one jar as a control

Filled with fluid and no specimen, sealed the same way, stored the same way, and weighed occasionally. It tells you the loss rate of your own closure choice without risking anything.

It is the commonest loss in a fluid collection

Not contamination and not breakage. Slow evaporation through an unsuitable liner, discovered years later, with the specimen already damaged. Spending on the closure is spending on the specimen, which is not how most people allocate a budget for a jar.

References

29 CFR 1910.1200, Hazard Communication, which sets what a shipped container of a hazardous chemical carries and requires a safety data sheet. law.cornell.edu

49 CFR 173.4, Small quantities for highway and rail. Class 3 and other listed materials are not subject to other requirements where the inner receptacle holds no more than 30 mL of liquid, is not liquid-full at 55 C, is glass, earthenware, metal or plastic of at least 0.2 mm, has any removable closure held securely with wire, tape or other positive means, and is packed with non-reactive absorbent able to take the entire contents inside a strong outer packaging, the whole demonstrated by prototype testing. law.cornell.edu

Written from federal statute and regulation, not from a collection room. Wildlife law is federal, state and sometimes tribal at once, and the Lacey Act makes a state or foreign violation a federal matter. Nothing here is advice on a particular specimen, and the permit questions belong to the Fish and Wildlife Service.