Conservation Showcase: Poland 1788 4 Groschen

Posted on 9/2/2011

A recent example from our conservation laboratory.

BEFORE CONSERVATION
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AFTER CONSERVATION
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At first glance, some coins may appear to be beyond help. The red residues and bright blue/green raised corrosion spots on the surface of this 1788 4 Groschen of Poland look at first as though the coin has been corroded away and suffered serious irreversible damage. The NCS conservators do, however, have a few techniques up their sleeves in dealing with this kind of issue.

Careful conservation removed both the thick red residues and the blue/green corrosion spots. Often residues like this have at least some adverse affect on the surfaces underneath. It is often a question in the conservator’s mind exactly how a coin such as this may come out. The surfaces underneath on this coin were luckily free from damage allowing for standard numeric grading with NGC. The large parallel scratches on the surface are not damage, but lines left by combination of the manufacture of the planchet and a less than full strike.

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