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Introduction to Coin Cleaning (advanced)
see also:
Coin Cleaning

Cleaning bronze and Romana
Cleaning Copper
Advanced Cleaning

The cleaning and preservation of Ancient Metal Artifacts from Europe, and other parts of the world, is a very worthwhile undertaking, because the relative availibility of these artifacts has never been greater, and because no matter how available ancient metal collectibles are now, they have been, are, and always will be rare. The reasons behind this present and relative availibility are two-fold. Development or Renewal of historically rich areas has created increased archaeological activities all over the world, and the use of easily obtainable, and technologically simple Metal Detectors by the general public is a positive boon to the collector, or future collectors of ancient art.

It is truly incredible just how much numismatic metallica was produced by ancient people, especially the Roman civilization, which lasted in theneighborhood of 800 years. No matter how this present plethora of ancient material is viewed though, one aspect should remain clear in every collectors mind, and that aspect has to do with the truly finite nature of these ancient artifacts. They are out of production, and have been out of production for nearly two thousand years. These times we live in, right now, are very special, because certain factors have come together, aligned,so that you, the buyer, can acquire and preserve some of this wonderfully educational information for yourself.

Of the myriad Bracelets, Rings, Coins, and other metallic ephemera produced during ancient times, (The coins, especially, number in the many millions) these myriad durables of metal cannot come close to stacking up against things like the population of our world today, which is gargantuan when compared to the number of artifacts on the market, or destruction of the various numismatia which has transpired in the last two millenia.   The factorys for these products closed permanently, around the year 1200 A.D. or so, and will never re-open for business. It will pay if you remember this as you build your collection, and your view of history will become greatly enhanced too.

Even though many, many artifacts were produced during ancient times, all that have survived to this day have undergone the nearly spectacular Wear-and-Tear of Time, Lots Of Time, a force that is incredibly powerful in itself, and really must be witnessed to be believed. By acquiring items of great antiquity you will learn to recognize some of that power, and it is the purpose of this report to educate you about that, and to teach you how to easily and safely halt, and even reverse some of the erosive corrosion that takes place on the surface of ancient metals.


It is estimated by some that as much as 70% of the ancient finds of the last two decades have been destroyed, or permanently damaged, by incorrect cleaning. Not only does that waste investment of time and money, all the way around, but in the long perception it is almost a crime against history. It is like depriving the future of valuable information. Some of this misinformation was perpertrated to keep "Inventories" of available coins down. This does not have to be, and by reading this you will be taking a big step towards safe, conscientious, and comprehensive restoration of ancient metal artifacts.



Mechanical Cleaning


The cleaning of metal artifacts should be attempted with extreme care and caution. There are many techniques that are actually hazardous, and there is a very good chance of harming an artifact during its cleaning, rather than enhancing it. It is fair to say that if an artifact posesses good detail, and a uniform patina (Layer of oxidized metal) it is best to leave it as it is. Many times the patina of metal is an actual and entire Layer of the metal itself, so that its removal also includes removal of information vital to the items identification, and value. If you are worried about cleaning a piece of metal, the rule of thumb is Don't. All types of metal cleaning are erosive, to some extent. Control and Minimization of this erosive process is what makes the difference between crude and simple Cleaning, and Restoration/Preservation.

One commonality among novice collectors seems to be the attempt to clean metal by "Shining" it with chemical preparations. Many acids have been tried with only varying degrees of success, and they are usually quite dangerous, and are very hard to control. Many times a secondary chemical needs to be used to halt or nullify a chemical process begun with acids. Most chemicals used to clean coins are very carcinogenic. There is a silver dip that is used by professional conservators, people who meticulously preserve old plated serving sets and the like, and this dip is called acidified thioreau. It chemically dissolves silver sulfide. It is highly carcinogenic although it is sometimes sold in grocery stores as silver cleaner. The amount of rinsing needed to halt the reaction created by this treatment prohibits its use on many things, and its a pretty sure thing that the average person attempting preservation will hurt themselves, and the things they are trying to clean, with chemicals like this.

I have even heard of people using things like drano and other chemically hostile agents on old metal, though I haven't heard a lot of happy reports from those quarters. Electronic Cleaning is another magnitude of efficiency, at least for the restorer of ancient numismatics, which of course is the basis of this portrayal.

Be advised that almost all chemical cleaners are hazardous. Disposal is a real problem and is the Responsibility of the purchaser. Use only with extreme caution and foreknowledge, and have adequate safe disposal prepared for the spent chemicals. We recommend no chemicals for cleaning of ancient metals, and go so far as to suggest they be shunned completely.


Another big problem with using chemicals to clean coins is that once a reaction with the metal is begun by using a chemical on it, it is sometimes almost impossible to stop it, and there are well recorded incidents of accelerated corrosion in chemically treated ancient metal. This means that a year later the coins are in worse shape than before cleaning. Not a pretty sight.

The primary method for cleaning almost anything is soaking in water. For ancient metals its best if the water be as free of additives, like chlorine, as possible. Simply boiling water helps remove a percentage of its added chemicals.

Water is the most effective solvent on the planet Earth. Thats simply because there is so much of it, and its liquidity is assured within a fairly broad spectrum of temperature. Everything alive depends on the diffusivity effects of water on solids to live. Soaking your coins in water does not hurt them, provided the water is relatively free of chemicals, and tap water is usually OK, although watch for sulphur and silver!  They do not mix well at all. The longer coins soak, the more encrusted dirt will be loosened. That is the name of this game.

The problem with soaking is that to be effective the metal must be soaked long enough to penetrate to the metal core of the coin. On the average this takes several years. If the coins are soaked in anything, and only partially permeated with the water, any picking or brushing will have adverse effects. There are many coins that were only partially soaked, then brushed, so that the outer edges came clean long before the center of the coin, because of the increased angle of the brush at the edge. By the time the center of the coin becomes clean, the edges of the coin have been worn nearly flat with all the brushing. This totally detracts from the items value and can easily be categorized under the heading of Destruction.

There are many recommendations for coin cleaning that entail soaking in oil. This is risky business, and may introduce chemicals to the metal that are not good for it. Soaking in oil will not accomplish anything that soaking in water does not, and it adds the problem of removing the oil if that becomes necessary during further steps of restoration. Oils can sometimes be removed with detergents, but again, that means more chemicals to upset what has become, over 2000 or so years, a rather tenuous chemical balance. It is our suggestion that water be used in lieu of oil, and that you preclude all use of any oils in treating your coins except perhaps for some very esoteric circumstances during the finishing process. Olive oil in particular is extremely acidic, and etches ancient bronze destructively.


Picks and Brushes

The most important of the mechanical cleaning processes are the use of picks and brushes. The use of picks and brushes, with the emphasis on Picks, is what sets the restorer away from the novice. Conservation of ancient metal is Care to Detail. Meticulousness.  This is made easier with electronic cleaning methods, and the two fit together like hand and glove.

A pick is usually a pencil shaped piece of wood or plastic, with a rounded point on the ends. Occasionally a sharper point is warranted, and most picks are easily sharpened with a knife, pencil sharpener or by grinding on pavement.

Another common shape for a cleaning pick is the spatula shape,where one end of the pick is flattened. Imagine a worn regular screwdriver head, but plastic. Round pointed picks reach the places that spatula ended picks cannot, and very Pointed picks are only for hard-to-get places on the coin, like between designs or letters, or around the edges. Plastic picks are easy to obtain and are very inexpensive. Many can be culled from junk bins at thrift stores. The best are made from a hard type of plastic, which is still somewhat flexible. Good plastic picks wear from abrasion on the coins, and will need to be replaced regularly as they wear and are sharpened.

You will get to know the better plastics for coin cleaning by experimenting with as many different types as you can lay hands on. This is easy and inexpensive to do. Any somewhat flexible and hard plastic that will wear against the metal makes a good plastic pick. Nylon knitting needles offer the coin conservator interesting possibilities, as do certain pieces of barware used for stirring drinks.

The classic numismatic cleaning pick is bamboo. Bamboo has been used for this purpose for years. Bamboo skewers that work perfectly for ancient coin and metal cleaning can be purchased at any hardware or grocery store. Chopstix make great bamboo picks also, and are of greater size and strength than bamboo skewers. Bamboo is excellent because as it wears it develops somewhat of a "Mop" tip meaning the end/tip becomes squished out, and retains water well, which is a good thing.


When using plastic or wooden picks on a coins surface always keep the surface you are working on wet. This can be accomplished by dipping the pick in water and transferring water in drops to the surface of the coin. You want a wet slurry on the coins face while you are working; the wetness will decrease the chance of scratching the coin with an adherence on the end of your pick.

Easy Does It when using picks to clean coins. You can damage coins with picks too, and its a fine line, which basically depends on the material of the pick, and the make-up of the coins surface. Many times strenuous force is needed to get real hard corrosions to pop off, but there are some coins which are "Mushy", and when that type of strenuous force is applied, the surface actually becomes deformed. Thankfully this doesn't happen much. Fingernails and skin are quite a lot softer than metal, and can be used effectively in some cleaning processes, to good result.

When cleaning with picks use a back and forth, or circular motion, lightly at first, and only increasing force where needed. Again, nine times out of ten you will want to keep the artifacts surface wet. There are two basic ways to hold a cleaning pick. One is choked up, with fingers down near the point...this gives you a lot of control and energy down at the point...the second way of holding the pick is out near the end...this comes in handy under certain circumstance when a spring kind of action-energy is required to remove small and tenacious objects of encrustation.

All this brings us to another method, or sub-method of using picks to clean coinage. The function of leverage in the use of picks to clean coins is a circumstance with a lot of variety, and needs to be studied and experimented with. Many times the coin is put on its edge, while forceful downward movement is applied to the tip of the pick. This tends to pop encrustations off en masse, and can be used to penetrate deep detail, although this can damage coins which are mushy or cracked. Forward pushing motions of the pick, on a coin lying on its surface, are another form of leverage, and can be used effectively in many instances.

After initial cleaning with the picks, further rinsing can take place, and brushes, even an old toothbrush will do, will further aid the final removal of grime and encrustation. Brushes are not recommended for most cleaning but are very good to have around when they are needed. Brushing is most advantageous after picking of the metals surface is completed, or near complete.

Picking is, for the most part, the largest of the cleaning process.  It is recommended that all corrosions be removed by picking and brushing before the coin is finished. If corrosions are left on the coin they will eventually begin their chemical processes again, and spread; and as has already been mentioned, its even possible that they will be accelerated, if they are not entirely removed from the coin. Much of this process will become clearer to you, dear reader, as you progress through the next chapters.    It would be best if you read this in its entirety, twice even, before beginning your experiments.

Tumbling and Polishing

We have reports concerning degrees of success using tumblers to loosen dirt on coins or other metal artifacts, prior to secondary cleaning. It is something to think about although most forms of tumbling are abrasive, and it is suggestedthe restorer of ancient metallica stay as far away from abrasion in coin cleaning aspossible. As to the tumbling machines themselves, and their processes, the more passive vibrating tumblers are by far more desirable than the rolling drum type, for metal cleaning anyway, because the rolling drum can become a very strenuous environment once some room is made inside of it by the wearing down of the load. It doesn't take long at all to over abrade the entire load if something should go amiss. Finally, I recently heard of a buddy using an ultrasonic cleaner to remove the primary layers of dirt from unlceaned coins, and he happily reports that it worked well. He simply used water with no chemicals as his fluid. The ultrasonic cleaner is the type of cleaner used to clean fine jewelry, and the like.

Electric Wheels

Electric polishing wheels can be made from small electric motors. This can be very dangerous though, so only undertake a project like this if you are experienced in mechanics and electronics. Safety First. Always. These wheels can help finish a coin, or get some of the more obvious corrosion film off it. A low speed is best. These are not really good tools for the restorer of coins, but occasionally they can be used or are needed, though those cases are fairly rare. If you use a wheel get"Muslin Stitched" wheels, and any abrasive bar by which to charge the cloth wheel should be the least abrasive available. Usually you are looking at grit sizes whose numbers get larger as the grit size gets smaller. Talk to the salesperson at the hardware store where you acquire your supplies, or get books concerning metal polishing on wheels.These tools are actually overkill in many ways though, and just one nice coin being thrown by the wheel will make you rethink your needs this way. Anytime an electric device is turned on in a shop, it is mandatory that safety glasses be worn. You cannot clean coins without your eyes. Finally, remember this: over-polished coins are not as desirable as natural looking coins with somewhat of a dark patina, because the alterations are easily noticeable...nobody really expects a shiny 2000 year old coin, except maybe gold, and a presentation of such is always viewed with a healthy skepticism.


Electronic Cleaning



The act or process of chemical decompostion, by the action of Electricity; Websters International Dictionary, 1902

Passive Electrolysis

Electrolysis is an act of nature. There are electrolytic happenings going on all around us all the time. Any metal immersed in water is acting electrolytically, and every battery that you use to power a machine or utensil is just a prepackaged electrolyte reaction. The first electrolysis operation we will begin with is very basic, and can be considered a passive form of electrolytic cleaning. It utilizes certain natural phenomena that will allow you to bypass the necessary soaking time of several years in water before being able to profitably clean your ancient coins.

If bronze coins are put in a stainless steel container, then covered with lightly salted water, a natural electrolytic reaction will begin whereby electrons from the bronze will migrate to the solution...this take several months but sharply decreases soaking times in just water. Of course once the outermost layer of the bronze begins to move, all the dirt and encrustation between it and the steel turns simply to mud, and is easily removed with picks and brushes.

     There are products on the market likethe Maggie Pan, or Silver Lion, that work the same way for silver. They cause a natural electrolytic reaction to take place between silver and and the material of the pan. These can be had at any hardware store. They take awhile, and certain subsidiary chemicals are inherent to the process, most notably dish detergent of a certain type, but there is nothing too hazardous about those chemicals, and they do work just fine for passive electrolytic cleaning of silver.

Battery Electrolysis


The best way to speed up the electrolytic cleaning process is with electricity. This can be done several ways and each will be explained here. To get you used to it it is suggested that you start with a small battery, 1.5 volts will do just fine, and a stainless steel paperclip. Paper clip must by stainless, and that is the only thing that must be absolutely adhered to, or the reaction will not work correctly.

Find the positive and negative sides of the battery and attach small diameter copper wires to each end, about 12 inches long. You can tape the wires on as long as the connection is good. The thickness of the wire should be about as big around as a straight pin, or smaller.

Next get a glass jar (Pint or Quart) and fill about 2/3 of the way full of warm salt water. The amount of salt is not too important but try to keep it around a teaspoon per quart.  It needs to be "In Solution" so stir the warm water until the salt dissolves.

Now take an uncleaned coin and "Wire it" by wrapping some copper wire around it a few times so it is in its own wire basket. Make a loop at the top of this wire basket and attach that loop to the wire coming from the negative side of the battery. Of course you need wire against wire so that electricity flows. This may entail removing the insulation at the ends of your wires if the wire is plastic coated. Many times this can be accomplished with a lighter. Heat the end of the wire until the plastic starts to bubble, wait a few seconds, then pull the insulation off. Be careful not to burn yourself. Rubber gloves are nice and should be worn throughout the entire operation, if possible.

Next wire the positive wire from your battery to the stainless steel paper clip. Twist the positive wire from your battery around one end of the clip.

Now immerse both in your glass of salt water. The wire holder and the coin will begin to bubble immediately. The bubbles will be very small. If the paperclip is bubbling the polaritys are reversed on your wiring.  After about an hourof this treatment, maybe more, maybe less, depending on the size of the coin and the power of the battery, the coin itself will be bubbling over its entire surface. When it appears that bubbles are coming from the entire coins surface, that means the coin is conducting electricity. Electrons from the coin are going into the electrolyte (Salt Water). As these electrons move they totally loosen any dirt or encrustation between the surface of the coin, and the solution.    The hard caked on dirt of the ages has now been turned to mud. You can then pick and brush the coin without damaging it, and all the dirt will have literally become separated from the metal.


Transformer Electrolysis

To further empower an electrolytic reaction/cleaning process, all that is needed is a more powerful source of Direct Current Electricity, from a transformer. The small black transformer units (AC Adaptors) that plug into a 120V outlets, which supply power for things like telephones, answering machines, and computer printers are ideal for this purpose. These are readily available, and inexpensive, at any fleamarket or thrift shop, and I think its safe to say that many of you readers probably have a few laying around the house, orphaned from a piece of equipment that ceased to function. Most of these types of plug-in transformers are DC, Direct Current, and that is what we are after. Read the label and make sure though, because there are a few made whose output is odd, like 3 volts AC. Get DC, and use voltages between 4-8 volts, for most operations. Even if you decide to do multiple coins in mesh baskets later, its not the voltage you will want to increase, but the the current, the amperage. The Current is usually measured in milliamps, 1000ths of an amp, and there are some of these small transformers rated up to 500 milliamps or higher, which of course is half an amp or higher.

Be Careful.

If you try to learn to only touch the electrical work with one hand at a time, you reduce your risk of getting hurt by electricity by 90% or more. These currents and voltages are minimal, but you can get shocked, and thats never pleasant.  Usually its a short from the AC side that hurts the most, and that will get your attention 'bout quick.

These small plug in transformers come in a true variety of shapes, sizes, and values. You are looking for something from 4-8 volts DC, 100 to 400 milliamps. Anything in that spectrum will work fine for a quart to 5-quart bath.

Once you get a suitable transformer (I like 6-8 volts, 300-400milliamp) clip the plug off the end of the transformers output wire, which is the wire you actually plugged into the original device to make it work. A pair of scissors works fine for this. Then separate the two output wires by pulling them apart. Separate them down the wire about 8-10 inches or so. Sometimes there is only one wire evident during this operation, and in that case it needs to be stripped, and there will be two wires inside the covering. There has to be two wires, even if one is very thin. The transformer, of course, should be unplugged during all the above operations, and not plugged in at all until everything is in place.

Next, obtain a 1/2 gallon or so Plastic or Glass container and fill it about 2/3 full of salt water. Warm water is better, but not entirely necessary. Add about 1 teaspoon table salt per quart of water, and stir so that the salt dissolves, going into solution. This is your electrolytic bath, the electrolyte. Plain table salt, iodized salt, works best. The saltwater solution, the electrolyte, will get very cloudy as the process components  spend themselves, and again you should prepare against this with rubber gloves. Here is something you need to know when considering safety first:

***From Popular Science Library, Electricity and Magnetism, Copyright 1922: "...The manufacture of many of the caustics....are a phase of this art" (Electrolysis).  Caustics are corrosive and will burn your skin.

Wear Gloves, Be Careful.

Now instead of a battery as a power source, you have the transformer. You will want to hook up the positive side of the transformer wire to a piece of stainless steel, like a butter knife; again, this material MUST be stainless, and stainless butter knives can be had surplus at all thrift shops for about 5 cents each. It is good that these are plentiful, and cheap too, because they eventually dissolve during electrolytic reaction. If you can't tell which is positive, and which is negative, it is easy to see once the power is turned on.  If the coin holder/coin is not bubbling but the butterknife is, just reverse the wires from the power source to each.

Now repeat what was done during the battery experiment, but instead of using the wires that were attached to the battery, you will be using the wires coming out of the 6 volt transformer.

I usually just strip the plastic coating from my wires, about two or three inches off the ends, then twist the bare wires around the stainless object I am utilizing (The butter knife), and the wire basket of the Object to be cleaned. Alligator clips are handy to have around for jobs like this, too, although they eventually get pretty cruddy, and will break. Try to keep the connection (Where you have twisted your wires together) out of the electrolytic bath.  It will last longer that way.  Whatever metal hits the bath is going to get chewed.

The coin, or object to be cleaned, now gets attached to theNegative end of your power source. When the stainless steel and the metallic object being cleaned are immersed together in the salt water solution, NOT TOUCHING each other, anode and cathode are created, in electrolyte, and all that that portends. When electricity is applied, by plugging the transfomer in, a healthy current begins to flow between these two electrical entities, through the electrolyte (Salt water), and quite a number of things begin to occur simultaneously, one of those things being the cleaning of your coin or artifact. Electrons are being swapped about all over the place! Once this operation is going you must always think Safety First! Though chemical free at the outset, the process will eventually render its components into new and possibly harmful materials.

One of these by-products produced during this type of operation is Hydrogen Gas.


There is sodium and chlorine going on too, so watch it. Rubber gloves really are a must.

There is not a whole lot of Hydrogen that is being produced at any given time, and good ventilation is enough to easily overcome the dangers of fire, but NEVER do this in a closed room, and always be VERY aware of accumulations and the possibility of explosive fire and noxious fumes. No Smoking    Use the same caution you should use every time you put gas in your car, and you will be fine.

Pre-wiring of coins or artifacts with a single strand of stripped copper wire, making a sort of a mesh basket out of the wire, is a very good idea and will make your cleaning operations expedient and productive. Twist-wire this"Assembly" to the negative wire of the transformer, and the piece is lowered into the salt water bath. Small tent clips or alligator clips are handy here also, to keep the wires in their places, clamped to the side of the jar. Once all this is done its time to try it out by plugging it in.

Again the wire holding the coin or artifact being cleaned should begin to bubble immediately. These bubbles will be very small.

And again, finally, if you put the power to the bath, and see the piece of stainless steel bubbling, instead of the coin or the wire basket, you have the polaritys of the dc power source backwards. Switch the leads and everything will be fine.The coin or its holder will begin to bubble, and you will have begun your quest toward professional metal restoration and preservation.

Electricity is now passing between your coin, and the butterknife, through the solution. At the surface of both the coin and the knife the molecules of salt and water are being changed by losing or gaining particles, and so are the stainless steel and the artifact.

Once current begins to flow through your artifact, the very outermost metallic layer of the entire object starts being spewed off through solution to become part of this orderly and intricate electrical dance. Sometimes it takes a little while for the artifact to begin to conduct, depending on how badly encrusted it is, how tight its wire wrap is, or what type of patina/reaction shell encases it. Once your artifact begins to conduct well though, its not long before it should get pulled, because this conduction will loosen up EVERYTHING between the metallic surface and the solution, meaning encrustations, plain dirt, and the like. Once the initial molecular layer of metal begins to move off the entire artifact, the rest is overkill. Many times though, it will appear as if the coin is conducting well, but the really tenacious flakes or deposits will remain after removal from the bath and the picking/brushing/drying stages. It is generally a good idea to re-immerse these unless the leftover detritus can be removed by dry picking, or other means. Re-immersion is the rule, and to get the corrosions off in any other way is true rarity. There is one trick beloiw, in the trix section, that might come in handy along these lines, the use of epoxys, but that is chancy and should only be tried on specimens you are not afraid to damage.

Many times when multiple coins are being cleaned in each pot there is a cycle that develops, whereby half or more of the coins get shunted back to the bath. This method is highly preferable to over cleaning. Over Cleaning should always be avoided.

Here is the Number One Rule of Electrolytic Cleaning:

Monitor Constantly and Check OFTEN.

You will learn to recognize various stages of the cleaning process after you clean 50 or 60 coins. Different patinae act differently too. The only way you are going to get it is to Monitor Constantly, Check Often.

The best sign that your artifact is conducting is if it Itself is bubbling, as well as the wire it is wrapped in.

If your bubbling ever stops that means the operation is not doing what it is supposed to. Something is wrong. Most common causes are deteriorated stainless steel, a bad connection at the stainless piece, corrosion of the transformer wires at the bath, or a problem with the power supply.

Sometimes it helps promote cleaning to add small amounts of salt, and it is not a bad idea to add a little salt each time you add water. You will have to add water regularly as the solution is transformed. The pots can be kept going for hundreds, maybe even thousands of cleanings, by just adding saltwater when the solution level drops. Remember though that the more cleanings that take place, the more free metal salts and other transformed chemicals like sodium and chlorine (Table Salt) there will be. Disposal is the responsibility of the creater, and should not be looked upon lightly. The best way to dispose of the spent solutions is to make a settling tank out of a small plastic drum. Allow the top to be open and let the fluid from the spent chemicals dry to a solid. This can be dumped at landfills after informing the attendant of its origin. They will instruct you from there. Its possible the solid waste can be boxed and bagged and discarded as regular garbage. But be careful you might be throwing away good things. Check with refineries in your area. They may be willing to buy the solid waste of the electrolytic cleaning process. There are a lot of metals present in this solid waste that can be used further, and possibly for profit.

In a professional electrolysis set up there are usually at least two pots running, as well as a fan, which cools the transformer power supplies (one for each pot), and also ventilates the work area; There is also a toaster oven, and a warmerplate (More about these next). These all get plugged into power strips, the type with 6 outlets are very good because the transformers are bigger than a regular plug of course,covering usually at least two of the outlets in any power strip. Everytime the transformers are on, at least one small computer fan is running too, whose airflow is directed at the power supplys, for cooling purposes, and at the electrolysis pots, to disperse gases. All professional electrolysis work is done out of doors, like on a screened-in porch. Warmer plates can be used to keep the electrolysis pots at about 100-120 degrees, which helps the solution work better. Not necessary, but its a trick that will speed things up a little more if needed. Most if not all of the Spanish shipwreck treasure salvaged from Florida Waters has been cleaned electrolytically. It is a time honored and very effective methodology.

It really is vital to cool these small wall unit power supply transformers. They will burn out quickly if not auxiliary cooled. Many only last for several dozen coins before burning out if not auxiliary cooled. If the fan is used to cool them during operation most will last through thousands of cleanings.

The electrolysis process of cleaning metals is by far the easiest and most effective method for preservation of numismatic metallica. It is another magnitude of efficiency, especially when considered against harsh and dangerous chemical treatments. Except for very odd circumstances it can and should be used exclusively for cleaning iron, brass, bronze, steel, copper, silver, and gold.



The Toaster Oven

The use of Heat is a bona fide electrical aid to cleaning metallic artifacts. It should be used in conjunction with electrolysis, and after electrolysis. There are a few tricks to know about heat that will make your coin cleaning more productive.

Once a coin has been cleaned it needs to be thoroughly rinsed then thoroughly dried to see the contrasts of places that have been missed, and to halt any reactions that water might precipitate. This is best accomplished with a heat source such as a toaster oven. The toaster oven is an all around metal cleaning tool, and they can be obtained very inexpensively at any thrift store or fleamarket. Every good bench needs one. Be careful and respect it though. It will burn many things, you included.

There are many instances of coins that have cleaned up nicely except for perhaps a spot or two of hard reaction shell patina that would just not popoff. Before attempting heavy duty methods, or re-immersion in the bath, something that works fairly well is to take a coin like this and subject it to high heat (300-400 degrees), then immerse it in ice water right from the oven. Many times this will loosen the tenacious flakes of patina that were not removed in the bath.

Both high and low heats can be used for various things when cleaning and restoring metallica. Heating below 500 generally cannot hurt the metal, and many times it actually restores the original color/patina-look to the coin, darkening the old metal without chemicals or other artificial means. If you get an oven with a metal top it makes a great drying table in between stages of cleaning also. As has been stated, a lot of time during their cleaning, coins need to be dried, because any left overshell/patina will many times show up on a dry coin, that you cannot see when the coin is wet. You would not want to finish a coin that still has patina on it. To arrest corrosive reactions, all previous corrosion needs to be removed from coins that have been buried.

Other than removing the old patina shells electro-chemically, Dry Heat is the main tool used to arrest corrosion. If the corrosions are extremely detrimental and destructive, the best thing to do to keep the process from beginning again, is to heat lengthily, and then coat with an airtight finish.

This is not a guarantee that corrosion has been arrested, but it is really the best you can do. Many times it takes years to see if a treatment not only worked, but held. many archaeologically restored coins of 20-30 years ago, the types impregnated with chemicals, did not seal the air from the metal and are now just blossoms of metallic oxides.   Its always good to take photographs of coins, even during the process, and especially finished products.

The Romans in particular silvered a lot of coins by a depletion process, whereby silver was added to the copper alloy, like 5% or more, then the flans/planchets were immersed in a light acid that selectively etched only the copper. The hammered surface of this type of coin appeared silver (until worn) because the hammering action created a semi-permanent weld of the silver deposit at the surface of the coin which was left as detritus after the depletion acid bath. Many times a"Repletion" effect can be observed on these coins after electrolysis, especially if the coins are subjected to high heat, say 300 degrees+ for several hours. It doesn't work on all of them, but some of the results are surprising.  After this process finishing with rubber (See Below) worx well many times 2.

Finally. Electrolysis and heat as electronic cleaning methods for coins are the most preferred for their overall comprehensiveness, and ability to halt and arrest ongoing reactions that, if left unchecked, would fully obliterate numismatic record in as few as 5 millenia.



Beeswax, Pine Resin, and Plastic Coatings


On fine and whole coins with no problems it is best to apply a thin coat or two of clear acrylic spray after cleaning and heat treatment. If the coin is well patinaed and not cleaned electronically it is also best to use acrylic spray. Most of the sprays can be removed with acetone later if they need to be. This clear spray tends to lighten the coin up a little, so if the coin is too light already, think twice before spraying it. Or put heat to it longer to darken it up. Do not spray coins when they are hot because the plastic spray will harden before bubbles get a chance to come to the surface and it will foul the finish. This type of spray is usually very flammable and not good to breathe.

On coins that have had problems, like pitting, wear, broken, or too light, a good finishing treatment is beeswax applied during the final heat treatment. This soaks into the porous metal and seals it somewhat, also smoothing out discriminations in the surface a little. It can be lightly polished with paper towel once it is dried and hardened, and it will still keep its color. You need to wipe the hot wax off the coin as soon as it comes out of the oven, which means Wipe It Hot, and that will impose certain logistics upon you concerning your preparation. Beeswax is very reasonably priced and readily available. It is perfectly safe to use. The only drawbacks to wax is that once its used it is the devil itself to remove, and it is not a perfect seal on porous metal, and may allow further oxidation, corrosion, in the future. I have sprayed over coins that were treated with beeswax, after making sure any excess wax is removed, and they seem to be very presentable and are effectively sustained. You have to experiment and see what works best for you.  Pine resin can be used instead of beeswax, or in conjunction with it. It is best to experiment on lesser coins if you are unfamiliar with a process, and learn from there.  Beeswax is virtually unremovable though, and does not seal air as well as removable plastic spray finishes.  Eitherway, these three finishing processes will not harm cleaned coins, and can be further modified if the results are less than one had hoped for. As a rule, stick with spray 99% of the time or more, because it seals the air out, and is easily removed in the event a future numismatist finds it necessary to do so.

There are other finishing treatments too, though they become more specialized and expensive, and dangerous to use. Many times exotic finishes preclude a natural look, and serious collectors wish to obtain only coins with darker finishes, in as natural a state as possible.



Dud Coins

Hopefully you have been saving your dud coins too...most of that will be copper, but there will also be some silver, and traces of gold, because of the primitive alloying process. Here we cite The Popular Science Library from 1922, (This refers to the amount of trace precious metals in natural alloys in MODERN Times!):

"...The statistics in regard to copper refinement for one year are as follows: During the electrolytic refinement of 279,000 Tons of copper, the by product of precious metals that were recovered was 27,000,000 ounces of silver, and 346,020 ounces of gold."

This means that the earlier smelting and refining processes,which many times used metal straight from the mine, were incapable of removing these traces of precious metals, and a lot of the natural copper and other metals from earliest times are mine run metals and have varying percentages of gold and silver in them. This can be sold for profit by the astute coin cleaner.  Electrolytic refining is an art unto itself, and nearly 100% efficient, as opposed to ancient refining methods.

By dud coins it is meant cleaned coins that are flat or irretrievably broken or corroded. No information. If you are buying uncleaned ancient coinage now, you need to electronically clean even the groatiest of coins you buy, because even some of the most unlikely pieces turn into jewels once their shell is removed.

A trick when using electrolysis, especially when you have coins in the bath for their second time, is to turn the process off for an hour or so, and let everything cool down. Then restart the process by turning on the electricity for about 10 more minutes. This will many times remove or loosen really hard spots of corrosion that would not budge from the coins surface previously.

Other Trix

When wiring a find onto the negative end of the transformer, it is many times advantageous to pre-wire the coin or artifact, then hook up the transformers wire to that. Single strand copper wire of fairly sturdy grade, again, about the diameter of a straight pin, is best, and it can easily be wrapped around the coin 3 or 4 times so that it is in its own little wire harness, or basket. This method can be further modified to incorporate many coins at once, although time in the the solution will be increased the more coins you add.

One of the best last-step cleaners for ancient coinage, silver included, is non-abrasive pencil eraser, gum rubber. It takes a lot of pressure, but works well in some areas, and it is the least erosive of mechanical methods of cleaning. Pencil erasers can be added to chopstick picks and the tool becomes not only dual ended, but dual purpose too.  Erasers that are used to remove ink are a no-no when cleaning coins. The abrasive in them will mar a coin every time.

References are made by Gerhard Welter concerning shock treatment of metal, to "Dis-Adhere" patina or reaction shell from the surface of the coin. This occurence is easy to observe when attempting to straighten bent coins. The two ways to straighten bent coins are hammering (Use leather and plastic pads between the surfaces and the coin) or by squeezing in a vise/press, again between two heavy but sympathetic materials. Where the coin gets re-bent to shape, the patina or antique finish gets crackled off the metal most of the time. This could be helpful in loosening coins that have become corrosion-welded together, also.  Heat and Ice treatments have worked on corrosion-welded coins before too.

Here is a fool proof and easy way to clean all coins, even American Coins dug from the Earth. Put the coins in a pan that drains and will not corrode, ceramic is best, and put that on your roof and forget about it for a couple ofyears. Maybe longer, maybe not quite so long, but for a good while. Put it where the sun can get it regularly....that is a long term erosive force. Many time surface finds are extremely clean on their "Up" side, but still dirty from being buried on their underside. This is easily observable and has been noticed by many. The cleaning of coins and other metals by exposure takes a lot of time, but there are some things found here that cannot be cleaned in any other way without drastically reducing their value. There is a story of an Irish farmer finding a large  corroded/encrusted ring of metal while plowing one day.  He hung it in a tree, thinking it was a defunct farming part, and wanting it out of the way of his machines discs.  About a year later he had occasion to visit that tree again, and happened to look up, to see a beautiful Druid gold torc, which in the year it had been exposed to the weather, had "Worn" back to its natural state, and was perfectly clean.  All without chemicals or other treatment.  The weather is a powerful force and can be put to work to your advantage.

One way to remove otherwise irremovable encrustations, or to remove just minor encrustation on an otherwise nice coin, is to coat the side that has the encrustation with a plastic epoxy adhesive, and let it harden. After it hardens carefully pry this epoxy layer off the coins face, and many times it will remove loose encrustations. I have been pleasantly surprised at the results of this method many times. I usually make the epoxy more a droplet than a coating, as it provides greater solidity during removal.

Reaction Shells (Patinae)

The Restorer of ancient metals will eventually begin to recognize the gargantuan force of time by its look. There are many aspects to the look of the ages. Different visual input can clue the discerning observer to certain traits that will allow greater utilization of time and resources.

Coins that are heavily coated with dark brown patina seem to be the best as concerns state of wear. Some people call this "Black".  There are a higher incidence of Mint/NearMint coins from metal encased in that type of shell. Sometimes it is true aggravation to get the conduction going with them, because that particular coating can be hard, but once it starts its done quickly and the shell of patina falls right off in flakes.

The next best look to many high grading conservators is the dusty brown/tan that appears frosted onto a coin. You could brush for days and just get about half the compacted dust off those coins, but that type of reaction shell hides a great many near mint state coins, and nobody can know until they are cleaned, because usually there are no visible surface details at all.

The green copper oxides seem to be the most destructive of all the patinae, forming lots of pits. Green encrustations (Bronze Canchre, Cancre, copper chlorides, etc) are the worst thing to see. If the coin is entirely enveloped in green,and showing good detail,   it is usually best to leave it as is, maybe spraying with clear acrylic, because the removal of that patina is actually a layer of the oldest metal, and you lose detail, and usually alot of it, when a nice total green is taken off the coin. The best way to rid yourself of all these coatings (Reaction Shells) is with the aforementioned electronic process of electrolysis, in conjunction with a well practiced regimen of picking, brushing, heating and finishing.
































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