A Guide to Artificially Toning Coins

First, let me begin by saying that I am not advocating doctoring coins. Some people do it for their own enjoyment and some people have intentions not so pure. I am simply passing along information that I have learned through research and trial and error. What you do with this information is entirely up to you.

Second, I will not use the words "natural toning" or "artificial toning" in their usual context in the collector's universe. Any such occurrence of these words appearing together is not intentional. There is much debate as to what is defined as "natural toning". A coin stored in an envelope for 40 years with exposure to sulfur is usually natural toning. A coin chemically treated for 20 seconds is usually considered artificial toning. But, what about a coin stored in an environment with the intentional presence of sulfur for 2-3 months? Chemical reactions are a naturally occurring process, but human facilitation of the processes clouds that line. Numismatic professionals disagree on the very definition of AT or NT, and identification of same is even more so subjective.

Finally, dangerous chemicals are involved here. I won't tell you specifically where to obtain them-you can find out for yourself in 15 seconds with an Internet search-I did. I strongly encourage you to understand the chemical properties and use proper precautions, including obtaining the MSDS and having adequate ventilation and protective gear. Again, this is simply for informational purposes. What you do with the information is up to you.

My Learning Process

Coin collecting has grown enormously in popularity, largely in part due to the frenzy of new collectors the US Mint's State Quarter campaign created. This extra demand has crept into all niches of the coin market-including the much sought after market for toned silver coins. Many creative coin doctors have developed more sophisticated techniques to generate the supply to match this increased demand. However, it all boils down to chemistry-how the chemical compounds in the silver coin reacts to chemicals in its environment.

I have been intrigued over the past years with toning coins and was determined to figure out how some of these talented coin doctors create such wonderful works of art. Internet searches for "Toning Coins" revealed frustratingly little information other than message boards debating the topic and home-grown techniques using such items as potatoes and dandruff shampoo that just didn't work for me.

So, I hit the chemistry books for a little background information. Toning is nothing more than oxidation (just like steel rusting) of silver. The silver chemically reacts with its environment-whether that is air, coin container, or a chemical bath-to change from the natural silver through a spectrum of colors and eventually turns black. It is the presence of sulfur that facilitates this color transformation.

My first experiments were with pure sulfur in a powdered form. It is roughly the consistency of flour and has a variety of uses including lawn care and, yes, explosives. This chemical is readily available on the internet-just do a quick internet search. Recall, that the chemical reaction takes the silver through a spectrum of colors, ending up with a dull black color. I quickly learned that direct exposure of the silver to the pure powder resulted in a quick transformation directly to black, which isn't at all what I wanted. Also, it was difficult to get an even coverage on the coin with the powder.

From there, I wanted to dissolve the sulfur powder into a liquid form to lower the potency and increase the consistency with which it would come into contact with the coin. Alas, I quickly learned that sulfur doesn't dissolve in water, or any other substance that isn't too harmful for my purposes. I ended up concocting a suspension-mixing the powder with a thicker liquid that would, after vigorous mixing, would allow the particles to be suspended and react with the coin in a more desirable fashion. Ordinary shampoo was the agent of choice. The results were acceptable, but not perfect. Complete immersion of the coin with periodic stirring would often produce the brilliant spectrum of colors I was looking for. However, the suspension wasn't a perfect distribution method and the results were not consistent. In addition, digging coins out of a tub of sulfur-smelling shampoo goo was messy.

When rinsing the coins off in hot water, I then realized that heat was another variable in the equation that aided the toning of the silver coins.

Further research led me to discover Potassium Polysulfide, also known as liver of sulfur or sulfurated potash and develop the techniques detailed herein. Just perform an internet search and you'll find chemical companies or silver crafting suppliers who will be willing to sell you a quantity.

The Potassium Polysulfide Method

After much research and experimentation (not to mention countless ruined silver coins!) I have developed the following method of toning coins.

Gather the following supplies/equipment:

Heat source (burner, stove, etc)

Distilled water

Ice

Potassium Polysulfide (lump form, rather than crushed)

Household Ammonia

Table salt

Eyedropper

Small fishnet-for household aquarium use

Rubber-tipped forceps

A small pot or pan that can be used on your heat source

Towel

Silver coins. I recommend inexpensive coins you're not afraid to ruin until you get the hang of this.

Soapy water or alcohol (not the drinking kind!)

First, create the toning solution. This is more of a guideline rather than an exact recipe. The stronger the solution, the faster and more dramatic the reaction will be. I find it best to use a weaker solution so I have better control over the reaction. I mix 1 quart of distilled water with a small piece (maybe the size of 2 peppercorns) of the potassium polysulfide, which should start dissolving immediately. The solution should be a pale yellow, clear liquid. Add approximately 1 tsp of table salt and 1 tbsp of ammonia. These will make the colors more vibrant. Different types of salt (kosher, etc) and different concentrations will yield different results. Experiment! Place this on the burner on low heat. You want it hot, but not boiling.

Second, have a small bowl of ice water handy. Remember, heat speeds up the reaction. Alternative applications of heat and cold will start and stop the reaction so you have better control over the progression.

Third, organize your work area so you have the needed tools readily available. I like to have the ice water near the burner, with a towel under the bowl of ice water. The utensils should be laid out nearby easily within reach.

Fourth, start by placing one coin into the fish net and dip into the hot potassium polysulfide solution. Watch carefully, because the reaction will begin immediately. Remove from the heat and place into the ice water to stop the reaction. Repeatedly dip the coin in the solution and ice water until you reach the desired appearance. The color spectrum generally goes from gold to pink to purple to green, to blue to black with varying shades between.

Fifth, gently use alcohol or soapy water to remove remaining traces of the solution and ensure the reaction ceases

Finally, store in an airtight environment to ensure the coin doesn't naturally react and start the toning process again.

Variations

Varying colors

The previous method above will likely result in a uniform shade over the entire surface of the coin. To get colors to vary, you need to "pre-treat" parts of the coin you want to achieve a color further along the color spectrum.

For spotty or random coloration, use an eyedropper to put a few drops of the solution onto the parts of the coin you want to have colors further along the color spectrum. When you achieve a nice golden color, stop the reaction as outlined above. Then, dip the entire coin in the solution. You will see that the pre-treated parts of the coin will be shades of ping/purple/blue, while the rest of the coin will be gold/pink/purple-all depending on how long the reaction was allowed to progress. Again, experiment!

You can also "paint" the solution using a cotton swab or paintbrush. I'm not overly fond of this because the solution is thin and tends not to stay where you are trying to apply it.

Rainbows

Many collectors love the rainbow of colors achieved when coins overlap and only exposed surfaces tone, resulting in the "arc" across the face. Another example is when only the rims are in contact with sulfur and uniform rings of color spiral inward. This is just a variation of varying colors.

Arcs-simply place two coins in the net when dipping, ensuring they are overlapping to the degree you desire. If you decrease the amount of overlap for subsequent dips, you can create a rainbow of different colors. This takes a little practice.

Rings-This is a little tricky to describe, but easy to execute. Stack however many coins you want to tone this way and place inside the net. You want a neat stack-just as if they're in a roll. Dip the entire stack into the solution and swing the coins in gentle circles. What you're trying to accomplish is shifting the coins slightly in a concentric manner, so a uniform amount of the edge of the coin is exposed to the solution. The more shifting, the wider the band will be around the edge. With a little practice, you'll be able to create concentric rings of toning around the edges. You can leave only the rings, or dip the entire coin again, which will darken the rings and add some color to the rest of the coin.

Alternative applications

Recall that unintentional toning occurs when the coin comes into contact with sulfur in its environment: coin holders, paper, bags, and air. This type of toning occurs over a longer period of time and is often more attractive than our cooking method that takes just a few minutes. Some of these environments also create unique patterns that are very desirable.

Texture-some of the most beautiful toned coins result from the coin being in contact with some textured object with sulfur content (mint bag, paper, etc). The resulting patterns are often breathtaking. To create these textures, simply soak whatever material you are using in the hot sulfur solution and press against the coin. The toning should occur quickly.

Slower Reactions

Knowing that the concentration of sulfur and heat speed up the reactions, you can apply a lower concentration and varying temperature to create coins that tone over a longer period of time. These slower-toning coins often have a very different appearance. Here, I recommend soaking paper or canvas in a diluted solution and allow to dry. Wrap the coins and tuck them away somewhere, checking periodically. The amount of time depends on how weak the solution is. You can create beautiful coins by storing them inside your car in the summer. The increase and decrease in temperature helps the reaction along. Some of the best coins can be created this way, but is the trickiest method because of the varying heat and concentration of the solution.