Do-it-yourself restoration of copper coins. Cleaning (restoration) of found ancient coins. Silver coin cleaning
Cleaning coins at home is a simple set of works, the need for which is due to the oxidation of almost any metal over a certain period of time.
Those who know the specifics of various metals, in particular, copper, gold, silver, etc., are aware of the fact that the older the coin, the more oxides appear on it.
When cleaning coins made of copper and other materials on your own, without resorting to specialists, you need to follow simple rules to avoid damaging even the oldest coins.
Do we spend money on purchases or do we manage with handy means?
Specialized solutions intended for cleaning procedures were developed taking into account the specifics of each specific metal: copper, silver, etc. Each of the products presented on the shelves of hardware stores allows you to remove various dirt and uneven patina, oxides from the surface of the coins.
However, in an effort to restore copper and other metals to their original radiance and purity, not everyone can afford to purchase these rather expensive solutions.
Therefore, most ordinary consumers decide to tidy up the copper surface of the coins with the help of more accessible and less expensive means.
Alternative cleaning methods suitable for home use can clean almost any soiled copper coin.
The list of necessary funds available in most households is as follows:
- "Coca Cola";
- lemon acid;
- soap;
- electrolysis.
With the help of each of them, many ordinary consumers were able to clean the copper surfaces of coins and other products from this and other metals without undue hassle.
The algorithm for cleaning coins made of copper and silver is characterized by the same simplicity and accessibility as similar copper products. Numerous Internet resources contain all the necessary information.
The following review is dedicated to the task of cleansing copper coins different ways.
The preparatory stage is the search and selection of a container, the possible material of which is:
To clean copper coins, in addition to citric acid, you also need to prepare water. Acid is poured into the dishes and diluted with water. Coins are dropped into the solution.
It is necessary to take into account the rather strong aggressiveness of the solution - the cleaning process must be carried out under continuous control.
From time to time the product needs to be turned over. Carelessness and neglect of this requirement can lead to the fact that the solution can clean the coin down to the metal.
After it was possible to clean the entire surface of the product, remove the contamination completely, it is desirable to bring an artificial patina.
Option number 1
This cleaning technique is considered as soft and safe as possible for the item. As a rule, in this case, not household, but neutral baby soap is used.
Having decided how to clean the coins, the soap must first be grated on a large or medium grater. Then the grated soap is diluted with a small amount of water - until a homogeneous mass of a plastic type is obtained.
To clean the coins, they are inserted into the resulting soap mass. Leaving the products in this state for a while, however, it is necessary to periodically pull them out of the water and check, washing off the layers of dirt and oxides.
Having decided to clean coins with this method, it is necessary to understand such specifics of the approach as its impressive duration. The fact is that absolute cleaning in extreme cases can be achieved only after a few weeks.
Option #2 (optional)
You can also achieve the desired goal by resorting to laundry soap. The process is somewhat different from the similar one above, but just as simple.
In this case, a plastic container is used as a container. It is filled with boiling water, into which soap chips are poured.
After waiting for the soap to completely dissolve and a jelly-like substance is obtained, the owner can lower copper coins into it, leaving it for a day or even two. The duration of stay in the solution depends on the degree of contamination of the products.
After the required period of time, the money must be washed with a soft brush and dried properly.
Multiple repetitions of the procedure are allowed. By removing all oxides layer by layer, you can get coins with an absolutely clean surface without any damage.
Fizzy Coca-Cola: spend money to clean
The ambiguous properties of the drink, beloved by children and adults, have also found their application in the struggle for the purity and radiance of voiced coins.
Many already know that it can be used to perfectly clean and polish the chrome surfaces of various products. No less successful is the cleaning of old coins at home.
So, in order to clean a dirty and tarnished coin, it must be lowered into a container, preferably glass, and filled with sparkling drink. The dishes and their contents are left in this state for several days, best of all - for a week.
With a lack of patience, the time required to clean the coins can be significantly reduced. To do this, the dishes are placed on a radiator or other safe and efficient heat source. The essence of the approach is that an increase in temperature accelerates the reaction.
It is possible to tidy up an old coin in the presented way due to the content of a small amount of orthophosphoric acid in a sweet drink. If the pollution is much more serious, you will have to turn to more radical methods.
Those who paid due attention to the physics lesson are familiar with this concept from the school bench. Its usefulness in the processing of coins will be ensured by observing the following two important rules:
- compliance with safety regulations;
- testing the method on inexpensive specimens, in order to avoid damage to more valuable products.
Costs Special attention to give the second point to the principles of work: the fact is that sometimes, due to a minor mistake, serious, irreparable harm is caused to a coin or other valuable product.
Old coins are restored in terms of purity and brilliance by using a small power supply (6-12 volts). As such, universal charging can be used. Another alternative: an old mobile phone charger.
Attached to the power supply or its alternative:
A saline solution is also used, prepared in the following proportions: 1 tablespoon of salt per 1 liter of water.
The process is simple, you just need to accurately follow all the steps. One clamp - with a minus sign - is attached to the specimen, while the opposite one - with a plus sign - is attached to a metal object.
Then the coin and the metal product are lowered into a pre-prepared container where the brine is located, while the power supply is plugged into the outlet.
The result makes itself felt quickly enough: the process of dissolving oxides and dirt leads to a rapid clouding of the solution. The “bathing” period is short, after which the specimen is washed with hot water and dried.
A little care and clarity in the implementation of all steps will achieve the desired results.
Mix of soda and soap
If you want to achieve the desired cleanliness in the shortest possible time, then the soap method can be enhanced by using soda. However, you need to add soda already in dissolved form.
After completing the cleaning, the coins should be properly washed, after which they should be lubricated with alcohol and vaseline ointment. Last step provides maximum protection against the appearance of new contaminants and oxidation.
The oil method
In this case, you need to boil the coins in the oil. The best option: the use of vaseline oil. The boiling process must be brought to the absolute purification of coins. The last step: washing in ethyl alcohol.
Edge cases
If the coin is brought to an extreme state: it is unusually heavily soiled, caustic soda can be resorted to. Handle the product very carefully, it must be diluted in cold water.
Since this product is inherently a strong alkali, it is recommended to avoid contact with it. You need to lower the product into this solution using tweezers. The residence time in the solution: no more than ten minutes, after which the coins are taken out and washed.
However, not all coins can transfer this method. If a spot of green or blue color is noticed on their surface, the cleaning process should be interrupted. In case of a negative reaction, do not use this method on already tested products.
Having studied all kinds of ways to clean coins and choosing the optimally acceptable one, you need to observe the accuracy of each step.
You also need to take care of your own safety - especially when using some methods.
Clean, shiny and sparkling coins please with their appearance both connoisseurs and connoisseurs of these products, and ordinary users who, for one reason or another, are interested in cleaning reused coins made of copper and other metals.
Mother of two children. I have been running a household for more than 7 years - this is my main job. I like to experiment, I constantly try various means, methods, techniques that can make our life easier, more modern, richer. I love my family.
Many collections have good coins (without mechanical damage), but with dirt or dark spots. The problem can be solved in various ways to eliminate external defects. We will talk about them in this article.
Types of coin cleaning
Depending on the degree of contamination, the characteristics of the material and other factors, it is necessary to determine the appropriate method. Among the main types of coin cleaning are the following:
- chemical,
- mechanical,
- cooking,
- electrolysis.
The chemical type of cleaning involves the use of ammonia, acids, soda, soap, detergents and washing powder. In the presence of concentrated hydrochloric acid, you can make a special bath with a solution and immerse coins there. After the procedure, it is better to rinse the coins with alkali to stop the reaction.
Cleaning warm soapy water suitable for most metals. You can fix and enhance the effect obtained with any dishwashing detergent, ordinary laundry soap will also give a good result. Coins with minor contamination should be soaked in the resulting solution for 2-3 hours. Coins with abundant coating can be kept in the prepared liquid for about a day.
How to clean a coin with baking soda
Soda cleaning is an alkaline method of removing dirt and is suitable for low-grade copper and silver specimens. The process is carried out easily, without creating special conditions. First, a slurry is formed from a spoonful of soda and a small amount of water, then the mixture is applied to the coin. Removal of dirt is carried out with an ordinary soft brush. Soda can also be used after acid cleaning to extinguish the reaction.
How to clean a coin with vinegar
Cleaning with vinegar or citric acid suitable for hard metals. A teaspoon of soda is added to the vinegar solution, the liquids are mixed. Coins are immersed in the resulting bath and remain there until the stains disappear, and then treated with soap, warm water and a soft brush. If the contamination is not washed off, the procedure is repeated.
It is undesirable to use this method for coins made of gold, silver or copper.
Cleaning coins by electrolysis
Electrolysis- the most dangerous, but also the fastest method of eliminating defects. Cleaning is carried out by applying current to a slightly salty solution of water with a coin placed there. We will talk about this method in more detail at the end of the article.
ammonia as a coin cleaner
Cleaning with ammonia is suitable for products made of silver, pure copper or alloys containing it. The coin is immersed in ammonia for the time necessary to achieve the effect, then removed and washed. The room in which such cleaning is carried out must be well ventilated.
mechanical cleaning
For mechanical cleaning, various objects and tools are used (drills, brushes, needles, scalpels, pieces of cloth, etc.). This method is quite effective and removes any contamination, but there is a risk of damage to the surface of the products.
Digestion of coins
When cooking, the coin is processed in a boiling liquid, you can additionally use oil (vaseline or olive).
Several coins are placed in a pot with hot oil for 10 minutes(it is more convenient to clean in a special lattice box on a chain). After cooking, wash the products with a brush and soap and remove the remaining oil by thoroughly boiling the coins in distilled water.
After cooking, the specimens acquire radiance and brilliance, but a noble patina comes off them, which gives the products additional value. It is better not to expose rare coins to such an impact.
Rules for cleaning gold, silver and copper coins
The choice of the optimal method is made taking into account the specific properties of the metal. Cleaning, carried out in the absence of the necessary knowledge and experience, will not give the coin its original appearance, but will significantly harm it. For example, mechanical action using asidol or jewelry paste leaves scratches and helps to erase small details of drawings.
Cleaning of gold coins
Gold coins do not need aggressive cleaning. If the products appear dirty, it will be enough to wash them with warm soapy water, rinse with water and dry. Do not rub gold coins intensively, because even ordinary fabric leaves on noble metal small scratches.
Cleaning silver coins
Choosing the right cleaning method for silver items depends on from the sample and the degree of oxidation of the metal. High-quality silver coins can be cleaned by placing them in a solution of ammonia (10% ammonia and 90% water) for an hour or in a soda solution (30 g of soda per 100 ml of water) for several hours. The process will be accelerated if the liquid is brought to a boil several times, and the oxidized areas are treated with a soft brush.
High-grade coins with slight traces of oxidation are best cleaned with a mixture of toothpaste, ammonia and baking soda. The resulting mass should not contain abrasive particles. The coin must be covered with the mixture and rubbed with fingers or a brush.
Suitable for cleaning low-grade silver coins Trilon B solution. When the green layer comes off the surface of the coin, you can continue the process using a special mixture for silver of a certain sample.
Cleaning copper coins
Copper products are subject to the formation of a layer of patina on the surface. If there are no signs of corrosion on the coin, and the film is uniform, then it is better not to take risks and not expose the copy to cleaning. Patina protects metal from corrosion and gives the coin a noble appearance. To eliminate traces of touch and grease, the product can be washed in warm water.
Coins that have undergone corrosion are best cleaned using aggressive reagents (acetic and citric acids, Trilon B). They will gradually separate the damaged metal layer, without affecting the solid base. To process slightly oxidized coins, soaking in solution for several hours will suffice, while heavily oxidized coins can be left for a day or more.
Bronze coin cleaning
Bronze products are cleaned according to the same principle as copper ones. But keep in mind that ammonia changes bronze color. The metal may turn brown or even black. The shine of a bronze coin can be easily restored by applying toothpaste to its surface and washing it in warm water. Dry the products after cleaning by wrapping them in two layers of a soft cloth and a paper towel.
Sulfuric and nitric acids should not be used to clean copper or silver coins, as they destroy the fine details of the pattern.
Coin cleaners and tools
In addition to the above methods, there are others. Tools that are suitable for cleaning:
- toothbrushes of varying degrees of softness;
- wooden toothpicks;
- brush with natural bristles;
- plastic utensils, tweezers;
- reagents (soap, distilled water, soda, linseed and vaseline oil).
Rare and valuable coins It is not recommended to clean it yourself - professionals will do a better job. The following cleaning methods are suitable for dug metal. The main goal is to preserve the patina when cleaning, removing all unnecessary oxides. Before processing, the coins are washed with soap.
The best safe way to clean coins
The simplest and safest method is using laundry soap. Boiling water is poured into a hermetically sealed plastic container and grated 72% laundry soap is poured.
When the solution thickens, coins are placed in it. After a day or two, the coins are removed and rubbed with a toothbrush with trimmed bristles. The procedure is repeated until the desired result is achieved. Some oxides can be carefully removed with a wooden toothpick.
The disadvantage of this method is that it takes a lot of time, but its undoubted advantage is that the extra layers are removed gently and gently.
Exposure using caustic soda is very fast way but fit not for all coins. Both products with a relatively even field and with an uneven thin film are cleaned well.
In the manufacture of caustic soda solution, safety precautions must be observed. Dissolve granules (1 sachet per 500 ml) only in distilled cold water, take a coin with tweezers and be sure to work with gloves.
The product is immersed in a solution for 10 minutes. Then washed with water. The softened oxides can then be easily removed with a brush.
If during the cleaning process the oxides on the product become blue or green, the process must be interrupted immediately.
Cleaning copper coins
Careless cleaning of a copper coin can cause chips and pits to appear on its surface. Depending on the type of corrosion, the appropriate method of exposure is selected. Reddish plaque is removed with a five percent solution of ammonia or ammonium carbonate. The coin must be held in ammonia solution no more than 1-2 minutes. Green plaque can be removed with a solution of citric or acetic acid. A yellowish coating is dissolved with a 10% solution of acetic acid.
After cleaning the coin by any of the above methods, it must be boil in distilled water. After several boilings, you can check whether the coin is completely cleansed by dropping a 1.7% solution of silver azonic acid into the water. If after that the water remains clear, then the cleaning process must be completed.
After cleaning, the product must be thoroughly dried. You can place a copy in a special drying cabinet for two hours or dry it in acetone, and then in alcohol (no more than an hour).
If the natural patina on the coin could not be preserved, can be artificial to give the product an attractive appearance. 50 g of copper sulfate and 5 g of potassium permanganate are added per liter of distilled water. The resulting solution is heated to 80-90 degrees. Coins are placed in the heated liquid. Next, turn the coins over from time to time and wait for the desired color to appear. After the procedure, the coins must be dried and covered with a mixture of alcohol and benzene 1: 1 to protect against corrosion. You can also read about artificial patina in the article ""
Electrochemical cleaning
Electrolysis- fast and effective method remove dirt, but its use is associated with some of the dangers inherent in the operation of any electrical appliance. The device must be used in a well-ventilated and well-lit area. Before carrying out the process, be sure to wear protective gloves and glasses.
When using electrolysis, the risk of damaging a coin increases significantly (by several times compared to other methods). Assembly requires a power supply with voltage 6-12 volts. The plugs are cut off and the wires are divided into two parts. The ends of the wire are stripped of insulation. Copper veins need to be twisted, soldered or attached to metal clips. Next, a shallow plastic container is taken and filled with saline or soda solution (1 tbsp per 0.5 l).
Turn on the power supply. The clamps hold on to isolated places at a distance from each other (if they touch, a short circuit will disable the power supply). The clamps must be immersed in a container with a solution. One of them will hiss and release gas - this is a "+".
It needs to be connected to a coin, and the second clip, (respectively "-") is connected to a small metal object (for example, to a spoon or a key).
The second option is reverse connection. The positive clip connects to a metal object, and the negative clip connects to a coin. The reverse connection gently cleans the coin and does not harm its metal core.
Depending on the amount of plaque and the degree of contamination, the cleaning process takes from several minutes (if a “+” is connected to the coin) and 40 minutes to 4 hours(if "-" is connected).
When finished cleaning, turn off the device from the mains, remove the coin from the solution and clean it with a brush with a little liquid soap. To eliminate special, complex contaminants, the procedure will have to be repeated. The solution will become dirty after a while and will need to be replaced in order to re-electrolyze.
Summing up on the topic of cleaning
A method of cleaning coins that would allow them to return to their original appearance exactly, does not exist, but with due diligence, you can significantly improve the condition of the coins. The safest option is to use soapy water.
More severe soiling may require coins to be soaked in solution for extended periods of time. Sometimes you have to wait several weeks for the result.
For prolonged soaking solution needs to be changed. to a new one, and periodically remove the coin itself and clean off the softened layers of dirt from it. For gold coins, this cleaning method is ideal.
After the procedure, the product is dried, wrapped in a soft cloth. Mechanical cleaning is also considered a relatively safe method, but it is absolutely not suitable for soft metals that are easily scratched.
the main task- do not completely ruin the coin and do not deprive it of its noble patina. Some specimens are better not to be cleaned at all, but simply washed. It is recommended that before starting work, practice at the most common coins. Be sure to follow the safety regulations (chemical cleaning methods can be hazardous to health).
Novice collectors and the lucky ones, in whose hands were ancient copper kopecks, rubles, money, fifty dollars, altynniks or hryvnias, looking at them, think: how to clean an old copper coin? And, as it turned out, their most common mistake is an attempt to restore the shine of the coin. And this greatly reduces its market value! Indeed, in the cleaning process, the main thing is not to overdo it and not deprive the coin of a noble patina, emphasizing its antiquity! Let's try to clean the coins at home and not damage our collection.
Things to remember for a newbie
Of course, it is better if your rarities are cleaned by a professional, but it is quite possible to cope with this task yourself. To begin with, the numismatist needs to remember that the natural oxides on an ancient copper coin, which are dark brown and sometimes black, are called patina. You can't delete them! They not only add value to your rarity, but also protect it from destructive action. environment. Consider the patina - if it is even, then simply wash your coin with warm water and wipe it with a soft cloth.
Citric acid will help in cleaning coins
In cases where the oxide layer is uneven and thick, it must be removed. For this, several methods are used. To get started, you should learn how to clean with citric acid, which can be purchased at any supermarket.
- Dissolve three parts of the acid in seven parts of water, thus obtaining a 30% solution.
- Dip a coin into it and wait no more than 15 minutes.
- As a result of a chemical reaction, purification will occur, and the dirt will rise to the surface.
- if the coin acquires a pinkish tint at the same time, it will change in a few weeks.
- After restoration with acid, the coin must be washed in water with soap containing alkali in order to stop the effect of acid on the metal.
Sometimes it is necessary to repeat the cleaning process for better results.
Can laundry soap be used?
Cleaning the collection can be done in another, safer way. Numismatists know very well how to clean copper coins with laundry soap. To do this, it is planed on a fine grater and a solution is prepared (ratio: 1 part of soap and 8 parts of water), stirring it thoroughly. Coins are placed in soapy water for two weeks. Periodically, water is put on fire and heated, not bringing to a boil. Dirt from the coins will begin to come off during this time, however, sometimes (especially if the oxide layer is thick) you have to make additional efforts to clean them (for example, clean them with a soft toothbrush), but most often it is enough to wipe such a coin with a cloth.
By the way, with the help of soap, it is best to restore old and Soviet ones, issued before 1924. And more modern such cleaning can be spoiled!
How to clean copper coins from greenery and other stains
In order to rid the collection material of stains, it can be boiled over low heat in oil. A good result can be obtained using vaseline oil, as it has a rather high boiling point. Namely, it is required for successful cleaning.
Coins are kept in boiling oil for 10 minutes, do not forget to just cover the container with a lid to avoid soot. Then they are allowed to cool and washed with soap. Don't forget to dip the coin in ethyl alcohol for a few minutes to remove the grease. After this procedure, it can take its rightful place in your collection.
How to clean copper coins from oxidation
If the coin is covered with a dark cherry coating of cuprous oxide, then it can be removed by immersing the coin in a 15% ammonia solution (a 10% ammonium carbonate solution is used instead, which is less aggressive towards copper).
Dark green color indicates the presence of copper carbonate. This plaque is removed using (and how exactly, it was described above). A less aggressive way is keeping coins in kefir for 2-3 hours. Do not forget to periodically look at how the purification process is going on.
Sometimes there are also coins that are covered with a pale yellow coating of lead carbonate. This usually indicates that there is a lot of said metal in her alloy or that she has been lying with lead objects for a long time. Such plaque is well removed with a 10% solution of acetic acid.
What to do if rust appears on the coin
If you are worried about how to clean copper coins from rust, you will have to use a slow-acting reagent. This The thicker the layer of rust, the longer the coin will have to lie in the reagent.
And some numismatists advise cleaning with Coca-Cola. This method, although it seems somewhat strange, is nevertheless very effective.
Drying coins after cleaning
After you have succeeded in cleaning copper coins from dirt and oxides, they must be dried. To do this, it is best to use paper towels folded in several layers, and cover your cleaned antique with another towel on top. Use only soft ones for this - so you will not scratch the surface of the coin! By the way, you can completely dry it at a temperature of 100 ° C. And in order to prevent and slow down the oxidation process, periodically rub the collection material with a crumpled newspaper.
What to do if a copper coin has lost its noble patina?
If you still overdid it, or for some reason you had to completely clean the coin, you can restore the patina layer by artificially aging the product. True, cleaned coins themselves acquire a patina over time, but it can look uneven and this greatly spoils the appearance of the collection material. In order to avoid this, the coin is degreased and dipped for 15 seconds in a 10% hyposulfite solution, and after drying it is wiped with a soft cloth. The described operation will help to appear on the antiquity smooth and beautiful patina.
If you still don’t know how to clean copper coins in practice, then you should practice on less valuable items and only then move on to the most expensive items in your collection. In the case when the coin has become unnaturally light as a result of cleaning, put it on a sunny windowsill, where it will take on its normal appearance in a week. True, you must not forget to turn it over regularly.
If you come across a coin affected by the so-called "bronze disease", then it is better to give it to a professional restorer. You can distinguish this by oxides on its surface, similar to light green grains. And the coin itself, as a rule, is badly destroyed and crumbles if you pick it up.
A few last words
We hope that after reading the question of how to clean copper coins at home, it will not seem too difficult for you. But still I would like to warn you that especially expensive and rare specimens of your collection should be given into the hands of a specialist. Otherwise, it may turn out that your rarity is hopelessly ruined.
By the way, paste, salt, baking soda and sand are substances that can cause irreparable damage. appearance collection material. After all, all these are abrasive substances that can scratch the surface of the coin and, accordingly, reduce its value.
Good luck with your restoration and collecting!
Cleaning ancient coins.
(Ed.: "The past of our Motherland in the monuments of numismatics." Leningrad, 1977).
The purpose of this report is to acquaint interested readers with the simplest and safest methods of cleaning coins, which the author can recommend based on his many years of experience in the restoration of archaeological metal in the State Hermitage.
Clearing coins is one of the responsible types of restoration, it is important for their study, dating, identification and storage.
Ancient coins made of silver and copper alloys, found in hoards or other archaeological excavations, most often come to the restoration workshop heavily corroded, and sometimes completely mineralized. Under the influence of water and salts, copper is destroyed in the soil with the formation of green carbonates and chlorides, red copper oxide and black oxide. In corrosion layers bronze coins compounds of tin and lead are found. Silver-copper alloy coins are often coated with copper corrosion products. Sometimes silver under the action of chloride salts turns into gray-violet chloride - horn silver. In air, copper alloys darken from oxidation, and silver - as a result of the formation of sulfide.
The restorer must be very careful about the restoration of numismatic monuments. In particular, you need to do right choice reagent necessary for cleaning from corrosion, since a reagent that is successfully used for some coins may be unsuitable for others, i.e., it will lead to their destruction or to serious distortions of their appearance. It is desirable to achieve and preserve the "noble patina" - a kind of certificate of antiquity of objects.
When starting to clean coins, you should find out: what metal they are made of, whether they have a metal core, to what extent it has been preserved, what salts the coins are covered with.
It is important, for example, to determine the presence of copper chloride in corrosion crusts on copper coins, which in humid atmospheric conditions causes an active corrosion process - "bronze disease".
To detect copper chloride, a humidification chamber of a simple device is used: a glass vessel is filled with water by about 1/3 of the volume; a perforated (perforated) plate made of plastic, plexiglass or porcelain is placed above the water, on which coins with a corrosive layer are placed. The container is tightly closed with a lid. In this state, it is left for 1-3 days.
The action of the humidification chamber is to accelerate the processes occurring under the influence of air humidity, which helps to identify active corrosion centers and makes it possible to choose more successful cleaning methods.
In addition, the presence of coins in the chamber contributes to the loosening of the surface layer of oxides, facilitating further cleaning operations. If there is copper chloride in the corrosion layer, then droplets of liquid, colorless or slightly greenish, will necessarily appear on the surface of the coins. Otherwise, the droplets do not come out: copper carbonate, nitrous oxide and copper oxide are stable in wet conditions (note that horn silver on silver coins is also stable). If copper chloride is found, it must be removed from the deepest pores and very thoroughly.
Often, in archaeological excavations, coins are found “boiled”, i.e., forming a shapeless mass due to the oxides connecting them. We do not recommend separating such coins by heating them and lowering them into cold water. sodium hydroxide solution and heat up to 30-50 °. After that, the coins can be separated from each other, determine the condition of each of them and start cleaning.
The main ways of clearing coins are mechanical, chemical and electrochemical. During restoration, a combination of the mechanical method with others is most often practiced.
Machining consists in removing surface layers: earth, sand and individual corrosion bumps. It is produced using various brushes (bristle, brass and glass fiber), scalpels and dental burs of various sizes. However, these tools must be used with great care. With inept and rough use, they are easy to scratch, which to some extent distort the inscription, images, etc. Chemically, in combination with a mechanical method, coins are cleaned, covered with a thick layer of corrosion products, but retaining a metal base, as well as coins from gold and silver.
To remove a cherry-red coating of cuprous oxide from copper coins, you should lower the coins into a 5-15% ammonia solution, but so that they are completely immersed in the solution, because in contact with air, the effect of ammonia on the metal is destructive. Instead of ammonia, you can successfully use a 5-10% solution of ammonium carbonate, which is less aggressive towards copper and bronze. If copper coins are covered with salts consisting of copper carbonate (dark green), these deposits should be removed with a 5-10% citric acid solution. It slowly dissolves copper salts and oxides and does not dissolve metallic copper.
There are also copper coins covered with a yellowish-pale coating of lead carbonate. This suggests that either there is a lot of lead in the alloy of the coins themselves, or they were lying in the ground with lead objects. To remove such plaque, a 10% solution of acetic acid should be used, which easily dissolves lead carbonate.
Sodium hexametaphosphate (G.M.F.N.) can serve as a “softener” for corrosion deposits on copper coins. It is a vitreous, highly soluble salt. It must be dissolved with continuous stirring, since the vitreous mass sticks to the bottom of the vessel. M.F.N. is used in the form of a 5-20% solution.In a cold state, it acts slowly.To speed up the process, it is necessary to heat the solution to 60-80 °.
G.M.F.N. absolutely safe for metal and due to the slow action allows you to easily follow the progress of cleaning and timely use of mechanical processing.
The restorer often has to deal with coins that are completely mineralized, which are not always possible not only to open, but also to save. The success of the treatment depends to a large extent on which copper compounds have replaced the metal as a result of complex mineralization processes. First, you should carefully, without physical stress, remove surface layers. If in this way it is possible to reveal one or another ornament, inscription, etc., then this should be limited. If mechanical processing has not "opened" the coin, a 5% solution of caustic soda or ammonium carbonate is used.
Taking into account that the degree of preservation of coins submitted for restoration is different, it is difficult to give definite recommendations regarding the time of their residence in one or another reagent. Therefore, periodically removing the coins from the solution, one should gradually remove the softened layers mechanically, thus contributing to the acceleration of the clearing process.
Cleaning of silver coins is carried out mainly in a chemical way. Such cleaning is reduced to the removal from the surface of oxides and salts of other metals, mainly copper compounds. Copper compounds on silver coins are recognized by their green color. To remove them, you need to put the coin in a glass vessel or in a porcelain evaporating cup and pour 5% sulfuric acid solution. To speed up the process, it is possible to carry out cleaning with heated solution, from time to time removing the coin, rinsing with water (preferably running water), then cleaning the mechanically softened salts with brushes - bristle or glass fiber. With repeated operations of this kind, the layers gradually decrease and completely disappear. You can also use a 5-10% solution of formic acid (preferably heated to 50-70 °). It softens well and removes oxides and carbonic compounds of copper on silver. The hotter the solution, the stronger its effect. The formations of violet-gray horn silver are exceptionally soft. Such coins often lack a metal core, and the possibility of their complete loss cannot be ruled out during cleaning. But if the crust of horn silver is not too thick, the coin can be immersed in a 5-10% solution of ammonia or ammonium chloride. In these solutions, horn silver softens, after which it is carefully removed mechanically.
For coins that have retained a metal core, but have very dense, hard, "thick" oxides, as well as fragile coins, the electrochemical reduction method can be applied. This method does not require special equipment. Zinc and aluminum are usually used for electrochemical processes. Practice has shown that for cleaning coins, it is best to use plates made of sheet zinc or aluminum, with holes punched in them (like a grater).Caustic soda or formic acid of 5-10% concentration is taken as an electrolyte.At the bottom of a glass vessel (it is clearly visible recovery process), the aforementioned zinc or aluminum plate is placed. Several coins are laid out one to the other on the “worn” surface of the plate, which are covered with the “worn” surface of another similar plate. After that, the vessel is filled with the prepared solution so that the coins with the plates are completely hidden.
Processing in this way should be carried out with particular care and caution, with frequent monitoring of the progress of the process. Mechanically removing the restored and softened corrosion products, they examine the coin through a magnifying glass to determine the degree of its clearing. After inspection, if necessary for a clearer identification of the image, it is again subjected to electrochemical processing.
Note that gold and "new" coins that have not been in the ground, but have only been in circulation for a long time, are cleaned easily and quickly. Fatty substances must be removed from them with acetone, gasoline or alcohol and lowered into a 5-10% sulfuric solution. , citric or formic acid.
After cleaning the coins in one way or another, they should be thoroughly washed (“digested”) in several changes of boiling distilled water until the water is neutral according to the universal indicator and soluble chlorides are completely removed: the cooled sample of the last wash water should not become cloudy from the introduction of a drop of 1.7 % solution of silver nitrate.
After washing, the coins are dried in acetone, then in alcohol for 30-60 minutes. For this purpose, you can also use a thermostat (special drying cabinet), keeping coins in it for no more than two hours at a temperature not exceeding 100 ° C.
Copper coins that showed signs of bronze disease are again placed in the humidification chamber after cleaning. If drops of copper chloride appear in some places, these pockets are carefully cleaned mechanically, and the coins are “boiled” again.
If copper coins have an unpleasant sheen after cleaning, a light to dark brown patina can be artificially created. To do this, you need to take 50 g of copper sulfate and 5 g of potassium permanganate per liter of distilled water. In the prepared solution, heated to 70-80 °, lower the coins and hold until the desired shade is obtained.
After drying, the coins must be preserved with a protective coating - paraffin or synthetic resins. For this, 5% solutions of polybutyl methacrylate in acetone, toluene or xylene and polyvinyl butyral in alcohol or a mixture of alcohol and benzene (1: 1) can be recommended.
After conservation, it is necessary to store the coins not in “heaps”, but in separate boxes or trays with compartments. In this form, they will not touch and better retain their protective coating. In addition, when examining restored coins, it will be easier to identify those on which corrosion has reappeared.
additional information about the restoration of metal can be found in the books of M.V. Farmakovsky "Conservation and restoration of museum collections" (M., 1947) and X.D. 10-11).
Coin cleaning, option 2.
Coin cleaning is the process of removing a layer of dirt and more or less significant traces of oxidation from the surface of a coin. The easiest way to remove dirt. It can be removed by washing in warm soapy water or using a soft brush. Moreover, this method is suitable for absolutely all monetary metals.
It is more difficult with oxidation. Because in this case it is necessary to take into account the nature of the monetary metal. If it is gold, then washing in warm soapy water is sufficient. If it is silver, then it is desirable to know the sample of the coin alloy.
Silver not lower than the 625th test is cleaned with a special tool - a silvertauschbader. An effective remedy is also a solution of ammonia, as well as an acidic fixer used by amateur photographers.
Base silver can be cleaned by immersing it in lemon juice for several hours. But in all cases with the cleaning of silver, the simplest and most affordable means is to wipe the coin with a slurry of moistened sodium bicarbonate, in other words, baking soda.
Silver coins are immersed in the solution in such a way that they do not lie tightly on the bottom or on top of each other. They need to be turned over from time to time. After complete removal of plaque, the coins should be wiped with a soft cloth.
All copper coins are washed in warm soapy water. by the most in a simple way cleaning copper coins is to immerse them in a 5-10% solution of acetic acid. Simple table vinegar will do the same. Depending on the condition, size and type of plaque, coins should be in solution from several minutes to several hours or even longer. They also need to be stacked, turned over and wiped, as is the case with silver coins.
To apply this cleaning method, you must first figure out what kind of oxide layer is on the coin. The most detrimental thing for a coin is the so-called. "copper" (green copper). This is a poisonous oxide layer based on copper acetate, which appears under the influence of acetic acid vapor, which interacts with atmospheric oxygen.
The formation of verdigris is also possible on silver coins with a significant copper content. In this case, the so-called. "flowers" that are difficult to remove. In general, it is better to entrust the cleaning of copper coins to a specialist.
A completely different matter is patina, a layer of oxides formed on the surface of a metal under the influence of oxygen, carbon, acids and salts. It does not spoil the coin, but rather preserves it. Patina is considered beautiful and valuable, and its presence is often a sign of authenticity. The patina, as it were, preserves the coin, so it is not recommended to remove it.
Iron and zinc coins require a particularly careful approach. To clean these coins, it is recommended to wash them in dilute hydrochloric acid, followed by cleaning them with a brass wire brush.
With these types of coins, it is recommended to very carefully, with the tip of a knife or scalpel, remove rust and whitish deposits. At the next stage of cleaning these coins, vigorous rubbing against a piece of cloth or felt, dense fabric helps well. If you resort to treatment with a solution of hydrochloric acid, then you need to be very careful with the degree of its concentration, because. if the concentration is excessive, the drawing on the coin can simply "burn out". After treating the coins with a salt solution, they should be washed in warm soapy water and wiped dry with a soft cloth.
Lead, tin or aluminum coinage is not recommended to be cleaned with chemicals. Slight traces of dirt can be removed with a so-called glass brush. Friction on felt or cloth helps well. After cleaning coins of any metal, copious rinsing in warm and cold water is necessary to prevent re-damage to the surface.
Electrolysis.
Warning: While electrolysis is a popular form 
cleaning ancient metal objects, especially coins, there is a certain danger inherent in the use of any electrical device. The creation and use of such a device should be carried out in a well-lit and ventilated area using safety equipment such as goggles and rubber gloves. Even if the risk of death from electric shock is extremely low, you should never relax while using any electrical device.
Electrolysis is a quick way to clean coins. What takes months with olive oil can be done in minutes (and even seconds!) with electrolysis. Of course, this increases the risk of destroying your coin. Even with great care, you can get an unsatisfactory result, although initially a dirty coin showed great promise. Since electrolysis strips the patina of the coin, you are playing gambling, the result of which depends on how good the core of the coin is. Sometimes it happens that the coin consists entirely of one patina.
The first thing you need is an old 6 to 12 volt power supply. Higher voltage increases the risk of electrocution with little improvement in cleaning efficiency. Cut off the plug on the end of the power supply wire. Divide the end of the wire into two parts and strip the ends of the insulation. Twist the copper strands and, if possible, connect them to metal clamps. For example, for $3 you can buy a dozen of Radio Shack's copper-plated micro alligator clips.
Put it all aside and take a not very deep plastic bowl. Fill it with water to the depth necessary to clean the coin you have chosen, and dissolve the table salt in it. You shouldn't take a lot of salt, just a couple of spoons or so.
Connect the power supply to the mains, keeping the two clamps away from each other. If they touch, a short circuit will occur and the power supply will fail. Dip the clamps into the solution and notice which will release gas and hiss. You must connect this clip to the coin. Connect the other clip to a metal object. It can be something small, like a key or a spoon. Don't use copper or brass for this, as they don't work very well. You now have an electrolysis kit.
Dip both clips into the solution and your coin should begin to sizzle and bubble. Depending on how thick the layer of dirt and oxides is on your coin, the cleaning process should last from half a minute to several minutes. The coin should bubble vigorously. If the gas release is small, then this is also not bad, just the process will go more slowly. The rate of electrolysis can be increased by adding more salt to the solution, or by bringing the clamps closer together without actually touching them.
Remove the coin from the solution and clean it with a toothbrush with a drop of liquid soap. If you've kept the coin in the solution long enough, the dirt should start to fall off, but you may need to repeat the electrolysis process again. Very stubborn impurities may not succumb to electrolysis at all and must then be removed with a knife or other mechanical tool.
After a while, you will notice that the solution in the bowl will become dirty. This does not come primarily from the coin, but rather from the metal anode that dissolves into the solution. You should replace the solution as often as the anode as it wears out.
The easiest and safest way to clean coins.
Clearing coins is one of the most important types of restoration, to study their dating, determine the country in which they were minted and their subsequent storage.
Ancient coins made of silver and copper alloys, found in hoards or during archaeological excavations, most often arrive at the restoration workshop heavily corroded, and sometimes completely mineralized.
Under the influence of water and salts, copper is destroyed in the soil with the formation of green carbonates and chlorides, red copper oxide and black oxide. Compounds of tin and lead are found in the corrosion layers on bronze coins.
Silver-copper alloy coins are often coated with copper corrosion products. Sometimes silver under the action of chloride salts turns into gray-violet chloride - horn silver. In air, copper alloys darken from oxidation, and silver - as a result of the formation of sulfide.
The most common problem is copper cleaning. Under the influence of a humid atmosphere, salt and sulfate compounds in the air, as well as in the ground, copper is destroyed with the formation of chlorides, green carbonates, black oxide and red oxide of copper, copper alloys darken from oxidation by atmospheric oxygen.
It is necessary to be very careful when cleaning and restoring numismatic monuments. First of all, a properly selected chemical reagent necessary for removing corrosion will give you a guarantee for the entire further restoration process. However, a well-chosen reagent in some cases may be completely unsuitable for other things and may lead to their destruction or serious distortion of their appearance.
The second task is to identify what metal the found coins are made of, and to what extent the corrosion process has affected the metal itself, that is, how deep the decay process has gone.
Preliminary preparation for restoration requires the involvement of the work of chemical and physical laboratories to clarify the first two tasks, which, of course, is not always possible. Here are the most simple tips available to almost everyone in our time.
Often in archaeological excavations, coins are found "boiled", that is, they form a shapeless mass due to the oxides connecting them. We do not recommend disconnecting such coins by heating them and lowering them into cold water. In order to avoid losses, such a "lump" should be placed in a 5-10% sodium hydroxide solution and heated to 30-50 °. After that, the coins can be separated from each other, determine the condition of each of them and start cleaning.
The main ways of clearing coins are: mechanical, chemical and electrochemical. During restoration, a combination of the mechanical method with others is most often practiced.
Machining is done using various brushes (bristle, brass or glass fiber), ordinary needles (sewing and medical), scalpels and dental instruments. They must be used with extraordinary care and great manual dexterity. With inept and rough use of this method, you can easily cause scratches that distort inscriptions, images, etc., or you can simply break the thing.
Copper coins must go through a chemical process before being machined. For this, it is best to use a 5% sodium hydroxide solution or a 5-10% ammonium carbonate solution, which dissolve and soften copper salts and oxides and do not damage metallic copper. To do this, the coins are completely immersed in the solution and kept in it for at least 24-48 hours. Then the coins must be washed and mechanically processed, preferably with a brass brush. Depending on the extent to which it was possible to remove the corrosion products, this process can be done again.
Taking into account that the degree of preservation of coins is different, it is difficult to give definite recommendations regarding the time of their residence in a particular reagent. Therefore, periodically removing the coins from the solution, it is necessary to gradually remove the softened layers mechanically. After we see that the surface of the coin has got rid of the cherry-red coating of cuprous oxide, the yellowish-pale coating of lead carbonate or the bright green of copper chloride, we must proceed to the next stage, the so-called "digestion". Coins must be thoroughly rinsed in several changes of boiling (preferably distilled) water until the water is neutral. In most cases it is better to boil them in several waters.
After washing, it is necessary to dry the coins by placing them in acetone, and then in alcohol for at least 30-60 minutes. You can also use a special cabinet (thermostat) for this purpose, keeping coins in it for no more than two hours, at a temperature not exceeding 100 ° C. I would especially like to pay attention to copper coins that had the green of copper chloride. After cleaning, they must be placed in a humidification chamber. If points of copper chloride appear in some places, these centers are carefully cleaned mechanically (with needles, dental instruments) and the coins are "boiled" again.
After the final drying on the coins, it is better to create a protective layer. To do this, the coins are covered either with a special varnish, or with paraffin or synthetic resins. Cleaning of silver coins is carried out mainly in a chemical way. To remove silver oxides, it is best to use a 5-10% solution of formic acid, which softens well and removes not only oxides, but also copper carbonates on silver. Silver coins are placed in a solution of formic acid, in glassware, and the process of cleaning them will take place before our eyes. To speed up the process, it is possible to carry out cleaning with heated solution, from time to time, removing the coin, rinsing it with running water, then cleaning the mechanically softened salts with brushes - bristle or fiberglass. After cleaning silver coins, a washing and drying method similar to the method with copper coins should be applied.
The simplest cleaning method is applied to gold and platinum coins, which is mainly preventive cleaning, i.e. to remove fatty substances and dirt that have formed as a result of a long stay in the ground. Fatty substances are removed with the help of medical cotton wool, 
moistened with acetone or alcohol.
After drying, the coins must be preserved, covered with a protective layer - paraffin or synthetic resins. To do this, we can recommend 5% solutions of polybutyl methacrylate in acetone, toluene or xylene and polyvinyl butyral in alcohol or a mixture of alcohol and benzene in a ratio of 1:1.
After conservation, it is necessary to store coins in separate boxes or trays with compartments. In this form, they will not touch and better retain the protective coating. In addition, when examining restored coins, it will be easier to identify those on which centers of corrosion have reappeared.
If for the first time you have in your hands old coin, and you are wondering how to clean it, then this article can help you. After all, it often happens that out of inexperience, novice collectors spoil coins, trying to clean them to a shine, thereby sharply reducing their market value.
The main thing is not to overdo it!
A coin that does not contain dirt and oxides that form on the metal as a result of its corrosion does not need to be cleaned.
If the coin was found in the ground and there is a layer of dirt or clay on it, then such a coin should be washed with lukewarm water and soap, if the dirt is hard enough, you can use a soft-bristled toothbrush for cleaning.
In this way, ordinary dirt is removed from coins from any alloys.
If there are oxides, then for further proper cleaning, you need to try to determine what alloy the coin is made of.
On gold and silver coins of high standard, oxides are practically not formed. Such coins are only washed in the above way, and trying not to rub anything in particular, so as not to scratch. After washing, the coin must be dried with a soft, lint-free cloth and can be put away in the collection.
Low-carat silver coins are easiest to clean with a 9% solution of table vinegar, or use a weak solution of citric acid. The time it takes to clean the coin depends on its size, and on the amount of oxides. Usually, it is enough to leave the coin in the solution for 3-5 hours so that it cleans up well enough.
After treatment with an acidic solution, the coin must be washed with running water and soap containing alkali to stop the effect of acid on the metal.
Advice.
If you accidentally overdo it with the cleaning of the coin and it has acquired an unnaturally light shade. Leave the coin on the windowsill, on the sunny side. After a week, a beautiful uniform patina forms on the coin, the main thing is not to forget to turn it over regularly.
Cleaning copper coins
The most common and most difficult to clean are copper coins, especially if they have lain in the ground for several years. If there are no noticeable green spots on the coin, then it just needs to be washed and dried. Natural dark brown oxides, sometimes even almost black, are called patina - they cannot be removed. They represent the natural defense of the coin. The more even the color of the patina, the more beautiful the coin.
If there are dark green spots on the coin, then the coin should be cleaned with a 9% solution of table vinegar or citric acid. The cleaning time also depends on the degree of damage to the coin by oxides. After cleaning, rinse and dry the coin.
Sometimes there are coins affected by the "bronze disease". They cannot be cleaned at home, without special chemicals. Determining this disease in a coin is quite simple. Oxides are light green grains, the coin is badly destroyed, literally crumbles in the hands. If you come across such a coin, do not try to clean it yourself. If the coin is very rare, you need to contact a professional restorer.
