How have
ancient coins been preserved so you can collect them? 
Uncleaned Roman Coins
|
In antiquity there were few banks and no savings accounts. Those
who could save invested money in property, deposited it at a temple, or buried it as
soldiers often did before a battle. Of course, people sometimes lost coins.
Ancient coins are usually found buried,
and most unearthed coins look like these: covered with dirt and corrosion
products so that few can be identified. Turning these dirty lumps into collectible coins
is a job for conservators, who use various careful processes to remove dirt and corrosion
products without damaging the actual surface of the coin.
The dirt cannot just be washed away, so the first task is
to loosen and remove it so that the conservator can assess whether further cleaning is
indicated. Most unearthed bronze coins are in fairly rough condition,
not
worth further processing. These find their way into dealer "junk boxes." |
| Collectible bronze coins
normally develop a desirable patina, which the conservator will not disturb. Silver coins
often develop a dark patina which will be treated to reveal a clean silver surface.
Professionals can accomplish this without loss of detail. |
Ancient coins often
suffer from encrustation or deposits, which are firmly attached to the
coin and cannot easily be removed. This is common in legends and detail such as hair
curls. Removing or minimizing encrustation involves highly skilled, delicate hand work
under a stereo microscope. |
| Once the coin has been
cleaned, its surface may be chemically reactive, and chemically stabilizing the surface is
very important. After this, the conservator may add a protective coating to prevent changes. Classical Coins uses a coating developed at the British
Museum. Properly stabilized coins will not deteriorate after cleaning, although they may
tone or darken somewhat over many years. |
Bronze ancient
coins - any ancient bronze object - can suffer from a corrosion process known as
"bronze disease," which every collector should beware of. Its symptom is spots
of powdery greenish-blue deposits on the coin. If left untreated this condition can
destroy the coin. If you suspect a coin has developed bronze disease, consult a
professional. To prevent it from developing, keep your coins in a low humidity
environment. |
