Storing and preserving ancient coins safely
By Sébastien · · 6 min read
An ancient coin has crossed the centuries; yet it can degrade in a few months if poorly kept. Overzealous cleaning, aggressive plastics, humidity: a few mistakes are enough to ruin a patina or trigger corrosion. Here are the right reflexes. This article extends the guide cataloguing an ancient coin collection.
Rule no. 1: do not clean
This is the most damaging reflex. Rubbing, stripping or polishing an ancient coin destroys its patina — that stable layer formed over time — and can cause its value to drop dramatically. In case of dirt or active corrosion, it is better to consult a specialist than to improvise a cleaning.
Handling with care
Handling transfers salts and grease that attack the surface. A few simple rules:
- Hold the coin by the edge, never flat between your fingers.
- Use clean gloves (cotton or nitrile) for sensitive pieces.
- Handle over a soft surface to avoid impacts if the coin drops.
- Avoid speaking over coins during prolonged handling.
Choosing PVC-free materials
PVC is storage enemy no. 1: as it ages, it releases compounds that cause an irreversible greenish corrosion ("PVC disease"). Choose capsules, flips and trays that are PVC-free, in inert materials (polyester, polypropylene, archival-grade PET).
Controlling humidity
Humidity is the engine of corrosion, especially for bronze and billon. Aim for a dry, stable environment, away from sharp temperature swings. Silica gel in the cabinet helps absorb residual moisture; check it regularly.
Capsules and coin cabinets
For storage, individual capsules (PVC-free) protect against impacts and air, while a coin cabinet with felt-lined drawers (undyed felt) offers stable arrangement. The key: each piece isolated, immobile, in an inert material, in a dry place.
Documenting condition
Preservation and cataloguing go together: record each coin's condition in its file, with a reference photo. You will then detect any change (spot, corrosion) by comparing over time. Condition drives value — see valuing an ancient coin — and is an integral part of the catalogue.
In practice with AncientDesk
AncientDesk keeps each coin's condition, reference photos and record history, which helps monitor how preservation evolves over time — all locally. A question about a fragile piece? Feel free to contact us.
Frequently asked questions
Should I clean an ancient coin before storing it?
No. Cleaning destroys the patina and lowers the value. In case of active corrosion, consult a specialist rather than cleaning yourself. When in doubt, do not touch the surface.
Why avoid PVC materials?
Over time PVC releases compounds that cause irreversible greenish corrosion on coins. You need PVC-free capsules and flips, in inert materials such as polyester or polypropylene.
What storage conditions suit ancient coins?
A dry, stable environment away from temperature swings, each piece isolated in a PVC-free capsule or a felt-lined cabinet. Silica gel helps control humidity, especially for bronzes.
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