Preserving PCI Slabbed Coins: A Conservationist’s Guide to Toning and Storage

Introduction: The Delicate Balance of Preservation

Over the years, I’ve witnessed too many valuable pieces ruined by improper cleaning or storage. Here’s how to keep your collection safe for the next generation.

Understanding PCI Holders and Their Unique Properties

The PCI (Professional Coin Grading Service) holders, originally designed and produced by Hallmark, have become a fascinating study in coin preservation. These holders emerged during a pivotal era when third-party grading was establishing itself in the numismatic marketplace. As forum member MrEureka noted, Hallmark was a legitimate grading firm formed by Lee Bellisario and prominent partners, including QDB (Q. David Bowers).

What makes these holders particularly interesting from a preservation standpoint is their tendency to produce distinctive toning patterns on the coins they contain. This toning, while sometimes aesthetically pleasing, can also progress to what collectors call “terminal toning”—a state where the toning becomes so dark and opaque that it obscures the coin’s details and significantly impacts its numismatic value.

The Hallmark Connection

It’s worth noting that while PCI coins often exhibit significant toning, forum discussions reveal that Hallmark slabs themselves rarely showed this same characteristic. This suggests that the toning issue may be related to changes in materials or manufacturing processes after Hallmark’s initial production. The exact cause remains a topic of speculation among collectors, with theories ranging from different insert materials to variations in the plastic composition of the slabs themselves.

Identifying Toning Patterns and Their Implications

The toning produced by PCI holders can range from subtle rainbow hues to deep, rich patinas. Some collectors actively seek out these toned specimens, appreciating the unique character they bring to a collection. However, the progression of toning is not always predictable or desirable.

Recognizing Terminal Toning

Terminal toning occurs when the toning process continues unchecked, eventually covering the coin’s surface in a dark, often blackish layer. This type of toning can be particularly problematic for coins that were originally designated as “100% White” by PCI—a designation that indicated the coin was completely untoned and bright white.

As one forum member humorously noted, PCI was “going out on a limb” with the “100% White” designation on their SE (Special Edition) coins, given the propensity of their holders to produce toning. This highlights the importance of understanding that even professionally graded coins in sealed holders can continue to change over time.

Proper Storage Solutions for PCI Slabbed Coins

When it comes to preserving PCI slabbed coins, collectors face a dilemma: maintain the historical integrity of the original holder or intervene to prevent further toning?

The Case for Original Holder Preservation

Many collectors value the historical significance of keeping coins in their original PCI holders. These holders represent a specific era in coin grading history and can themselves become collectible items. The slabs appear to be relatively resistant to scratching and wear, suggesting they may offer good protection against physical damage.

When to Consider Reholdering

However, if toning is progressing toward the terminal stage, reholdering may be necessary to preserve the coin’s detail and value. Forum member Connecticoin suggested moving a nicely toned Franklin half dollar into a PCGS holder to halt the toning process. This approach can be effective, though it does come with the risk of receiving a “Questionable Color” (QC) designation from the new grading service, as another member pointed out.

Preventing PVC Damage and Other Storage Hazards

While the PCI holders themselves don’t appear to pose a PVC (polyvinyl chloride) risk based on the condition of the slabs discussed in the forum, proper storage of the holders is still crucial. PVC damage typically occurs when coins are stored in soft plastic flips or other containers that contain this chemical, which can leach onto the coin’s surface and cause irreversible damage.

Best Practices for Holder Storage

To protect PCI slabbed coins:

• Store slabs in a cool, dry environment away from direct sunlight
• Use inert storage materials such as acid-free boxes or albums designed for slab storage
• Avoid stacking slabs too high to prevent pressure damage
• Maintain consistent temperature and humidity levels

To Clean or Not to Clean: The Conservationist’s Perspective

This question is particularly relevant for PCI slabbed coins that may have developed toning. From a conservationist standpoint, the answer is almost always: do not clean.

The Risks of Cleaning

Cleaning a coin, especially one that has developed toning in a PCI holder, can significantly reduce its value and historical authenticity. The toning patterns in these holders are part of the coin’s story and its journey through time. Attempting to remove this toning through cleaning can result in:

• Removal of the coin’s natural patina
• Creation of unnatural-looking surfaces
• Potential scratching or other physical damage
• Significant reduction in collector value

Professional Conservation Options

If a coin’s toning is truly problematic, professional conservation services may be an option. These experts can sometimes stabilize toning or make subtle improvements without the harsh effects of DIY cleaning methods. However, this should be considered a last resort and only undertaken after careful consideration of the coin’s value and historical significance.

Monitoring and Documentation

For collectors who choose to keep their coins in PCI holders despite toning concerns, regular monitoring is essential. Document the appearance of your coins with high-quality photographs, noting any changes in toning patterns over time. This documentation can be valuable for insurance purposes and for tracking the progression of toning.

Creating a Preservation Log

Consider maintaining a log for your PCI slabbed coins that includes:

• Date of acquisition
• Current grade and toning description
• Photographs from multiple angles
• Storage conditions (temperature, humidity)
• Any interventions or reholdering decisions

Conclusion: Balancing Preservation and Historical Integrity

The PCI holders represent a fascinating chapter in numismatic history, and the coins they contain tell stories not just of their minting, but of their journey through time in these distinctive slabs. As collectors and conservationists, our role is to preserve these stories while protecting the physical integrity of the coins themselves.

Whether you choose to maintain the original PCI holders or opt for reholdering to prevent further toning, the key is to make informed decisions based on the specific needs of each coin. By understanding the unique properties of these holders and implementing proper storage and monitoring techniques, we can ensure that these pieces of numismatic history remain preserved for future generations to study and appreciate.

Remember, every coin in your collection has a story to tell. Our job as conservators is to listen to those stories and protect them, allowing the coins to speak for themselves without the interference of well-meaning but potentially damaging interventions.

Related Resources

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