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!
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 . . .
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.
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.
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.
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!
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