Coin Cleaning Process
 April 9, 2006 -- Ron Pierson
Coin Cleaning Photos: Step Three
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.
The nitric acid acts as a bleaching agent. The coin remains in this solution for approximately 15 minutes.
Following the Nitric acid bath, the coins are rinsed and brushed with baking soda and water.
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.
Coin Cleaning Photos: Step Four
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.
The coins are placed in a jewelry tumbler with stainless steel shot and burnishing compound.
John places the coins into the tumbler.
The coins remain in the tumbler for approximately 15 to 20 minutes.
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.
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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