The Complete Guide to Uncleaned Ancient Coins

By Evan Rankin

One of the most common ways of becoming tangled up in the ancient coin hobby is to buy one or two ‘uncleaned’ coins on eBay or elsewhere. From here you develop a sense of the coins and eventually how to clean them with skill and efficiency. In this article I’ll address many of the questions a beginner may have, as well as many tips and hints. First I’ll address the issue of dealers selling uncleaned ancient coins.

The first question that comes to mind for many people is ‘Are these real?’ Generally, the answer is yes, they are genuine ancient coins, dug out of the mud somewhere in Europe (sometimes elsewhere). While, this first question is met with an honest answer, there are dealers who do not have the most integrity. Some claim that there has been "Gold Found!!” in there lots. This is simply not true. Unless the dealer has spiced up the lot with some miniscule gold coins that equal almost no value, you will never clean up a coin that is gold. Keep in mind that you, the consumer, are the last to get the coins in a chain of probably five people- the farmer who digs the up, the local profiteer who buys them, the middle man, who buys them from the profiteer, the dealer, who buys the lot from the middle man, and finally you. In that sequence, the coins are cherry picked and sorted to filter quality, and pick out some obvious rarities, many times. So, to sum up: you will not find gold!!

‘What’s this Patina thing?’ The patina of a coin is a layer of oxidization that has occurred over hundreds of years to protect the metal. The patina comes in all sorts of colors- green, black, golden brown, and many more, but always remember that it is not dirt. Many collectors won’t buy a coin that has been stripped of its patina, so you’re collection may be worthless if you have stripped them all.

‘How do I go about cleaning these lumps of mud and metal that arrived in my mailbox today?’ When you first get your batch, you should try to separate which coins need lots of cleaning and which don’t. Wash all the coins with water and a toothbrush, and some dish detergent if you like. This should help you determine which coins are going to need the most work. There are many, many methods of cleaning, but it all depends on the metal type. As a rule, bronze should be cleaned mechanically (ie. with brushes, and toothpicks), and silver should be cleaned chemically (ie. with ammonia).

Following is a list of cleaning methods:

General Cleaning- Your best friends in cleaning coins will be toothpicks, toothbrushes, soap, water, and patience. For cleaning in between letters, toothpicks work great, as do bamboo skewers. For the more seasoned cleaner, metal dental picks can be used also, but these run the risk of scratching a smooth patina. Plastic pointy objects (disposable utensils) also work, these take more time, but the patina is not scratched nearly as easily. Often, brass-brushes are needed. These should only be used to get rid of crud that is completely caked on, as the brush can destroy the patina as well.

Bronze/Copper

Olive Oil - This one is simple enough. Place the coins in a container of olive oil (preferably not virgin) and allow them to soak for a while. How long depends on how dirty the coins are. This can take anywhere from a few weeks, to a few years. Over time, the oil penetrates the crud, and breaks it off of the coin. Any type of penetrating oil will work (i.e.. WD-40). Have patience, the result is often worth the wait.

Distilled Water - This method is somewhat quicker than the olive oil, but it take more effort. Place coins in distilled water (available at any grocery store) and allow them to soak for a day. The next day, change the old water out with fresh, distilled water. Repeat this for as long as you feel it is necessary. The distilled water ions attach themselves to the crud and break it off gradually. Many people have great success with this method.

Gringgotts Coin Cleaner - Invented by a friend of mine, this product has proven itself a valuable tool in cleaning coins. Follow the instructions on the label, and you can practically dissolve tough mud, or at least loosen it substantially. Completely safe for patinas. Available at ancientcoinvault.com

Ultrasonic Cleaner - Some people have success with these, while others do not. It all  depends on the model you get. The made-for-home-use types don’t  do almost anything, while the industrial types will clean your coins by shaking the crud off of them.

Electrolysis - The plans for this are on the web. This method should only be used, if everything else has failed totally. It will strip the patina off the coins in no time, although occasionally it reveals a nice coin. This cleaning method only takes a few hours, but is generally frowned upon. A quick note about this- always use sodium bi-carbonate, never salt. This may take slightly longer, but it will be easier on the coin.

Glue Gun - This should be used only if the coin doesn’t have a flaky patina, or silvering. Simply apply the glue to a spot on the coin and allow it to cool. Peel the glue away. Some dirt may come off (this is good), or the glue may tear a sections of patina away (this is bad). Be warned: this is a quick way to really ruin a coin, and, like electrolysis, should only be used as a last resort.

Lye - Once again, a last resort method. You can buy lye under the name Red Devil drain cleaner. Be VERY CAREFUL- lye can blind you. Always wear gloves when handling lye. Follow the Instructions on the label, and put the coins in the solution. Cleaning can take a few weeks, but the results are often worth you’re patience. Lye will more times than not, kill any patina, and replace it with a brown/golden layer.  Watch your coins very carefully for signs of pitting caused by the solution.

Rock Tumblers - Generally a no-no. Rock tumbler may help to knock off some dirt, but it will also destroy patina, any details, and a possible attribution, just as quickly.

Silvered Coins

Soap and Water - This is generally the only way to clean silvered and silver-plated coins, without damaging the silver.

Silver

Ammonium - Windex works fine. This will clean the coin without damaging the silver.

Lemon Juice - This works great on hard to clean silver coins. Simply leave the coin in the juice until the desired amount of crud has been removed. It’s recommended that you the give the coin a quick scrub every now and then, and rinse it off with fresh water.

Lye -Works as is stated above. Lye can clean silver coins better than almost anything except hand cleaning. It will leave luster, and toning intact. Once again, BE CAREFUL!

Preservation

Renaissance Wax - Follow the instructions on the label. Ren-Wax can preserve a coin indefinitely and protect it from Bronze Disease. Many of my friends have found it extremely effective.

2x2 Flips - Great for storing coins with their attribution information. You can get these at FORVM. Just make sure that they are PVC free, as PVC will cause Bronze Disease and any number of other bad things to happen.

A note about Safes - If you have a valuable collection you may consider buying a safe.  Research this topic carefully! Many safes keep documents safe during a fire by sealing in moisture. Moisture can cause bronze disease, and often other things that could destroy you’re  coin.

Bonze Disease

This is caused by chlorine reacting with moisture in the air to form Hydrochloric acid. BD usually appears as a green powder on the surface of coins. Over time, BD will destroy the coin, and needs to be treated aggressively. Treatment is as follows:

Brush away the green powder and then boil them in distilled water with sodium carbonate (washing soda, but Gringgotts works well too). Allow them to soak and cool overnight. Repeat this process three times. Dry them out using either rubbing alcohol or low heat, or both, and seal with wax if you can.  

Attributing

This can be a long and painful process to the beginner, so I’ll give some hints and tips to help you on your quest for an ID. First, remember that the bulk of your uncleaned coins will be late Roman, that is to say, Constantine I and later. Second, use Wildwinds.com. It is, by far, the most comprehensive database for ancient coins of all types. Wildwinds lists its coins by RIC (Roman Imperial Coinage #) and by Sear. One of the most useful tools, however, is right here at ForumAncientCoins.com. Use its partial inscription search to find a list of emperors that could belong to your coin. Also here at the Forum, Van Meter, which is a reference book for Roman imperial coins, is available for $35 with the purchase of a coin.

Good Luck and remember: every coin is different. Be adaptable, and you will find a great deal of satisfaction in this hobby.

Special thanks to Forum Ancient Coins, which has been invaluable to my education of this hobby. Thank you to my parents who’ve put up with this, and the good people of the board, who’ve helped me every step of the way.