Conservation Showcase: 1909-S $20
Posted on 7/19/2011
A recent example from our conservation laboratory.
Many types of residues are seen on similar types of coins over and over again. The heavy rusty red residue as seen on this 1909-S gold $20 is one of those such residues. Tenacious in its hold on the surface, this red would most certainly cause a coin to be rejected from grading with NGC.
The conservators at NCS have developed techniques to remove red residues such as this from the surface of gold coins. Each type of residue combines with each type of coinage metal to create unique challenges for the conservator. After carefully removing the unsightly red, the coin was left with an even pleasant look and was able to grade numerically with NGC.
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