NCS Conservation: Original Surfaces Shine after Residue Removal

Posted on 4/13/2021

Modern and vintage coins alike benefit from NCS conservation.

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 Corporation® (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.

Even very recently made modern coins can develop residues that are unattractive and potentially irreversibly damaging. This 2016 Proof struck Great Britain gold ½ Sovereign was recently submitted to NCS to address a thick opaque residue that had developed in a spotty fashion particularly on the reverse. How this residue came to be is likely a combined effort of improper storage and perhaps the materials used in original mint packaging.

Conservators at NCS have developed techniques to safely remove thick residues from the surface of modern Proof coins without damaging the mirrors underneath. This coin was able to grade very well with NGC following professional conservation.

Great Britain 2016 Gold 1/2 Sovereign
Before conservation
Click images to enlarge.

Great Britain 2016 Gold 1/2 Sovereign
After conservation
Click images to enlarge.

While residues can be unattractive, they can also lead to permanent damage. This 1854 Great Britain Penny was sent to the conservators at NCS to address an unattractive somewhat unusual green residue that had developed on predominantly the reverse. Heavy residues can form through poor storage as part of a collection as well as the result of circumstance long before the piece has numismatic value. A green residue is often an indicator of long-term storage in a coin holder containing PVC.

Luckily for this large British copper, the terrible green residue was able to be removed revealing a nice evenly colored slightly circulated copper Penny. Following conservation, this coin was able to grade with NGC.

Great Britain 1854 Penny
Before conservation
Click images to enlarge.

Great Britain 1854 Penny
After conservation
Click images to enlarge.

Thick heavy residue development is a cause for concern. Heavy residues often cause and hide permanent damage to a coin surface. This silver 1925 Poland 2 Zlote struck in London was submitted to NCS with a very thick multi-colored residue. Careful work is required to remove such advanced residues without damaging any of the original surface underneath. This Polish coin was able to be returned to a bright white state free of any residue that could damage the surface in long-term storage. After conservation, this coin was able to grade numerically with NGC.



Poland 1925 2 Zlote
Before conservation
Click images to enlarge.

Poland 1925 2 Zlote
After conservation
Click images to enlarge.

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


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