Cleaning & Conserving Coins

Cleaning Coins: Introduction

Welcome to the fascinating adventure of uncleaned ancient coins! We hope you will find this hobby as addictive and educational as thousands of others. With the Articles on our Website in your hands everything needed to turn an ancient piece of metal into a unique artifact of historical value worthy of being treasured for generations to come.

These handmade coins have been recently recovered from the ground by metal detectorists throughout Europe, Asia Minor and North Africa and are in the same condition as when retrieved. You will be the first to have the opportunity to see what’s beneath the dirt of the ages. With the help of our Website you will also be able to identify under whose reign the coin was minted and, in many cases, be able to tell a variety of other interesting information regarding the coin.

Most of the coins you have will date from the 4th century A.D. and be of Roman provenance. This was a period of extraordinary change in the Western world. Christianity was quickly reaching the farthest corners of Europe and replacing old pagan rituals as the dominating religion. The Roman economy faltered under the strain of continued invasions by Barbarians. To remedy this situation, the various emperors of this time period resorted to issuing large amounts of bronze coinage. The coins were paid to citizens of all walks of Roman life from the nobility down to the lowest paid peasants. Gold and silver coinage was produced as well but these played a more important role in the army and within the government. This left the copper coins for the average man who may have bought with it the family’s bread, oil, clothes and so on. Just as now, the copper coins carried little value individually and thus many were needed to make purchases.

For this reason they were easily lost and attempts to recover them were not strenuous.
Over time, the coins became embedded in the dirt and were lost forever. Forever, that is, until modern times. Mainly through the efforts of numberless aficionados with metal detectors these coins are now being unearthed. The detectorists are for the most part seeking other antiquities and either discard the coins or pile them up until they have enough that someone will buy them in bulk. These in turn eventually find their way into coin dealers who sell what they do not want for themselves. Because it often takes a long time to clean them it is not cost efficient for them to undertake this task even when a few of the coins turn out to be valuable rarities.

The chance that some of the coins can be worth hundreds, or even thousands of dollars adds a “treasure hunting” aspect to the hobby that draws many new people each year. Even while most turn out to be rather common examples that when cleaned fetch little more than the initial price paid the expectation that builds on the “what if” factor is enough to make many people continue to buy more much the same way as lotto tickets. However, unlike the lotto, the coins you clean which turn out to be of little monetary value are almost always of great historical and educational value nonetheless. You may well find it hard to get rid of the same coin that took you many hours to clean.
To many collectors cleaning is half the fun (or more!). There are many ways to clean these coins. In time you will find a preferred method of your own as most try slightly different variations and some zealously guard their secret coin cleaning recipes. Unfortunately, it takes a rather long time and a lot of effort to do a great cleaning job. After being under the ground for over 1,500 years these coins do not like to shed the dirt of the ages so easily. Rushing the process by taking shortcuts is only bound to disappoint you with inferior results and/or damaged coins.

The traditional way of cleaning ancient coins has been to soak them in olive oil for a long time. Sometimes weeks or even months. Every so often the coins are taken out and they’re vigorously scrubbed with a toothbrush and dish detergent. In time, the dirt layers soften and become muddy and melt away under the scrubbing. Little by little the coin is revealed until entirely clean.

In more recent times additional methods have proven equally successful and, thankfully, have involved less time to achieve the same results. For one, olive oil has no magical advantages over other types of oil. The main difference seems to be the viscosity of the oil. A lighter weight oil will penetrate dirt faster but not do as good a job at softening it. A heavy oil given enough time turns the hardiest crust to mud but the length required will try the most patient of collectors.

And oil is only one of the ways to clean dirty coins. Many now substitute oil with water to accomplish the same thing. Some coins are found in a state clean enough that they don’t really need a soak of any kind. These often have little unsightly hardened deposits on the coin’s surface that can be picked at carefully using a dental pick or an Xacto-type scalpel. Magnification and great care must be taken to avoid scratching the coin since this happens much too easily, often ruining the coin. Some coins have even, light dirt coats which can be removed by adding a layer of Elmer’s glue and then peeling it off and repeating the process. While this method works quickly it is labor intensive, tedious and not for every coin. Specifically not recommended are those coins which have shiny patinas. The glue will remove some of the patina and turn the shiny surface matte and sometimes pitted.

A coin’s patina is considered visually attractive and to be protected as much as possible. The patina is simply a thin layer of oxides that has formed on the surface. It takes various hues of green and sometimes a shiny black or red. If you receive a coin which has a patina do not try to remove it during cleaning. Removing it often exposes a pitted, awful looking core of a coin. The patina, in fact, has become a protective cast to the coin and prevented it from deteriorating further.

Unfortunately, it is often the case that in the soil the coin has little chance to form an attractive patina. Very frequently uncleaned coins will have stubborn dirt that does not seem to be affected much by the cleaning and soaking cycles or the other methods already discussed. For these coins there is an alternative which many use indiscriminately if only because it is very effective at removing dirt in a short period of time. This is the process of electrolysis.

There are several methods which are decidedly not recommended. The use of acids, polishing agents and wire brushes will almost always damage your coin quickly. For bronze coins acids are especially harmful and will make the surface of the coin pitted long before the acid eats away at the dirt. Most polishing compounds use abrasives that will gouge the metal and when they don’t they use chemicals which invariably always are too strong for the ancient copper alloys used in the coins. And the use of wire brushes, steel wool or similar will make short work of both ancient dirt and ancient coins alike.

In the end it bears repeating that the more time you allow the cleaning of any one coin the more likely you will be rewarded with a coin worthy of being displayed.

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