Preserving Your Shipwreck Treasure: A Conservator’s Guide to Long-Term Protection

Introduction: The Fragility of History

I’ve seen too many valuable pieces ruined by improper cleaning or storage. Here is how to keep this safe for the next generation.

The Science of Shipwreck Patina

When coins spend centuries underwater, they develop unique surface characteristics that tell their story. The toning on shipwreck coins isn’t just cosmetic—it’s a complex chemical record of their journey through time and water. Understanding this process is crucial for proper preservation.

Shipwreck coins typically exhibit several types of surface changes:

• Natural toning: The result of prolonged exposure to saltwater minerals
• Corrosion products: Often appearing as green or blue deposits on copper and bronze coins
• Mineral deposits: White or crystalline formations from evaporated seawater

The Dangers of Improper Cleaning

One of the most common mistakes I see is well-intentioned collectors attempting to “restore” their shipwreck coins to a shiny, new appearance. This is almost always a mistake that destroys value and historical integrity.

Never clean a shipwreck coin with abrasives, acids, or commercial coin cleaners. The patina is part of the coin’s history and value.

Cleaning can:

• Remove the distinctive shipwreck patina that collectors value
• Create microscopic scratches that accelerate future deterioration
• Remove important diagnostic features used to authenticate the coin
• Significantly reduce the coin’s market value

PVC Damage: The Silent Destroyer

Polyvinyl chloride (PVC) is found in many older coin holders and flips. When exposed to heat or humidity, PVC can break down and release acidic gases that cause irreversible damage to coins.

Signs of PVC damage include:

• Green, slimy deposits on the coin surface
• Clouding or discoloration of the holder itself
• A distinctive “plastic” smell when the holder is opened

Always store shipwreck coins in PVC-free holders made from materials like Mylar, polyethylene, or archival-quality plastics.

Proper Storage Solutions

The ideal storage environment for shipwreck coins maintains stable temperature and humidity levels while protecting against physical damage and environmental contaminants.

Temperature and Humidity Control

Shipwreck coins are particularly sensitive to environmental changes because they’ve already undergone significant chemical alteration. Store them in an environment with:

• Temperature between 65-70°F (18-21°C)
• Relative humidity between 45-55%
• Minimal temperature fluctuations

Physical Protection

Use appropriate holders that provide both physical protection and environmental isolation:

• Archival-quality coin capsules for individual pieces
• Acid-free coin albums for display
• Desiccant packets to control moisture in storage containers

When Professional Conservation is Necessary

While cleaning is generally discouraged, there are situations where professional conservation may be appropriate:

• Active corrosion that threatens the coin’s structural integrity
• Heavy encrustations that obscure important details
• Stabilization of unstable surfaces

Always consult with a professional conservator who specializes in numismatic materials before attempting any intervention.

Documentation and Provenance

Proper documentation is as important as physical preservation. Maintain records of:

• Purchase history and provenance
• Grading and authentication certificates
• Storage conditions and any conservation work
• Photographs documenting the coin’s condition over time

Insurance and Security

Shipwreck coins represent both historical significance and substantial monetary value. Ensure proper insurance coverage that specifically addresses numismatic collections, and implement appropriate security measures for your storage location.

Regular Monitoring

Even with proper storage, regular monitoring is essential. Check your collection every 3-6 months for signs of:

• Environmental damage
• Changes in toning or surface condition
• Issues with storage materials
• Pest activity in storage areas

Conclusion: Preserving History for Future Generations

Shipwreck coins are more than just collectibles—they’re tangible connections to maritime history and human stories of adventure, tragedy, and survival. By following proper preservation techniques, you’re not just protecting an investment; you’re safeguarding a piece of history for future generations to study and appreciate.

Remember: when in doubt about any aspect of preservation or conservation, consult with professionals who have experience with shipwreck artifacts. The cost of expert advice is always less than the cost of irreversible damage to a historical treasure.

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