Preserving the Unique 1993 New Zealand $2 Coin: A Conservationist’s Guide

Historical Significance

As a conservationist, I’ve witnessed far too many valuable pieces ruined by improper cleaning or storage. The 1993 New Zealand $2 coin, featuring the Kingfisher, represents a fascinating intersection of numismatic history and modern minting techniques. This coin deserves proper preservation to maintain its unique characteristics for future generations.

Understanding the Alloy Composition

Before discussing preservation methods, it’s crucial to understand what we’re working with. The 1993 New Zealand $2 coin is made from aluminum-bronze, not bronze-coated aluminum as some sources incorrectly state. This alloy consists of 92% copper, 6% aluminum, and 2% nickel – the same composition used in Australian $1 and $2 coins.

Unlike plated coins such as Canadian loonies or clad American golden dollars, this coin is solid alloy throughout. The distinctive golden color comes from the alloy composition itself, not from any coating or plating process.

The Toning Phenomenon

One of the most distinctive features of this coin is its two-tone appearance, particularly noticeable along high points and edges. This isn’t damage or improper coating – it’s natural oxidation of the aluminum-bronze alloy. The aluminum content in the alloy oxidizes differently than pure copper, creating those characteristic lighter highlights.

Many collectors mistake this toning for damage or improper minting. However, this oxidation pattern is completely normal for aluminum-bronze coins and actually helps authenticate the piece. The security edge with its distinctive ribbed center stripe may also influence how oxidation patterns develop along the coin’s perimeter.

Proper Storage Solutions

Avoiding PVC Damage

The most critical preservation concern is protecting against PVC (polyvinyl chloride) damage. PVC is commonly found in older plastic coin flips and holders. When exposed to heat and humidity, PVC can break down and release acidic gases that cause irreversible green slime damage to coins.

For the 1993 New Zealand $2 coin, use only PVC-free holders. Look for products specifically labeled as “PVC-free” or made from materials like polyethylene or Mylar. These materials won’t react with the aluminum-bronze alloy or accelerate oxidation in harmful ways.

Choosing the Right Holders

Given the coin’s unique edge design, standard 2×2 holders may not provide adequate protection. Consider these options:

• Air-tite capsules designed for $2 coins
• Custom-sized flips that accommodate the security edge
• Slabbing services for particularly valuable specimens

The security edge, while historically interesting, can be vulnerable to nicks and scratches if not properly protected. A rigid holder that prevents the edge from contacting other coins is essential.

To Clean or Not to Clean

This is perhaps the most critical preservation decision. My strong recommendation: do not clean this coin.

The natural oxidation pattern is part of the coin’s character and authenticity. Any cleaning attempt risks:

• Removing the natural toning that helps authenticate the piece
• Creating microscopic scratches that reduce eye appeal
• Potentially damaging the security edge details
• Reducing the coin’s value to collectors who prefer original surfaces

If the coin has been contaminated with substances that could cause long-term damage (like food residue or harsh chemicals), consult a professional conservationist rather than attempting home cleaning methods.

Environmental Considerations

Temperature and Humidity Control

Aluminum-bronze coins are relatively stable, but extreme environmental conditions can accelerate unwanted reactions. Store your 1993 New Zealand $2 coin in an environment with:

• Consistent temperature (ideally 65-70°F)
• Relative humidity between 40-50%
• Protection from direct sunlight
• Minimal exposure to air pollutants

Handling Precautions

Always handle the coin by its edges, never touching the surfaces with bare fingers. The oils and acids on human skin can accelerate toning and potentially cause spots. Use cotton gloves when examining the coin, and work over a soft surface to prevent damage if dropped.

Documentation and Authentication

Given the variations in this coin’s appearance and the existence of both regular and proof versions, proper documentation is essential for preservation. Keep records of:

• The specific variety (KM#87 or KM#87.a)
• Any distinguishing characteristics or anomalies
• Original packaging if preserved
• Provenance information if available

Photograph the coin periodically to document its condition over time. This creates a valuable record for future owners and helps track any changes in the coin’s appearance.

Long-term Preservation Strategy

For collectors who view this coin as part of a long-term collection, consider these additional preservation steps:

Create a controlled storage environment using archival-quality materials. Store coins in a dedicated cabinet or safe that protects against environmental fluctuations. Consider using silica gel packets to maintain optimal humidity levels within storage containers.

Regularly inspect your collection for signs of environmental damage or PVC residue. Early detection of potential problems can prevent irreversible damage to valuable pieces.

Conclusion

The 1993 New Zealand $2 Kingfisher coin represents an interesting chapter in modern numismatics. Its unique aluminum-bronze composition, security edge design, and natural toning characteristics make it a fascinating piece for collectors and historians alike.

By understanding the coin’s materials and following proper preservation techniques, you can ensure this piece remains in excellent condition for future generations to study and appreciate. Remember that sometimes the best preservation technique is simply to leave a coin alone – the natural aging process of aluminum-bronze creates a unique patina that tells the story of the coin’s journey through time.

Whether you’re a serious collector or simply someone who appreciates the historical significance of this unusual coin, proper preservation ensures that its story continues to be told accurately and beautifully for years to come.

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