bronze and Romana
New Hope For Those Hopeless Coins
One of the most oft-asked questions by detectorists is, "How
do I clean the coins and tokens I find? Sometimes I donít know which
question is asked most: "How do I clean my coins?" or
"What do women really want?" Iíve been married for more
than 10 years, grew up in a household of sisters and dated women
extensively for an extended period of time, so naturally, I know
more about cleaning coins.
The best way to clean coins without damaging their value is, of
course, to have them cleaned by a professional coin dealer. If you
even think a coin or token might have any kind of value whatsoever,
have it evaluated. In some cases, even rubbing a coin lightly under
running water can mar the surface with tiny scratches. There are
some detectorists who say there are ways to home-clean coins and
have the evidence escape a professional coin dealer, but itís hard
to fool a truly professional numismatist. And there are some coin
dealers you just donít want to try to fool -- especially in my neighborhood,
where coin dealers have names like Maury The Fist. But the vast
majority of dug coins are worth only face value or less due to wear
from circulation, lack of rarity or environmental damage from moldering
in the ground for so long or being exposed to fertilizers, so they
arenít worth the professional cleaning expense. Still, you might
want to clean them up enough to at least read them for display or
adding to your collection, so the devaluation caused by anything
you could do at home would be no huge deal.
Iíve seen a lot of different home cleaning methods, from using
a steel brush to soaking coins in lemon juice. One of the gentlest
methods is to soak your finds in olive oil. You simply immerse the
coins in plain old olive oil (change the oil when it gets grungy-looking)
until the crud works itself loose. This can take anywhere from several
days to several months, depending on how crusty your find is. Not
everyone has this kind of time, but if you do (especially if you
want to preserve the fine green patina on copper objects and donít
mind yet another thing on a shelf catching dust), the olive oil
soak is the only ticket.
Another method I've seen is by building a home-made electrolysis
machine. This involves jerry-rigging an AC adapter for a small electrical
appliance (like a cassette tape player) by slicing off the end that's
plugged into the appliance and attaching alligator clips. One clip
is attached to the object to be cleaned, the other to a stainless
steel spoon or large bolt and dumped into a glass container containing
a salt water or baking soda and water solution. The adapter is then
plugged into the wall. Cleaning time varies depending on the mA
rating of the adapter.
Electrolysis is ideal for anything metallic, including iron objects.
I've tried this home electrolysis method and sometimes it works
well and sometimes it doesn't. I don't recommend it, tho, because
the adapter tends to heat up quickly, and you can't leave it unattended
for a single minute because of the very real danger of the adapter
starting on fire. Plus, I'm one of those hardware-inept guys who
can slice off a finger using a screwdriver, so electricity and I
don't mix well. Especially when it involves using electrical accessories
in ways that weren't originally intended.
So is there an undisputed best way to clean coins, especially if
you donít want to undertake the numismatic version of watching paint
dry by using the olive oil soak? I thought Iíd ask the folks who
ought to know: The American Numismatic Association, which is this
countryís foremost authority on identifying and conserving coins
and exonumia. It seemed to me that asking the ANA the best way to
clean coins would be like asking paleontologists at Chicagoís Field
Museum the best way to dig up dinosaur bones. According to ANA Museum
curator Robert W. Hoge, there is no best way. There is no "ANA
endorsed method for cleaning undertaken by non-professional conservators,"
Hoge wrote in a reply to my e-mail, "except perhaps to recommend
repeated baths in changes of distilled water, with a final thorough
and quick drying with an oven or hair dryer."
He added, "You might check with museums in your area to see
what they do for conservation needs" and signed off with a
"Good luck." Uh-huh, sure. The closest thing to a coin
conservator in my area is Maury The Fist, and heís a bigger authority
on burying things, not digging them up.
Seeing that Americaís foremost coin conservators donít have an
official prescription to keep us from ruining our coins, Iíll pass
on the method Iíve been using on my more notable coins with astounding
success Ė even for the nightmarish baked-on caked-on corrosion Ė
with no apparent damage to the coin whatsoever. Best of all, it
works in under a half hour. Itís a method I found posted last September
to the Findís Relic Hunting Forum by someone in Florida who posts
by the name of The Mayor.
One of the main ingredients of A&H Super Washing Soda is sodium
carbonate, which is two extra sodium molecules and a missing hydrogen
molecule away from being sodium bicarbonate (better known as baking
soda), except itís too busy spending its time being soap. This method
works through some "Beakmanís World" home game version
of chemical electrolysis brought on by the interaction of the aluminum
foil with the sodium carbonate and other assorted A&H-manufactured
mystery guest chemical ingredients.
First, a word on what this cleaning method will and wonít do. First,
it doesnít work on anything iron. It does work like a charm on anything
brass, copper, silver and old nickel (V nickles supposedly clean
up nicely using this method, but I havenít found any to find out
for myself). Best of all, it causes no pitting unless the coin was
pitted to begin with. Because this cleaning method removes all corrosion,
it will strip off any pleasant, attractive green patina from copper
objects. Patina is, after all, a form of corrosion, so if you want
to retain any of it, use the olive oil soak. This method does not
work well on modern nickels and clads, and it doesnít work at all
on zinc pennies -- which doesnít matter anyhow, since cleaning clads
this way is a waste of time and washing soda because nobody displays
clads. The only fitting thing to do with clads is to roll Ďem through
a coin tumbler for spending.
1) A shallow glass dish, like a casserole dish, or glass jar. For
a few coins or small objects, I use a small Ball, Mason or mayonnaise
2) A piece of aluminum foil large enough to fit in the bottom of
the glass container.
3) One box of Arm and Hammer Super Washing Soda. Not baking soda,
but washing soda. Itís found in the detergent section of most large
grocery stores. Nothing else will work except A&H washing soda.
Fill the glass container with HOT water. I find the best results
always happen when I put the container in the microwave and get
the water boiling. If you just run real hot water out of the faucet,
the cleaning method doesnít work as well.
Take the piece of aluminum and use your finger to smooth flat any
raised wrinkles. If a coin sits on a raised wrinkle during the cleaning
process, it will create a dark spot on the coin. (If this does happen,
the spot can be removed with another cleaning.)
Put the aluminum in the bottom of the container. (Use something
like a pencil to push the foil down if the waterís been microwaved
Drop in the coin to be cleaned. If youíre cleaning more than one
coin, donít let them touch each other. For best results, donít mix
metals. Clean silver with silver, copper with copper and brass with
Dump in two or three heaping tablespoons (depending on how much
gunk is on the object) of the washing soda into the water and stir.
The washing soda doesnít need to be completely dissolved.
The whole works will start foaming and fizzing like grandmaís dentures
in a glass on the nightstand. In a short time you will see the encrustation
start to fall away and the water take on a funky gray-brown color.
Let the whole project sit until the water has cooled to room temperature.
Then pour out the water and retrieve the cleaned coin. In most cases,
one time through this cleaning process will do it, but if the coin
is still crusty, repeat the process as many times as necessary.
You wonít hurt the coin by cleaning it repeatedly this way. Another
thing: If you have to clean the coin more than once, put in a new
sheet of tin foil. The process, youíll find when youíre finished,
causes the foil to begin dissolving around the edges.
Once your coins are cleaned to your satisfaction, place them in
a protective sleeve or collection album. Contact with the oils in
your skin and the air will cause tarnishing.
This method worked great on the slightly gunky wheat pennies I
dug up over the past year and the less than clean coins I have been
picking out of pocket change over the years. But how about the numismatic
equivalent of Momís worst laundry nightmare? I had just the tickets:
three coins I dug up in a suburban Chicago forest preserve last
summer. These were a heavily tarnished 1905-O Barber dime (center),
and a 1976 Roosevelt dime (right) and a 1984 Canadian cent (left)
which had been in the middle of what was once a burn pit. The dime
and penny had been subjected to an excruciatingly hot fire -- hot
enough to melt chunks of glass which had been lying next to the
coins. The Roosevelt had been burned so badly, the metallic coating
had bubbled up and away from its core.
As you can see by the "before" scans above, the penny
and dime were cooked and corroded beyond recognition.
In this "after" scan, you can see what major miracles
can be accomplished with the washing soda cleaning method. A single
cleaning cycle cleaned the Barber quite nicely, and lifted enough
crud from the Canadian and Roosevelt to at least identify them.
A second cycle finished removing all of the corrosion from the Canadian
and enough from the otherwise unsalvageable Roosevelt to make a
few additional cleaning cycles worthwhile had this been a display-worthy
© 1999 Scott Buckner
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