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Coin cleaning success

Scott Abel from contacted me a couple of weeks ago about his coin cleaning solution and techniques. I suggested he try it on the Ancient British Stater, which I valued last week. This was particularly badly encrusted on one side. The transformation has been remarkable and as a result I have revised my valuation from £120 to £200. Here is my updated identification and valuation report.

Scott from Gladius Coins has written the following article on the cleaning process and advice on coin cleaning.

Cleaning the Ancient British Stater

Evaluation: contact with fire

Upon receiving the coin for evaluation it was apparent that the coin had at one point or more over the last 2,000 years been in contact with heat. This was possibly from a fire but also potentially from chemicals.

This can be a common occurrence in certain areas of the UK depending on soil quality. Farmers in years gone by would burn the stubble left after harvest to lower the acidity of the soil, kill pests or to reduce nitrogen tie-up. This has happened for millennia up until the 1990’s. Since then farmers have massively increased the use of chemicals in their fields some of which can have similar effects on silver.

Soak in Gladius cleaning solution

I’m confident this coin has seen many stubble fires. This became more evident when the coin was placed in Gladius coin cleaning solution. The solution works by rapidly softening the surface of hard encrustations with no effect to the general patina of a coin. This coin was placed on the solution for five days initially. In comparison to distilled water or other harsher cleaning products this is a relatively short time to bathe such an encrustation.

Research on the coin

During the bathe, I researched the coin as its important to know what you are cleaning and what you can expect under an encrustation or just general dirt. With some coins this isn’t always possible. However, I recommend doing research as soon as possible and before detailed cleaning of a coin. This will ensure you know the lay of the land.

Detailed cleaning

Five days later, with the coin under my 10x Stereo Microscope, I could see some of the encrustation was starting to lift on its own. This is always what you want to see as it helps avoid either a longer bathe or damaging a coin’s patina by forcing the encrustation off.

On that first session with the coin, I removed two thirds of the encrustation using a wooden BBQ skewer, a composite cleaning pencil supplied by Graham Dempsey, some very delicate work with a brass needle. I used some drops of gladius solution to help soften below the hard surface encrustation, whilst going through the process.

That first session took no longer than 30 minutes to complete. With a third of the coin still covered with the hardest of the encrustation, I used a brass needle to very delicately scratch the encrustation surface. I then put the coin back into the solution for a 24 hour soak.

Second soak

The scratches in the encrustation did what was required and helped the solution work its way into the encrustation. After the second soak, this lifted easily, leaving 90 – 95% of the coin encrustation free. At that point I really couldn’t do anymore to the coin; the patina was perfect and the coin looked considerably better both in hand and under the microscope. Unfortunately, a very small amount of pitting was evident in some small nooks and crannies of the coin. This made it impossible to clean without the potential for surface damage.

Final result

Here is the coin, before and after cleaning

Advice on cleaning coins

Coin cleaning can be seen by some traditionalists as a bad thing. However I’ve personally never seen an identifiable ancient coin in anyone’s collection that hasn’t had preservation of some kind. Nor have I seen an ancient coin, in one of the many auctions I’ve participated in all around the globe over the years, that hasn’t again been through a preservation process.

Cleaning medieval hammered coins

This however doesn’t mean that every coin should be cleaned or preserved. A medieval hammered coins for instance are generally quite soft and therefore susceptible to considerable damage if cleaned incorrectly. I would strongly recommend contacting either ourselves at Gladius Coins & Antiquities Ltd or another coin expert before beginning the prosses of cleaning and preservation. We are happy to give free advice to anyone in this position. Other coin types that would require expert help would be milled coins for exactly the same reason as hammered coins and any coin made from precious metals such as Gold or Silver.

Practice on cheap coin

If you want to start cleaning coins I would highly recommend practicing on some very cheap bronze Roman coins. These are readily available on many sites including our own A 10 x zoom stereo microscope is a must, you can pick these up for as little as £30 from various places. You’ll also need composite cleaning pencils which again are available on our site or from Graham Dempsey at and some wooden BBQ skewers. Once you are confident and practiced you can on occasion use a scalpel, bronze scalpel or a bronze needle for detailed work. However, do not use these on coins you want to keep or sell until you are 100% confident.

Gladius Coin and Artefact Cleaning Solution

My skills in coin cleaning come from years spent cleaning bronze roman horde coins and artefacts. However, I have become a bit more specialised in burnt and horn silver this past couple of years.

This was borne out of the development of gladius coin and artefact cleaning solution. My business partner, Misko Miletic, first developed the solution with the key goals of being 100% environmentally friendly, 100% safe for all metal types and also 100% safe to use for people. We are very pleased to have achieved all three of these goals. The product’s ingredients being all UK food grade certified.

Our cleaning solution, together with a Composite Cleaning Pencil can be purchased at

Contact Gladius

Here at gladius we offer coin and artefact evaluation, cleaning and preservation services along with general coin and artefact sales and live online auctions.

We give advice freely and are always happy to make new acquaintances and collaborations.

You can check out our website at or feel free to email us at

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