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The coins are removed from electrolysis and rinsed thoroughly in fresh water.
Nitric acid, at a 5% concentration is poured into individual cups holding the coins.
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The nitric acid acts as a bleaching agent. The coin remains in this solution for
approximately 15 minutes.
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Following the Nitric acid bath, the coins are rinsed and brushed with
baking soda and water.
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The baking soda has a two-fold effect on the coins, it neutralizes any remnants
of the nitric acid and acts as a light abrasive/polish for the silver.
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Coin Cleaning Photos: Step Four
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Every artifact that comes into the lab is assigned a tag number on the boat
upon recovery. It is vitally important that this tag number remains with the
artifact-this is our only way of assuring provenence. John outlines each coin
and records its tag number so that they may be matched up following polishing.
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The coins are placed in a jewelry tumbler with stainless steel shot and burnishing
compound.
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John places the coins into the tumbler.
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The coins remain in the tumbler for approximately 15 to 20 minutes.
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The coins are removed from the tumbler and rinsed in fresh water, then matched
up with the outlines and re-united with their unique tag numbers.
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The final step in the conservation process is to weight each coin and take a post
conservation photo of the obverse and reverse side of the coin. This information
is then entered into the Corporate Database, and made available to the public the
following day.
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