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Ancient Coin Cleaning Instructions

The main objective to cleaning coins is not to reduce them to bare metal lumps. You should remove the dirt and encrustations and leave the base coin alone. A coin with its patina* intact will be worth considerably more than a bare metal coin.

* PATINA  is a thin film of corrosion, usually green, that forms on copper and bronze as a result of oxidation.

The patina of an ancient coin has taken centuries to form and has helped to protect the metal of the coin from the elements and further corrosion. An ancients coins patina can appear as green, brown, black and many shades in between. It is part of a coins history and as such, should be left as intact as possible. The value of a coin that has had the patina removed can be severely reduced.

Ancient silver coins can also have a form of patina on them, but we call that Toning. Toning can range from a very light to a very dark grey. A properly toned silver coin can be very pleasing to look at, as opposed to the bright silver coins that are so common today. So please, if you have a toned silver coin let it be.

Soap and Water

• A simple way to clean coins is plain soap and water. Fill a cup with warm/hot soapy water and swirl it around for a bit then empty out the dirty water.

• Rinse the coins to get rid of the soap residue

• Dry the coins thoughroughly

Distilled Water Soak

• This is probably the simplest way to clean coins. Just let the coins sit in distilled water anywhere from 3 hours to 3 days. soak in distilled water. A water soak can run from a few hours to a few days to a few days depending on the results you see.  Basically as soon as they are not getting any cleaner it is time to move on to another technique.

• Check the coins periodically and give them a light brush weith an old tooth brush.

Olive Oil

• Put the coins in a glass and fill the glass with olive oil until the coins are covered. Leave them in the olive oil for 3-4 days. The olive oil will penetrate the dirt and soften it.

• After the 3-4 days, take the coins out and pat them dry with a paper towel. Mix a batch of TSP (Tri-Sodium Phosphate...a cleaner available in most home repair or paint shops) with one teaspoon in warm water. Put the coins in the TSP solution for 5-10 minutes. This will remove the olive oil and some of the dirt.

• Rinse the coins in clean water to remove the TSP residue.

• Take an old toothbrush or stiff bristle brush (plastic, fiberglass, etc.)and gently brush away at the coins.

• Examine the coins. At this point, some of them will be clean and identifiable. The ones that are not should go back into the olive oil for another 3-4 days soaking.

• Some coins will have dirt in recesses, between the letters of the inscription for example. See the Finishing Touch section for tips on this.

• Repeat this process until you are satisfied with the result. I have left some coins soaking for weeks before I was satisfied with the result.

Cleaning Techniques (silver):

• This is a fairly simple and fast technique. Allow the coin to sit in lemon juice (a few minutes if the juice is concentrated or a few hours if it is diluted). Then rinse the coin with running water for a few minutes.

Finishing Touches

Small Area Touch Up

Small areas (for example between the letters of an inscription) can be cleaned with a steady hand, bright light and a variety of tools. Which tools you will use will depend upon your personal preferences and what you feel comfortable using.

• dental tools

• sharpened bamboo sticks

• toothpicks

• *a glue gun

*A special note should be made about the last one. Take a glue gun (the type that uses glue sticks and can be found in any arts and crafts store) and put a glob of glue on a coin. Let the glue harden and then remove it. The glue should be relatively easy to remove. If it works right, the glue will lift the dirt from the hard to reach areas. With a few reservations I can tell you that it works. When you pry the hardened glue off it pulls the dirt out of even the tiniest spot. It may not get all of it off with the first attempt so multiple applications may be needed. Make sure the glue has hardened before trying to remove it. The reservations are:

If you are working on a 'silvered' coin the glue may take the dirt and the silvering off at the same time. So don't use it on that silvered antoninianus. If the coin has subsurface pitting, then the glue may expose the pits.

So, if you are careful about which coin you use it on, then this technique will work.

Identification:

This is the book that all the best ancient coin enthusiats use. It contains pictures of just about every ancient coin, tells you the name, and gives a brief description.

HIGHLY RECOMMENDED!