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Instructions for Uncleaned Coins Print E-mail


Teachers:  Instructions for Preparing Uncleaned Coins

Some ancient coins are in the state in which they came from the soil--i.e. they still have dirt and residue on them.  You  will want to put these coins into a distilled water soak one to two weeks before your students begin work.  You may want to pass them around the room first so that your students get to feel the ancient dirt for themselves and begin anticipating the attribution project!  


Soaking coins in distilled water is a good way to make them easier to prepare for attribution.  The ions of distilled water (hungry for minerals!) bond with the particles attached to the coin which in turn loosens the dirt.   This is the process described below.  (Some people prefer to soak their coins in olive oil, but others have found that encrusted coins may become more difficult to clean and may even turn a darker color.)


Students should . . .

Step 1:  Brush the coins using a toothbrush, water, and dishwashing soap (a mild one, such as Dawn). Rinse the coin thoroughly.  Any soap remaining on the coin will reduce the effectiveness of later distilled water soakings and can cause a white film to develop on the coin while soaking.  Sometimes this first step alone can reveal enough detail to attribute a coin.


Step 2:  Next comes the distilled water soak. Make sure that there are not too many coins in the container (plastic or glass--a good clean baby food jar or prescription bottle does the trick ) because too many free ions will dilute the power of the water. Each student can have his/her own container.  Film cannisters work well for this.


Step 3:  Change the water frequently if not daily. If the water becomes cloudy or discolored with bits of dirt in it, then it is overdue for a distilled water change.


Step 4:  Every couple of days, remove the coins and give them another toothbrush scrubbing.  Some people prefer using denture brushes, as they are harder and remove more than normal brushes. Rinse the coin thoroughly. This is where a fine mesh strainer comes in handy!


Silver or silvered coins, (if there are any in your lot!!!) should soak by themselves in individual containers. Apparently they don't get along with the other coins. Monitor them closely! 


Students should not remove the patina from a coin when clearing away the dirt and deposits.  It should NOT look like a shiny new copper penny!  When the coin is clear enough to attribute, tell students they are done with the preparation stage.  Further preparation instructions available at


  http://groups.yahoo.com/group/ACEhelp/ ("Bookmarks" section)