Cleaning coins in oil. Is lemon juice good for cleaning coins? Boiling coins in soda solution

Novice numismatists and treasure hunters are often faced with such a question as cleaning copper coins. Can this be done at home? You can clean old or old coins with ammonia, vinegar or mechanically. Important to choose the right recipe so as not to damage the surface and not spoil a valuable copy.

Dirt and stains are a small part of the damage. More often, plaque forms on the surface. It is caused by chemical reactions that occur as a result of the interaction of money with gas exchange under conditions environment. There are several types of plaque:

Green plaque is copper carbonate dihydroxide.
Blue plaque - copper azurite.
Black plaque is copper sulfide and oxide.
Red with a brown tint plaque - copper oxide.

If we are talking about old and very expensive coins, then take extra care. Do not use aggressive means, there is a risk of irreversible damage. For light soiling, use the following methods.

Soap solution for coins (excerpt)

Allows you to clean the most persistent dirt on the surface of metal money, but it has advantages and disadvantages. I must say that the method is the most sparing, it allows not only to preserve the features, but also to return the coin to its original form, unless, of course, it was mechanically damaged.

With a soapy solution, start any cleaning at home. Soaking in a slurry made from soap is a more effective cleaning method. You will need:

Laundry soap.
Water 100–150 ml.

Grate soap on a coarse grater, pour in water and mix the composition. After a while, when the soap swells, immerse the coins in the resulting slurry. If necessary, add water to the mixture, the consistency should be slightly thicker than sour cream.

After 2 days, take them out of the gruel, scrub gently with a soft-bristled toothbrush, and dip them back into the soap mixture. Please note that the prepared composition dries out over time, add water so that the mixture does not lose its consistency. The duration of exposure depends on the degree of contamination. Sometimes it takes up to 1.5 months, which is the obvious disadvantage of this method. But the result is excellent, and the money will not be damaged.

The method will help to put in order even royal coins, the integrity of which is especially important to maintain.

Cleaning coins with soda (cooking)

Take the following ingredients:

Vinegar essence 1 part.
Water 10 parts.

Mix the components and immerse the coin in the resulting composition, the solution should completely cover it from above. You can soak several pieces at once. Every 12 hours they must be taken out and the oxides removed with a toothbrush. It takes from 3 to 10 such procedures, depending on the degree of oxidation. The cleaning ends with drying - first it must be wiped with alcohol, and then put for several days in a warm place, and only then in an album with a collection of tsarist and Soviet times coins.

Vinegar-salt way to clean coins

Coins of the USSR from a copper-nickel alloy can be cleaned with an acetic-salt solution. This method consists of several stages:

Take a small container, pour 100 ml of vinegar into it and add 1 tbsp. a spoonful of salt. Stir.
Immerse the money previously washed with soap into the solution so that they are completely covered.
Then you can see the chemical reaction - the surface will begin to turn white, and its contents will become more clearly visible.
After 10-15 minutes, the coin can be removed with tweezers, then clean it gently with an eraser. If necessary, repeat the entire procedure from the beginning.

In no case do not heat the acetic-salt solution, otherwise the coins will be completely damaged.

After cleaning with vinegar, the patina may be damaged, cavities and other uneven parts may open, you should be especially careful.

mechanical cleaning

The mechanical method is the best and preferred by most numismatists. It is carried out using a special instrument under a microscope. It is carried out by experienced restorers, since it is important not to harm, but to help the coins recover. If you have a valuable old coin in your possession, do not try to clean it yourself. Choose the method of mechanical cleaning by passing it on to specialists.

Cleaning copper coins is a rather laborious process that requires concentration, compliance with proportions in the preparation of solutions and exposure times. But as a result, you will save your finds and be able to replenish your collection with new items.

Not really

Interest in numismatics in our days shows everything more people. The hunt for rare coins is gaining momentum. Unfortunately, almost any metal is susceptible to oxidation, which negatively affects the appearance of the product. Cleaning coins is the only way to deal with this problem. The tips in this article will help you do it quickly and efficiently.

Exists big number techniques that can be used to remove contaminants. Cleaning coins at home is a task that anyone can handle. Be sure to follow the recommendations below.

The cleaning technique must be chosen depending on which alloy the affected specimen is made of. Otherwise, there is a danger of irretrievably ruining the coin, rather than saving it.
It is advisable to refuse products containing abrasive particles. There is a high probability that their use will lead to scratches on the surface of the coin.
Cleaning coins with concentrated acids is also not welcome. First of all, this applies to specimens made of copper.
Removing the patina can lead to a decrease in the value of the coin. For some products, it serves as a decoration.
It is advisable to check the selected remedy before the procedure. Experiments can be carried out on products that are made of a similar material.

Silver

How to restore the original beauty of silver coins? Cleaning with a solution of ammonia and baking soda- an excellent choice.

In glass hot water it is necessary to dissolve two tablespoons of soda. You can also add a few drops of dishwashing detergent. The product is placed in the resulting mixture for approximately eight hours. Then the coin is thoroughly washed and dried.
In a glass of hot water, add 30 ml of hydrogen peroxide and a teaspoon of ammonia. The affected specimen in this solution must be kept for about 15 minutes. The mixture is then diluted and drained until the silver is in clear water. Next, the coin is thoroughly washed, wiped with a soft cloth.

If the choice is made in favor of the second method, maximum caution must be exercised. The coin must be turned over without removing it from the liquid. There is a possibility that an oxidation process will occur in air. In this case, the metal will be damaged.

Copper

How is copper coins cleaned at home? These products are famous for their capriciousness, so it is necessary to return them to their original beauty with care.

Vaseline oil. The affected specimen must be boiled in it until the pollution disappears. The final part of the work is washing the coin in alcohol and drying it with a soft cloth.
Hydrogen peroxide. This tool will help restore the lost shine to the product. Dissolve 30 ml of peroxide in 200 ml of water, and then add a teaspoon of ammonia. The coin should be kept in such a mixture for no more than 15 minutes.
Soap with a neutral environment (household, children's). It must be grated on a coarse grater. The resulting porridge should be coated with a damaged copy on both sides. In this form, the product will have to be left for a long time, which is the main drawback of this gentle method of cleaning copper coins. From time to time it is necessary to remove the specimen and clean it under running water with a soft brush. This will remove softened contaminants. The procedure continues until the desired result is achieved.

Bimetallic

When creating some coins, for example, anniversary copies, two different metals are used. The central part is made of silver or steel, and gold, copper or various alloys are used for edging. How to clean such a product?

Dishwashing liquid. You can use, for example, "Fairy". Dissolve one tablespoon of the product in a liter of water, mix thoroughly. The coins are kept in the liquid for about an hour, then removed and wiped with a flannel cloth. Dishwashing liquid shows excellent results when fighting minor dirt.
Toothpaste. It is necessary to apply a pea of ordinary paste on a brush with soft bristles. Rub the affected specimen carefully, strong pressure is not required. Cleaning of coins ends with rinsing in water.
Paste GOI. This tool includes fine abrasive particles, which allows it to effectively deal with dirt and oxides. It is worth using paste exclusively for inexpensive coins, since there is still a risk of damaging the product.
Formic acid. This product will help restore the original shine to the specimen. It is necessary to lower the coin that needs cleaning into a 14% solution for about five minutes, and then polish it. Instead of formic acid, alcohol is allowed.

cupronickel

Cupronickel is also able to oxidize and blacken, has a composition similar to noble metals. For cleaning coins at home, the methods discussed below are suitable.

Ash. With it, you can quickly and effectively rid the product of patina. The affected specimen is dipped in water, then cigarette ash is applied to it. Approximately 20 minutes later, the coin must be rinsed.
Dish powder. This tool is applied to the product after wetting it with water. It is necessary to treat the surface of the damaged specimen with a sponge and wait for some time. Then the coin is washed in water.

brass

How to choose a cleaner for coins made from copper-zinc alloy? Such money is not particularly susceptible to corrosion, but periodically still needs to be cleaned.

Oxalic acid. This product can be purchased at the store. With its help, it is easy to remove plaque, it shows good results even in the fight against chronic pollution. Coins should be immersed in acid for about ten minutes. Be sure to thoroughly rinse the money with water after the cleaning procedure.
Trilon-B. This product must be dissolved in pure water, observing the proportion of 1 to 10. Then the coin is lowered into the resulting solution. She shouldn't be in it all the time. From time to time, the specimen must be washed in running water and inspected. Soaking is repeated until the desired result is achieved.
Other means. What other ways to clean coins from exist? Citric acid, Coca-Cola, thick soap solution.

Aluminum bronze

What tools to give preference in this case? Copies of this material can be cleaned in the same ways that are suitable for copper coins. There are others effective methods.

Coca Cola. This popular drink is not only drinkable, it has also gained a reputation as a good stain remover. Main disadvantage This method consists in a long wait for the result. Coins will have to be kept in a glass of Coca-Cola for about a week. Then they need to be washed clean water.
Sanitary cleaner. The affected specimen must be lowered into such a solution for no more than a couple of minutes. Then it is cleaned with running water.

Commemorative coins of the USSR

There are instances that need special care. For example, how to return the lost attractiveness to commemorative coins of the USSR at home? Cleaning in this case is done using an ordinary eraser. This must be done carefully so as not to damage the pattern.

With an elastic band, rub a dry surface until the plaque disappears. This method is suitable for giving shine to any alloy products.

Universal remedy

What methods are suitable for bringing any coins back to normal? Exists universal remedy which contains several ingredients. It will help to cope with rust, green plaque and other oxides.

It is necessary to mix 25 ml of soda and soap solution. 25 ml of ammonia, 75 ml of toothpaste are added to the resulting mixture.
In the finished product, it is necessary to immerse all specimens that need to be cleaned. There they remain until the goal is reached. Periodically, coins should be removed, rubbed with a toothbrush and inspected. At the end of the procedure, they are washed with water.

by electrolysis

Working with electrical appliances implies knowledge of safety precautions. Also, we must not forget that their use significantly increases the likelihood of damage to copies. Cleaning of coins by electrolysis is carried out in a well-ventilated and illuminated room. Be sure to take care of the protection of hands and eyes.

It is necessary to prepare a power supply with a voltage of 6-12 V. Next, the plugs are cut off, the wires are cut into two parts. Then you should clean the ends and attach the copper wires to the clamps.
The plastic container is filled with brine. It is easy to prepare it by dropping a tablespoon of salt into a liter of water.
The power supply is connected to the network, the clamps are lowered into the resulting solution. The “+” clip should be connected to the coin, on which hissing will be heard. The whole procedure will take no more than ten minutes.

Vinegar

What other ways can be applied? Vinegar is a remedy that is suitable for bringing inexpensive specimens into proper shape. It must be remembered that the solution can corrode the surface of the product, change its color. In addition, it is believed that after such a procedure, the coin will deteriorate faster.

An instance that needs cleaning can be dipped in a solution of 10% vinegar for a day. This is the easiest way.
You can also make a mixture of vinegar and salt. Approximately 5 g of salt must be mixed with a quarter tablespoon of vinegar. You need to stir the mixture until the salt dissolves. Then coins are lowered into the resulting solution. This must be done so that the instances lie separately from each other. Products are soaked in the solution for no more than five minutes. If the dirt remains, you can additionally brush them. Next, the specimens should be gently rinsed in running water.

Cleaning coins with vinegar is a dangerous choice. Its use can adversely affect the appearance and condition of products made of silver, copper, aluminum, lead.

Mechanical restoration

What other options are available? Mechanical cleaning of coins is used to remove surface deposits. We can talk about sand, earth, individual tubercles of corrosion. For the procedure, various brushes are needed (brass, bristle, glass fiber). You will also need dental burs. different sizes, scalpels. These devices must be used with the utmost care. With inept use, there is a danger of scratches that distort images, inscriptions, and so on.

A damaged copy must be kept for about an hour in distilled water. This is necessary in order to desalt the product, get rid of dried dirt.
This is followed by impregnation of the coin with synthetic resin. This is required to strengthen the noble patina, to prevent damage.
Then you can proceed directly to cleaning the tools. This work is very painstaking and lengthy, it will require a huge supply of patience. Some copies of the master can be cleaned within a month or two.

Mechanical cleaning is a method that is more suitable for professionals. Amateurs run the risk of hopelessly spoiling the coin. Therefore, it is recommended to develop appropriate skills on specimens that are not of particular value.

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If you are interested in searching for old coins, then you must have come across the fact that the coins found are sometimes simply impossible to identify, and in order to find out at least the denomination of a coin, it needs to be cleaned. Well, this is the worst case. Often coins need to be cleaned, because they have a green coating, various salts and just a centuries-old layer of dirt. So I decided to summarize all the ways to clean coins. In this article, we will explore all the ways copper coin cleaning. So how do you clean copper coins?

Firstly, I will immediately warn you, if the coin is quite rare, then you absolutely should not clean it yourself. For me personally, a rare coin is worth more than 3,000 rubles. Agree, it will be very disappointing if you ruin such a coin by using not The right way cleaning. So if the coin is rare, it’s better not to clean it yourself, but to sell it right. Whoever buys it will clean it himself or give it to restorers for cleaning. Also look carefully at the patina - if the patina is even, then you should not clean such a coin with anything, just rinse it in warm water and wipe it with a soft cloth. The patina reliably protects the coin from corrosion.

Cleaning copper coins with ammonia.
I myself very often use ammonia, but only very carefully. It must be remembered that ammonia changes the color of copper and when exposed to ammonia, the coin can become absolutely red, which, you see, is not very beautiful. So you need to clean with ammonia carefully, if you lower the coins completely into the ammonia, then not for long and constantly monitor the process. And it is even better to lower the coin for 5-10 seconds, then take it out and wipe it with a soft cloth.

Ammonia, as well as Trilon B, changes the color of the coin. But the color of the coin can be restored if the coin is artificially aged or, as they say, apply patina to a coin. Although brushed coins will develop a patina on their own, it can be uneven and not always natural. So if this happened, then you can try to patinate the copper coin yourself. This is done like this - after cleaning the coin, degrease it and lower it from 10 percentage solution hyposulfite for 15 seconds. When the coin is dry, wipe it with a soft cloth. The patina will be smooth and beautiful.

Well, you came back from the cop and you have a couple of copper coins in your possession that need to be cleaned. The most important thing when cleaning is to choose the right way, but this is sometimes oh so not easy. So first carefully study the coin with a magnifying glass. If there are oxides on it and it is difficult to see letters and numbers, then first we place such a coin in a vessel with distilled water. We take one and a half, cut off the top, put some kind of stand for the coin inside, it is desirable that it be with holes. We put the coin on a stand and fill it with distilled water. It is also desirable to close the top. We leave for 2-3 days. Distilled water softens all corrosion, so after soaking in water, we proceed to the mechanical cleaning of the coin. For this we need toothpicks. We carefully peel off the growths on the coin, we do everything very carefully. So we pick with a toothpick, periodically wash off what we have chopped off. The first stage of cleaning copper coins has been completed, most of the oxides have been cleaned.

Next, you can dip the coin in soap, the most popular way to clean copper coins is with soap. For this we take the usual laundry soap, rub it on a coarse grater into some shallow container. Then pour all the flakes with warm water until a thick slurry is formed.
then we lower our coins into this mass and leave it for a long time. About once a week we take out the coins and clean them with a soft toothbrush. As soon as a green mass appears in the container, it's time to work with a toothbrush. Cleaning copper coins with soap sometimes gives amazing results. As a rule, most copper coins are cleaned with soap, this is the most humane way. If you came from a detective, then you can immediately soak all the coins in soap and periodically brush them with a toothbrush, removing green plaque, dirt and even oxides. After all, soap is a weak alkali, it has an excellent effect on oxides. So if you don’t know how to clean coins yourself - just soak them in soap, it won’t be worse for sure. But this method is only suitable for old copper royal coins. If you try to clean the tips like this, the result may not please you. So he ruined a lot of Soviet coins. So soap is for old royal coins. well, if advice, then until 1924, they are heavy copper, they are also perfectly cleaned. By the way, in order for the soap to react faster, you can heat the soap solution, the reaction will noticeably accelerate.

It is also worth noting such a method of cleaning copper coins as boiling in vaseline oil. You can buy this oil at any pharmacy. Next, pour the oil into an iron container, lower the copper coins there and put it on a slow fire. Be sure to close the lid, otherwise the soot will be such that mom does not grieve. When the oil boils, wait 10 minutes and then remove from heat. Be sure to let the oil cool, remove the coins and clean with a soft toothbrush in soapy water. As a rule, all soot and blackness are erased with a brush, as a result, the coin becomes even and beautiful. But here, of course, sometimes it turns out differently. Once we ruined a few coins like this, because they had only patina, the core of the coin simply did not exist. And she just cooked with us like porridge. So before cooking, carefully inspect the coin. But as a way to clean copper coins, cooking in oil has a place to be. Try, experiment. Only on unnecessary killed coins))

Cleaning copper coins with citric acid.
Some use citric acid. But this is already an aggressive method and requires constant monitoring. You need to be very careful cleaning with citric acid, it can instantly eat the entire pattern and relief of the coin if you overexpose the coin. So I don’t use lemongrass, but people use it and the results are good.

Also excellent for cleaning copper coins drug Trilon B. But here you need to be careful and correctly determine the thickness of the oxide layer. The thicker the layer of oxides, the longer the exposure time to Trilon. If you clean copper coins correctly, then the coins can improve amazingly. But it is also worth bearing in mind that when cleaning with a trilon, all shells and small cracks can open on a coin. So if the coins are on appearance looks good - then the trilon will help to further improve the appearance of the coin.

Cleaning copper coins with kefir.
Another great way, which is excellent for freshly unearthed coins. Efficiency on a par with soap. Kefir is an acid, very weak, so you should not be afraid that the coin will deteriorate. We take kefir and fill the copper coin completely. Now sometimes you look - once every half an hour, what is there and how. As a rule, greens immediately begin to appear in kefir, oxides dissolve. The method is great for copper coins. Usually 2-3 hours are enough to completely dissolve the green oxides on the coin.

Well, another good way to clean copper coins is olive oil. But I will immediately warn you that this method is the longest, but also the safest. Just take the copper coins that. you need to clean and put it in olive oil for a couple of months. After 2 months, you take it out, work a little with a soft toothbrush and back. So clean about 4-5 months. Coins are obtained as if from a treasure, in collectible preservation. So if you have nowhere to hurry - dip in olive oil for half a year))

After cleaning, copper coins can be rubbed with wax or oil. This is how they become marketable, so you can sell them perfectly at auctions.

Any novice treasure hunter is interested in the topic of cleaning found items, including coins. First you need to understand that the main cleaning methods that will be effective in your case depend on the alloy of the sample you found.

Silver, nickel, copper gold and coins of other alloys are cleaned differently. In this article, you will learn how to clean copper coins. According to statistics, finds made of this metal are the most frequent and, after discovery, they definitely need to be cleaned. Professionals will help to clean the find correctly, since this matter is quite delicate and the process itself can be quite complicated, it is especially difficult to preserve the patina layer or if you have one of the representatives of royal coins. But not every treasure hunter is ready to pay the cost of the procedure or put the found coin at risk, which is why we have presented you with the most effective options for self-cleaning copper coins at home. You will find various ways from frankly simple cleaning with soap to semi-professional trilon.

coin preservation

The first thing a novice treasure hunter needs to know is that it’s not enough just to throw your copper find into a bag and start processing after a while. It is very important not to damage the patina, the patina layer is a plaque formed during the years of burial underground, which can protect the product from severe damage and retain its original value.

It is worth taking on a find with plastic tweezers, and storing it in a non-metallic container, preferably also plastic. You can avoid the impact of a coin with external irritants with the help of conservation. There are two most popular types of preservation:

1) Filling the container with cotton. A temporary measure, sufficient for transportation, but not for long-term storage.

2) Filling the container olive oil. Ideal for both transportation and long term storage.

Cleaning copper coins

Everyone who has ever encountered self-cleaning copper medallions will say that spoiling such a product is as easy as shelling pears.

Strong mechanical, chemical or acidic action will inevitably damage the patina and in the case when the specimen is very rare, it is worth considering the help of professionals.

For everyone else, there are several options that can be most safely cleaned.

1 way: soap solution

Soap is the most sparing option, the essence of such a process is very simple. We choose soap without unnecessary impurities (best of all household), three it on a fine grater. Dilute to a homogeneous thick mass with boiling water and place all copper finds in a non-metallic container, preferably plastic. From time to time it is worth removing the coins from the soap and rinsing under running water using the softest toothbrush.

Such a tool has its drawbacks:

- overdoing it with the brush can cause damage to the coin;

– the whole process can last from 1-2 weeks to several months.

2 way: citric acid

Various oxides of low concentration will help to clean the product in a short time, citric acid, which is present in almost any kitchen, is ideal for these purposes. Acid crystals must be diluted until completely dissolved in a non-metallic container and a copper coin placed in the solution. The cleaning process will begin instantly, but along with this, all unpleasant chips, scuffs and other minor damage will appear.

3 way: oil cooking

Cleaning coins in this way is suitable for those who are not afraid of getting burned, because the whole point of cleaning is that the coins are placed in a pan with oil (olive or sunflower), and then they begin to boil. The danger lies in the fact that one by one the coins should be removed from the container and given a slight mechanical effect with a soft toothbrush. If you do not overdo it with the work of the brush, then you can quickly get rid of dirt without harming the coins using this tool.

4 way: cooking in soda

Another way to "cook" a copper medallion to perfection is to boil it in water with 3-5 tablespoons of vinegar per half liter of volume. The final result is quite good, a small green coating disappears from the surface, and difficult areas can be finished with a brush using dry soda.

5 way: ammonia

If during the cleaning process one of the previous methods failed to achieve the desired result or the product initially has a large layer of plaque, then ammonia can be used. Coins are covered completely and remain in the bath until completely cleaned. Definitely, this method is very effective, but one of the most harsh on the surface, you can almost forget about the patina layer.

Method 6: cleaning with Trilon-B

Trilon-B (disodium salt of ethylenediaminetetraacetic acid) is a specially developed agent, the action of which is aimed at softening metal salts. Oxides and patina under Trilon are very easy to remove from the surface. Trilon-B perfectly copes with uniform contamination, but in the case when the plaque is located pointwise on the product, the part that was contaminated will become shiny, and other surfaces will lose their patina layer. By choosing Trilon cleaning, you can get a clean coin in a few minutes, without damaging the metal, as some salts and alkalis do.

7 way: electrolytic cleaning.

If you are not alien to various chemical cleaning methods, then you can resort to this tool. For this you will need:

A glass of cold water;
Stainless steel spoon;
Salt (small pinch);
A source direct current 9-18 volts;
Small clips - crocodiles;
Soda.

The first thing to start with is to prepare a saline solution, a copper medallion is lowered into it, to which a negative wire is attached in advance, the positive wire is attached to a spoon and also lowered into the water. Make sure that the coin and the spoon do not touch in the solution. After proper placement, the adapter can be plugged into the network, after a while the solution will begin to become cloudy, turning into the color of impurities that have descended from the surface of the product.

Important
You can check whether the coin has been cleaned or not by first disconnecting everything from the voltage, if the product has got rid of plaque, you can stop the coin from the clamp and place it in soda for a while to stop the ongoing reactions. This method is somewhat universal and will work for other coins as well.

You can clear your find in any of the above ways, each has been tested and each has its pros and cons, which one is better easy cleaning lemon or hard trilon, it's up to you. Do not forget that you can get acquainted with all the nuances only during the cleaning procedure at home, and if your coin is of exceptional rarity, for example, one of the royal coins, then you should resort to the help of professionals and not risk a valuable copy. Remember, these methods are only suitable for cleaning a copper coin, if you have one of the nickel copies or another metal, these methods will not work. After cleaning, take care of proper storage, and then the find will delight for many years.

Let's introduce you to in safe ways cleaning coins from an archaeological metal restorer with many years of experience in the Hermitage. An article about these methods of cleaning was posted in the book "The Past of Our Motherland in the Monuments of Numismatics". author useful material- an employee of the Hermitage O. V. Vasilyeva. Let's move on to the most useful excerpts from the text.

coin clearing- 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, 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 influence of chloride salts turns into gray-violet chloride, horn silver. On air copper alloys darken from oxidation, and silver - as a result of the formation of sulfide.

Restorers are always very careful about the restoration of numismatic monuments. In particular, they do right choice reagent necessary for cleaning from corrosion, since a reagent that is successfully used for some coins may be unsuitable for others and will lead to their destruction or distortion of their appearance. It is desirable to achieve and preserve a noble patina, a kind of certificate of antiquity of objects.

So, when starting to clean coins, you should first of all 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.

Cuprous chloride

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 is used: a glass vessel is filled with water by about 1/7 of the volume; a 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. Even 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 a colorless or slightly greenish liquid appear on the surface of the coins. Otherwise, the droplets do not come out: copper carbonate, oxide and copper oxide are stable in humid conditions (horn silver on silver coins also stable). And if copper chloride is found, it must be removed from the deepest pores and very thoroughly.

zalipukhi

Often, during excavations, coins are found boiled, forming a shapeless mass. We do not recommend disconnecting such coins by glowing and lowering them into cold water. To avoid losses, such a lump should be placed in a 5-10% sodium hydroxide solution and heated to 30-50 ° C. After that, the coins can be separated from each other, determine the condition of each of them and start cleaning.

Cleaning methods

The main ways of clearing coins are mechanical, chemical and electrochemical. During restoration, a combination of the mechanical method with others is practiced.

Machining consists in removing surface layers: earth, sand and individual corrosion bumps. It is produced using various brushes, scalpels and dental burs. various sizes. But when used roughly, they can easily cause scratches that will distort the inscription, images, etc.

copper coins

The chemical method, combined with the mechanical method, cleans coins covered with a thick layer of corrosion products, but retaining a metal base, as well as coins made of 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 action of ammonia on the metal will be destructive.

If copper coins are covered with salts consisting of copper carbonate (dark green), these deposits should be removed with a 5-10% solution of citric acid. 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 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.

The restorer often has to deal with fully mineralized coins that are not always preserved. The success of the treatment depends to a large extent on which compounds have replaced the metal as a result of complex mineralization processes. First, the surface deposits should be carefully removed. If in this way it is possible to reveal one or another ornament, inscription, etc., then this should be limited. If mechanical restoration did not open the coin, use a 5% solution of caustic soda or ammonium carbonate.

Attention! Since the degree of preservation of coins is different, it is difficult to give recommendations regarding the time of their residence in one or another reagent. Therefore, periodically removing the coins from the solution, you should gradually remove the softened layers mechanically, thus contributing to the acceleration of the cleaning process.

silver coins

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 a coin in a glass vessel or in a porcelain 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 brushing off the mechanically softened salts with brushes. You can also use a 5-10% solution of formic acid, preferably heated to 50-70 ° - 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% ammonia solution. In these solutions, horn silver softens, after which it is carefully removed mechanically.

A brass brush is a restorer's tool.

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 commonly 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 into them (like a grater). Formic acid of 5-10% concentration is taken as an electrolyte. A zinc or aluminum plate is placed at the bottom of the glass vessel. Several coins are laid out on the grated surface of the plate, which are covered with the grated 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, the coin is examined through a magnifying glass to determine the degree of its purification.

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. It is necessary to remove fatty substances from them with acetone, gasoline or alcohol and lower them into a 5-10% solution of citric or formic acid.

After cleaning

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 reacts neutrally according to the universal indicator. 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.

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 coins and medals not in heaps, but in separate cells of albums or in trays with compartments.

Additional information about the restoration of metal can be found in the books "Conservation and Restoration of Museum Collections" by M. V. Farmakovsky and "The Conservation of Antiquities and Works of Art" by H. D. Plenderlis.

Well, about more modern methods of cleaning coins using effective means read on "MDRegion" and look at our channel on YouTube.