(Cleaning Ancient Coins)

Cleaning ancient coins is a complicated question that has many different answers. If I were a "purist" I would have to tell you that you never clean ancient coins, that nature has created a "patina" that protects the metal from deteriorating further, and that by removing it you only cause harm to the coin. It is more desirable to have an ancient coin with the patina intact. The value of the coin diminishes when it is down to the "bare" metal. The information contained here is limited to my personal experience and knowledge. It is highly recommended that you visit the other links provided. This is a brief overview of cleaning ancient coins:

First you have to find out what you've got yourself into. You'll need to rinse and brush your coins with dish or hand soap. Rinse well. If you've got details showing already, your really lucky. Unless it comes completely clean during this first process, you might as well figure your coins are going to need to soak. I usually start with two weeks in distilled water to start and then clean with toothbrush and soap again and repeat. You can speed up the process by using a cleaner like Oxyclean, which helps remove the loose dirt or another product called Tri-Sodium Phosphate or TSP. It is primarily used as a pool and driveway cleaner. Dilute as necessary as either of these can disrupt the patina if you use too strong a formula. Oxyclean loses it's potency early while TSP can stay active for hours. Always monitor and error on the side of moderation. Normally both these chemicals help remove the loose dirt. Another alternative is to use a dry brush and try and remove as much dirt as possible. Course this makes a dust ball that can be seen (and inhaled) for miles away, but it also gives you a quick peek into what you may or may not have and what course of action you will need to take. For the most part, get ready to spend your money on distilled water and containers. The longer they soak, the easier they are to clean. Water should be changed when it becomes cloudy or if you see dirt resting on the bottom. Brush with soap and water. Repeat. It is not uncommon to see a white film develop on some soaking coins. This is usually a sign that all the soap wasn't removed. Pull coin(s) and rebrush without soap and rinse well. Patience is a virtue. I have coins that have been soaking for almost two years now and their still not ready. Course this means that I've already determined that the coin has some potential or uniqueness, and I want to see it come out okay.

2) An alternative to distilled water is the old fashion way, and by that I mean soaking them in olive oil (or WD40) for several weeks to months. (Note: Oil will darken these coins) Many of the people who sell unclean coins, state in their instructions, that coins will be clean in about four days to a week. This will rarely happen! Most coins will have to soak and be scrubbed for weeks and sometime longer. Patience is truly the best virtue when cleaning ancients. While they’re soaking, I would take them out every other weekend and scrub them with a stiff toothbrush (Denture is best - cut down bristles) and liquid soap (rinse well) and return those that still do not show enough detail to attribute. This technique is fast becoming obsolete in the face of distilled water. Still there is about a 5% acidity level in olive oil and yet long term storage doesn't seem to hurt the coins. Better than olive oil is lanolin. You have to be careful and make sure you get the kind that has a chemical separating agent, which keeps it liquid. There is pure lanolin oil that is not effective as it is too thick and doesn't penetrate the coins.

3) Desperation will set in on some coin, as no matter how long they soak, they will continue to be covered with a "cement-like" substance that is harder than diamonds. :) This is where most of the coins get damaged. Many people try a more modern approach by using caustic chemicals, metal cleaners, and even sharp objects. I have many disaster stories of how I ruined a coin by trying to clean it with these methods. Remember to be patient. Many times I thought the coin was as clean as it would get, but left it soaking and was surprised when I could finally see some detail. This doesn’t always work, as there are numerous coins that, because of time and nature, are merely worn slugs, but if there’s dirt, there’s still hope.

4) The second part of my tutorial, "Advanced Cleaning" continues the process. Below are some links which deal with the "professional" cleaning of coins from a numismatic point of view, and explain the more technical methods of cleaning which is usually beyond my capabilities. I know there is other web pages out there, just try a search engine with "cleaning ancients" and some more should show.



Hope this helps! If you do come upon a magic formula for removing 2,000 years of dirt safely and quickly from ancients, please don’t hesitate to let me know. My wife would greatly appreciate it, as she is tired of smelling olive oil!


William Peters