NCS Conservation: Seeing Green?

Numismatic Conservation Services™ (NCS®) uses a variety of proprietary techniques to remove harmful contaminants, stabilize and protect a coin's surfaces and, in many cases, improve a coin's eye appeal. After coins are conserved by NCS, they are seamlessly transferred to Numismatic Guaranty Company® (NGC®), an independent affiliate of NCS, for grading and encapsulation.

Below are a few highlights of coins that were recently conserved by NCS and graded by NGC.

The use of lesser quality holders, such as those containing PVC and those that allow ambient air to circulate freely can cause the surfaces of a coin to go from bright and reflective to dull or green, which can lead to permanent surface changes. This silver Switzerland 1859 5 Franken was recently submitted for NCS conservation to address the hazy green residues that had developed particularly on the reverse.

The opaque pale green residues seen over the shield and lions are indicative of a coin that has been stored in a coin holder containing PVC. The conservators at NCS have developed special techniques to remove these kinds of residues without damage to the surfaces underneath. Following careful conservation work, this important Swiss coin was free of damaging residues and retains a mild tone fitting a coin of its age. This coin went on to grade well with NGC.

Switzerland 1859 5 Franken Before conservation Click images to enlarge.

Switzerland 1859 5 Franken After conservation Click images to enlarge.

While poor quality coin holders can create very unattractive and potentially damaging residues, some residues develop through other unknown causes. This large silver 1596 Hungary Taler issued in Transylvania was submitted to NCS with a heavy raised residue encrusted into the ridges of the design and legends. This kind of residue presents unique challenges for the conservator. Specific techniques were able to remove the heavy encrustation from the recesses of the design while leaving the coin with a pleasant color appropriate for a circulated 16th century silver piece. Following careful conservation this coin was able to grade numerically with NGC.

Hungary 1596 Taler Before conservation Click images to enlarge.

Hungary 1596 Taler After conservation Click images to enlarge.

Long-term storage in soft flips that contain PVC can lead to disastrous results on the surface of any coin held inside. This Silver 1925 Germany 3 Mark Rhineland commemorative was submitted to NCS to remove pale green residues that had formed uniformly over both sides of the coin. The NCS conservators are well adept at removing residues such as this and were able to remove all traces safely, leaving a bright white silver surface. This popular German coin was able to grade well with NGC.

Germany 1925 3 Mark Rhineland Commemorative Before conservation Click images to enlarge.

Germany 1925 3 Mark Rhineland Commemorative After conservation Click images to enlarge.

For more information about NCS, visit NGCcoin.com/NCS.

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