The primary goal of the restoration was to expose the original surface in order to make the legend of the coin legible again. They are then digitized and presented on the KENOM online portal.
In addition, the coins were preserved to protect them from further corrosion and damage.

There were coins from all silver and copper alloys that were used in coinage. For the silver coins as well as the billon coins, chemical cleaning measures were primarily used, as mechanical cleaning damages their soft surface. In contrast, coins made of copper alloys were exposed almost exclusively mechanically.
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As the main agent for chemical cleaning of the surface, EDTA was used as 0.1-
Molar solution in dist. Water used. In addition, formic acid, sodium thiosulphate, sodium hydrogen sulphate and a few other chemicals were used.
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Numerous tools such as scalpels, triangular scrapers, fiberglass pens, burins as well as various brushes and rotating brushes were used for mechanical cleaning. Soft abrasives such as zinc or calcite powder were also used if required.

10% Paraloid B 72 in ethyl acetate was used for preservation. The coins made of copper alloys also received a protective layer made of 10% Cosmoloid H 80.

see here for more details
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