Conservation Showcase: 1928 D Dime
Posted on 12/21/2009
A recent example from our conservation laboratory.
Numismatic literature is full of references to the dangers long-term storage in PVC laden holders can cause. Storage in so-called soft holder or those containing the PVC plasticizer can cause problems no numismatist would like to see happen to a coin. The chemical plasticizer will leach out of the plastic in the holder creating a green film or sludge on the surface of a coin. If left alone, this green malady can cause corrosion into the surface of a coin.
This 1928 Denver Mint Dime was recently submitted to NCS demonstrating the typical signs of early PVC impairment. A pale green film has developed rather uniformly on the surface of this coin. The technicians at NCS were able to remove the residue from the surface of this Dime that had luckily been caught before corrosion had begun to take hold. This coin was able to grade numerically with NGC following the conservation.
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