How to clean different coins using electrolysis. Silver refining at home

Currently, there are many known methods for purifying metals, applicable both in the laboratory and at home. One of these methods is refining, which until recently was used exclusively at specialized enterprises using patented technologies.

What is refining

Typically, the term “refining” means high purity through a series of procedures to remove impurities. This process is carried out in several stages, at each of which certain physical and chemical methods are used to separate interfering substances. Precious metals are often purified in this way.

The raw materials for refining in this case can be jewelry scrap, “silver foam”, sludge after electrical purification of the relevant substances and spot gold.

Silver refining

This cleaning method is often used to obtain high-grade silver. In general, the procedure is no different from similar techniques carried out for other noble, ferrous or non-ferrous metals. For example, the refining of gold and silver or any platinum metals can be the same. Only in some cases the procedures differ.

Ways to carry out refining

In processing technology, silver refining is represented by three in different ways- metal can be purified from impurities by chemical, electrolytic or cupellation methods. Removal of excess chlorine is rarely used. The choice of technique is determined by the amount of silver processed and its condition. The characteristics of the production process also matter.

How the path is chosen

For initially high-grade silver, electrolytic refining is used. Typically, when using this method, there is daily production. Electrolysis helps to obtain silver of exceptional purity due to redox reactions, in which impurities do not enter during purification.

In the case when argentum is in the form of a solution (insoluble sulfates and chlorides), the most economical and convenient way to deposit the metal is the chemical (in some situations - electrochemical) method.

Low-grade alloys are most often separated using cupellation - in this case, it is easiest to increase the purity of the mixture.

Cupellation method

This type of refining requires a furnace with a cup-like (assay) crucible. The purification process uses lead, the melt of which with silver is oxidized in the presence of oxygen. All impurities, including the solvent, are separated from the noble metal, giving it relative purity: gold and platinum family metals remain in the alloy.

To carry out refining, the furnace must be preheated. A technical lead-silver mixture is placed in it, which is heated until completely melted. Atmospheric air flows are launched into the oven, causing oxidation of the content components. Upon completion of the heat treatment, the crucible is removed and poured into molds.

The inside of the oven is lined with marl - a type of clay enriched with limestone and having a porous structure. It absorbs lead oxides formed during the refining process, since the latter are prone to evaporation when exposed to air currents. At the output, after oxidation of impurities, an alloy with a rainbow-iridescent surface is obtained. When it cracks, a bright silver sheen can be seen in the mixture, which indicates the completion of refining.

Cupellation is considered the most rough method purification due to the fact that not complete removal of impurities is achieved: all noble metals in the alloy remain in place. Refining of gold, silver and their separation is carried out by other methods.

Electrolysis method

Electrolysis as a refining method is carried out with the consciousness of a double electronic layer: the anode of the process becomes a contaminated fragment of silver, placed in a bag, and the cathode - thin plates formed from non-corrosive steel. The electrodes are immersed in a solution of nitrate of the metal being purified (ion concentration up to 50 mg/ml), added with a density of 1.5 g/l, and an electric current is passed.

Undissolved silver fragments, as well as contaminants, collect in the anode bags. A pure sample in microcrystalline form is collected in the cathode space. The volume of released silver may increase towards the other pole of the system, causing a short circuit. To prevent such a situation, the grown crystalline fragments, when stirring the solution, break off parallel to the electrodes near the cathode location. The resulting silver is recovered as sediment and subsequently cast into bars. It is important to replace the electrolyte on time, since if copper is present as an impurity, at the end of the desired process, its deposition on the cathode on top of the noble metal will begin.

If the silver solution behaves as a galvanic cell, the electrolytic method is also most effective for separating the metal. The anode can be graphite or non-corrosive (alloys), the cathode can be stainless steel. The voltage in the element is set at a level of no more than 2 V. The reaction itself is carried out until all the silver is deposited.

Chemical refining

Silver can be extracted from solutions of salts or colloids using chemical technologies. The process is multi-stage. To carry out the procedure, sodium sulfite is required, when added, an exchange reaction occurs with the formation of a black precipitate of a new salt of the noble metal. Upon completion of the interaction, ammonia or table salt is added to the resulting solution. The mixture is allowed to settle until there is a clear fractional separation - a cloudy and transparent part should form. Silver is considered to be completely deposited if the additional introduction of salts does not cause turbidity.

There are two ways to isolate pure metal from chloride - dry and wet.

Carbonate method for separating silver from chloride

This technology involves obtaining pure silver from dried chloride - the substance is combined with an equilibrium amount of sodium carbonate. In the crucible, the resulting mixture is heated (the bowl only needs to be filled halfway due to the increase in the volume of the contents due to the release of gas). After the formation of volatile products is complete, the process temperature increases, reaching the values ​​necessary for smooth melting.

After the system has cooled, the silver is removed and re-smelted, after which the product can be considered ready. A negative point may be the fact that technical soda has a negative effect on the condition of the crucible. The main advantage of this method of chemical refining is its speed.

Reductive method for separating silver from chloride

To restore silver from solution, you can take different sets reagents - sulfuric acid with zinc or iron or hydrochloric acid with the same metals, including aluminum.

One of the elements is introduced into the chloride medium. The selected acid with a concentration of 0.2 parts by mass is added to the resulting sludge. You can add the solution in parts, monitoring the degree of progress of the reaction and adding the remainder when it is completed. A qualitative sign of interaction in this case is the release of hydrogen - gas ceases to form at the moment of complete dissolution of the metal or disappearance of the acid (its consumption can be certified by indicator paper).

The separation of silver from salt is completed when the system becomes similar in color to lead. After this, acid is added to bring the remaining fragments of unnecessary metals into solution (large parts are manually removed). The remaining powder substance (the so-called silver cement) is cleaned with distilled water, dried and melted.

Chlorine refining

The method is based on the assumption that silver and base metals react in a chlorine atmosphere faster than gold and the platinum family of elements. This makes it possible to separate the latter substances from the substance being purified (in refining technology, the most labor-intensive process is the separation of noble alloys).

The molten rough gold is passed through chlorine gas. The interaction begins with impurity elements of a base type, then silver passes into the form of the compound, which can subsequently be isolated by other refining methods. Chlorides in the mixture float to the surface due to the lower density of salts compared to metals.

Refining in other cases

If there is a copper impurity in silver, it is rational to speak not of an alloy, but of a mixture of metals (can be presented in the form of shavings). Then nitrogen can dissolve the base metal. Concentrated substances are used cold or hot (the speed of the reaction depends on this).

To remove the silver shell from products, the mixture is heated over an alcohol lamp or in a water bath. At temperatures below 50-60 degrees, you can use glass or porcelain dishes. In the same way, you can separate the metal being purified from nickel, tin or lead.

Silver refining at home

All the methods described above are theoretically suitable for home use, provided that you have special equipment and experience. For beginners, it is better to try the electrolytic method. This is usually how silver is refined from contacts.

The procedure consists of 3 stages. This is the dissolution of silver in nitric acid, its cementation and fusion, and the direct refining of silver at home by electrolysis.

Dissolution with nitric acid

Silver nitrate is prepared immediately for the entire process - usually 50 grams of metal per liter of solvent is taken (to obtain this ratio, 32 g of scrap is dissolved in 80 g of hydrogenated nitric oxide V). The acid must be diluted in equal proportions with water and mixed with a glass rod. It is possible to refining silver with nitrate when mixed with an electrolyte (with a reaction of the medium less than 7) to obtain the same HNO3. Pieces of silver are added to the resulting solution. The mixture must be left for 10-11 hours, since the transition of the metal into a suspended state will not occur immediately. Violent release of red-brown gas is possible. If the solution acquires bluish or greenish tints, this indicates the presence of vitriol or iron impurities. Refining silver with nitric acid works better in cases where there is no intense coloration.

Extraction of silver cement

Copper bars are added to the mixture to carry out a substitution reaction with silver. Almost immediately, noble metal begins to precipitate on the surface of the red metal, which should be periodically shaken into the solution to speed up the process. If the bars completely dissolve, they need to be replaced with new ones. The end of the reaction in this case is considered to be cooling of the solution and its fractional separation into silver-cement and bluish liquid parts.

Filtration

To separate the metal from the solution, a funnel is used and the solution and cement are poured into a specially prepared container: the copper salt flows through a layer of parchment, and the silver remains on the surface. Subsequently, it is necessary to rinse the filtrate another 5 times with distilled water.

There is likely to be some remaining silver in the solution. To extract it, table salt is added to copper until a curdled sediment forms.

Silver cement is dried. Melting is carried out in a crucible, the use of which is not intended for working with purer samples. The sample must be heated evenly to avoid flying silver or oxidized dust. You can add baking soda and borax, mixed in equal proportions, to the surface of the melt - the composition will create a glassy film over the metal that protects against loss.

The resulting substance is of low quality. To clean it more thoroughly, electrolysis of silver is required. Refining in this case is carried out according to the method already described above - for this it is convenient to melt the metal into granules.

Safety precautions

It is important that the room has good ventilation. For protection, it is recommended to use gloves, a gown and protective glasses. To avoid acid splashing, the concentrate itself is added to the water, and not vice versa. Obtaining HNO3 by exchange reaction is the safest method by which silver can be refined. In this case, ammonium nitrate is mixed with an electrolyte (the reaction of the medium is less than 7). Chemical glassware should be tested for temperature resistance, since the heat of the process can exceed 100 degrees. No more than a third of the vessel is filled with the solution to avoid splashing of the acid.

Results

Silver refining is not a complicated procedure if you have certain experience and equipment. If you follow safety precautions, it can be carried out outside of laboratory conditions.

To obtain metal of the highest standard, it is convenient to use silver refining by electrolysis at home, since this method minimizes the risk of impurities due to the use of current.

To clean coins using this method we need: power supply
12 volt (suitable from radio charger
phone or mobile) 2 crocodiles (can be used instead of crocodiles
secure with the wire of the charger itself) plastic or glass
reservoir (bath in which electrolysis will occur, you can
use a regular glass), salt or soda.

First, let's take the power supply. Cut the plug at the end
devices, separate the 2 wires and strip the ends
wires from insulation. Next we take our container (the container is not
should be metal) fill it with water. Water
there should be so much that it could cover our coin
and cleaned power supply wires. Add to water
salt or soda. (Below will be an experiment with the addition of
water instead of salt water.) In order to find out
which end of the wire to attach a coin to - lower it, free from
wire insulation, in water and observed from
which of them will cause bubbles to appear. TO
to the end from which the bubbles will come, we and
We attach our coin to another - a metal object.
As an iron object at the end of the wire you can
use an unnecessary spoon, key, blade. Attention after the process
electrolysis objects (iron) attached to the end of the wire
will fall into complete disrepair. Don't use those
items that you may need in the future!

This cleaning method is considered aggressive. So to begin with
practice on objects that don't represent
numismatic or archaeological value. In the future you
You will understand whether this method suits you or not.

Below is this method of cleaning Garry coins by a forum participant
violity using soda instead of salt
detailed description.

I'd like to add a couple useful tips to this topic.
There is one thing!-- Why use saline solution? At first I
and I tried to experiment with this myself
solution. I measured time and currents, while controlling coins every
10–15 seconds. Standing in the bathtub over this miracle of modern
progress (oxidizes over centuries, is removed in minutes, and then
seconds) from a young thinker, slowly turned into
a cackling old man. And the whole point is in the selection (albeit
not significant) chlorine. Symptoms disappear quickly after
an hour or two, or even earlier (someone
can say, like chlorine in small concentrations is even useful). But
I didn’t poison myself anymore. One search colleague - (for
thank him so much) he advised me to use baking soda. And oh
a miracle - this is truly the right electrolyte. There is zero odor, the gas is harmless
(carbon dioxide), the solution is a pleasant blackish-brown color, and not
poisonous green and when you pour it into
the sink is much easier to wash the container. Coins after saline solution
after a while they often become covered with a purple-brown coating or brilliant green appears
(by the way, electrolysis is probably one of the effective ways to kill this
greens -IMHO), this doesn’t happen after soda. Yes
soda is much more neutral for fingers. It was
once.

Two - something to attach as an electrode (a piece
iron, spoon, Ptr-ovskaya sleeve, gold ring) All metals have
disadvantage, it oxidizes, while dissolving in
solution. In particular, the cartridge vitriol and the reaction
becomes slow until it stops altogether.
file or sandpaper and again all in a circle. If you clean one
coin, there is no particular discomfort from the sleeve
it will - it won’t have time to oxidize, but if you need to clean the Augean
stables, then the best option is GRAPHITE! For experiment, you can disassemble
Chinese battery (not alkaline) and up to
she will live on ten coins. But then her hands... You can take a trolleybus
a brush (which is located near the TTU or just along the road) and
saw off a piece from it. Still, the best option is a brush
from electric motors. Durable, different sizes with
convenient wire for connection and in addition
long-lasting.

Yes
and crocodile clips, ala de China for 50 kopecks, this
nonsense. Look at radio markets, flea markets or from a TV specialist
Uncle Fedot's Soviets, from the so-called switch tseshki.
photo below: lower nibbler, worked out for about 30–40 coins
just wiped with a cloth, without using fur. means. Compare it
with the new one and those you have lying around
Houses.

It is advisable to have an adjustable power supply, I
I use a homemade product from 1.2 to 27 Vs with current up to
3 A. Holding the object with a crocodile, I give the maximum for a short time and
after 5–10 seconds, when gas begins to evolve from
the entire area of ​​the product (and not just the clamp)
I reduce it to 6–9 V. And it’s not at all necessary to “boil”
coin constantly - just alternate the method [layer blasting-cleaning]
several times in a couple of minutes to achieve the desired
result.

The use of various cleaning brushes is also
necessary in our business. Previously, in addition to dental I others
I didn’t know, but now I have 5–7 different forms of them and
appointments. Separately, I would like to highlight the cleaning brush
suede shoes like “TWIST” or other jewelry
the same type costs 5-15 times more expensive. It is advisable not to take
completely metallized, and the one in which there are
and nylon hairs. Although for superficial cleaning of all kinds of pieces of iron
the first one rules more. Try using it in a cleaning complex
objects and you will like the result. Does not remove patina
-unless, of course, you try to make fire out of a coin.

Cleaning coins with Electrolysis!

(a manual for making a kit for cleaning coins using the electrochemical method)

Warning.

While electrolysis is a popular form of cleaning ancient metal objects, especially coins, there are certain dangers inherent in using 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 safety glasses and rubber gloves. Even though the risk of electrocution is extremely low, you should never be complacent when using any electrical device.

Electrolysis - quick way cleaning coins. What takes months with olive oil can be done in minutes with electrolysis. Of course, this increases the risk of your coin being destroyed. Even with great care, you may end up with an unsatisfactory result, although the dirty coin initially showed great promise. Since electrolysis strips the coin of its patina, you are playing gambling, the result of which depends on how good the condition of the oneta core is. Sometimes it happens that a coin consists entirely of one patina.

Assembling the electrolysis kit.

The first thing you need is an old power supply with a voltage of 6 to 12 volts or buy one from the market universal block power supply for receivers, tape recorders, etc. (for 4 plugs). Higher voltage increases the risk of electrocution with little increase in the efficiency of the cleaning process.
Cut the plugs at the end of the power supply wire. Divide the ends of the wire into two parts and strip the ends of the insulation. Twist the copper strands and, if possible, connect (solder) them to metal clamps (such as alligator clips).
Put all this aside and take a not very deep plastic bowl (photo bath). Fill it with water to the depth required to clean the coin you have chosen, and dissolve table salt or baking soda in it: 1 tablespoon per 0.5 liter of water (preferably soda). Plug in the power supply, holding the two clamps far apart from each other at insulated areas. If they touch, a short circuit will occur and the power supply will fail. Dip the clamps into the solution and note one that will release gas and hiss (this is +) on the other, respectively (-). You must connect this positive clip to the coin (for quick “break” cleaning). Connect the other clamp to
metal object. It could be something small, like a key or a spoon. Do not use copper or brass items for this as they do not work very well. The best option there will be a reverse connection, connect the clamp on which there will be no hissing (-) to a coin, and (+) where there will be hissing, connect to a metal object.

Note:

The “disruptive type” of electrolysis, found on (+), with speed and efficiency, has one side effect, the molecules of the metal itself are “knocked out” from the surface of the object, therefore it is DANGEROUS when working with valuable small items, it “ripples” the field and finishes off the remnants of the relief.
The finding on (-) is the “reductive type” of electrolysis. The process is much slower, and it even involves some “recovery” of the metal from its oxides. But this “restored” metal has a porous structure, is soft and still washes off along with the dirt. So, it’s a pity, but it won’t be possible to convert even a fraction of the relief back into metal, but it is absolutely harmless in relation to the metal core, softening only dirt and oxides on the object, and any kind of patina too. I repeat once again - it is better to keep the item being cleaned on (-)! On (+) it dissolves forming cavities. You can keep it at minus for at least a day, nothing will happen to the metal of the coin. Then the resulting thick layer of “shaggy” soft blackish is washed off under hot water, with a trimmed toothbrush and soap.

You now have an electrolysis kit. Cleaning process.

Dip both clips into the solution and your coin should start to fizz and bubble. Depending on how large the layer of dirt and oxides is on your coin, the cleaning process should last from half a minute to several minutes (option for “breakdown type” cleaning) and from 40 minutes to a day (for “restorative type” cleaning). The coin should bubble vigorously. If the gas evolution is small, then this is also not bad, the process will just go slower. The rate of electrolysis can be increased by adding more salt or soda to the solution or by bringing the clamps closer together without actually touching them.
Remove the coin from the solution after unplugging the device and clean it with a toothbrush and 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 stains may not yield to electrolysis at all, in which case they must be removed with a knife or other mechanical tool.
After a while, you will notice that the solution in the vessel 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.
Good luck! :-)

Cleaning coins with electrolysis is a risky method, especially for a beginner, so you should start with coins that are not particularly valuable. Even ordinary soda can ruin a coin, but electrolysis can cause serious harm to money - completely erase the patina or cause irreparable damage to the coin. It is impossible to get rid of such damage, which means that the value of the coin will decrease.

Cleaning a coin by electrolysis

What is needed for electrolysis?

Cleaning by electrolysis will require minor economic costs. The duration of the procedure is from 10 to 40 minutes, but sometimes cleaning can last for an hour. You should not leave money unattended, soak it in a solution or clean it by electrolysis throughout the day.

For the procedure you will need:

1. Two alligator clips or applicator clips, you can purchase them at a hardware store.
2. Deep dishes made of glass or plastic; if you don’t have one, a regular glass will do.
3. Adapter with power from 6 to 18 amperes.
4. Distilled or purified water from a bottle.
5. Baking soda or salt.
6. Concentrated lemon juice.
7. Stainless steel spoon.

Carrying out such a procedure requires the availability of protective equipment. You will need:

1. Rubber gloves.
2. Safety glasses or mask.

The electrolysis process is usually accompanied by the release of gas, so the procedure should be carried out in a well-ventilated area.

If salt was added to the solution to clean money, then during electrolysis the salt ions break down into sodium and chlorine. Chlorine is released in the form of gas. Since contact with this substance is dangerous to human life and health, it is recommended to carry out the procedure with a mask or use soda instead of salt.

Cleanse banknotes Use caution; the adapter may become hot during cleaning. If it gets very hot, then you should not leave it without attention - there is a high risk of fire.

Particular attention should be paid to the solution. You need to add 2 tablespoons of soda or salt to the water. Cleaning coins by electrolysis can be done by adding lemon juice to the solution, 20–30 grams is enough. Lemon juice will increase the effectiveness of the procedure and help remove dirt from the metal surface.

How is the procedure done?

Step-by-step cleaning description:

• first, disconnect the stamp from the adapter and expose the wires;
• then install clamps to each wire;
• prepare a solution for the procedure;
• find out which terminal the negative charge goes to and which the positive charge goes to.

A wire with a positive charge should go to the spoon, and a wire with a negative charge should go to the coin. If you can’t figure out the wires yourself and you don’t have a tester at hand, you need to place a spoon and a coin in the water so that they don’t touch each other. If a wire carrying negative current is connected to a spoon, it will begin to bubble; if this wire is connected to a coin, it will begin to bubble.

Electrolysis cleaning steps

The minus is not capable of harming the metal of the coin, but it is still worth carefully monitoring its condition. Periodically remove the product from the solution and check the degree of cleaning.

Observing the process, you can see how dirt peels off the surface of the metal and moves away. Cleaning coins involves changing the color of the solution. During the procedure, it is able to change color, darken and turn black. This happens not only because the dirt moves away from the metal, but also because the clamps in the solution oxidize.

After the procedure, it would be useful to polish the money - they must be rinsed under a stream of water, and the surface cleaned with a toothbrush. The surface of the metal is then polished using a piece of suede. If there is no suede, then wool without lint and pellets will do.

During the cleaning process, you may notice how the surface of the coin becomes covered with black flakes. You can easily get rid of them by brushing: for this you need to periodically check the degree of contamination of the product, removing it from the solution every 15 minutes.

Don't go overboard as cleaning with electrolysis can cost you money. Minor damage may form on the metal surface and the patina will disappear.

If the dirt stuck to the coin cannot be cleaned, then you should not experiment and repeat the procedure using electrolysis; it is better to give the coin to a restorer for cleaning.

Peculiarities

Cleaning copper coins by electrolysis has a number of nuances that you should know about before starting the procedure:

• lemon juice will enhance the effectiveness of the procedure, but the acid can harm the metal;
• adding soda to water will also make cleaning more productive, but salt is more effective;
• the release of gas and the appearance of bubbles indicates that the cleaning process has begun;
• If the water does not bubble too actively, then the reason lies in the power of the adapter.

The work of a restorer is difficult to compare with cleaning by electrolysis, but if there are no other options, then you can use a similar procedure.

Coins that are valuable should not be cleaned this way. Before carrying out the procedure, you still need to practice on cheaper coins.

In general, the method is not bad and quite effective, but it is not recommended to risk a valuable piece of the collection. You can try cleaning the metal with a brush or simply washing the coin in warm water with soap.

Metals oxidize for several reasons, and sometimes you should leave a coin in its current state if there is a risk that cleaning will do more harm than good to the item. The collector is able to clean the coin himself after purchasing it.

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'll talk about them in this article.

Types of coin cleaning

Depending on the degree of contamination, characteristics of the material and other factors, it is necessary to decide on 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. If you have concentrated hydrochloric acid, you can make a special bath with a solution and immerse coins in it. 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 consolidate and enhance the effect obtained with any dishwashing detergent; ordinary laundry soap will also give a good result. Coins with minor stains should be soaked in the resulting solution for 2-3 hours. Coins with heavy deposits can be kept in the prepared liquid for about a day.

How to clean a coin with soda

Cleaning with soda is an alkaline method of removing dirt and is suitable for items made of low-grade copper and silver. The process is carried out easily, without creating special conditions. First, a paste is formed from a spoon of soda and a small amount of water, then the mixture is applied to the coin. Dirt is removed with a regular soft brush. Baking soda can also be used after acid cleaning to extinguish the reaction.

How to clean a coin with vinegar

Cleaning using vinegar or citric acid Suitable for hard metals. A teaspoon of soda is added to the vinegar solution and the liquids are mixed. Coins are immersed in the resulting bath and left there until the stains disappear, and then treated with soap, warm water and a soft brush. If the dirt is not washed away, the procedure is repeated.

It is not advisable to use this method for coins made of gold, silver or copper.

Cleaning coins by electrolysis

Electrolysis- the most dangerous, but also the most quick method eliminating defects. Cleaning is done by applying current to a lightly salted 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 silver items, pure copper or alloys containing it. The coin is dipped in ammonia for the time required 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 fabric, etc.). This method is quite effective and removes any contaminants, but there is a risk of damaging the surface of the products.

Boiling down 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 pan with hot oil for 10 minutes(it is more convenient to clean in a special lattice box on a chain). After cooking, you need to wash the products with a brush and soap and remove any remaining oil by thoroughly boiling the coins in distilled water.

After cooking, the specimens acquire radiance and shine, but a noble patina disappears from them, giving the products additional value. Rare coins It is better not to expose yourself to such influence.

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 damage it. For example, mechanical impact using acidol or jewelry paste leaves scratches and helps erase small details of drawings.

Cleaning gold coins

Gold coins do not require aggressive cleaning. If dirt appears on the products, it will be enough to wash them with warm soapy water, rinse with water and dry. You should not rub gold coins vigorously because even ordinary fabric leaves on noble metal small scratches.

Cleaning silver coins

Choosing the appropriate cleaning method for your silverware depends on on the sample and degree of oxidation of the metal. High-grade 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 speed up if the liquid is brought to a boil several times and the oxidized areas are treated with a soft brush.

High-grade coins with minor 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 should be covered with the mixture and rubbed with your fingers or a brush.

Suitable for cleaning low-grade silver coins Trilon B solution. When the green layer disappears from the surface of the coin, you can continue the process using a special mixture for silver of a certain standard.

Cleaning Copper Coins

Copper products are susceptible to the formation of a patina layer 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 to clean the coin. Patina protects metal from corrosion and gives the coin a noble appearance. To remove traces of touch and grease, the product can be washed in warm water.

It is better to clean corroded coins using aggressive reagents (acetic and citric acid, trilon B). They will gradually separate the damaged layer of metal without affecting the solid base. To process weakly oxidized coins, soaking them in the solution for several hours will be sufficient, while highly oxidized coins can be left for a day or more.

Cleaning bronze coins

Bronze products are cleaned according to the same principle as copper ones. But you need to keep in mind that ammonia changes bronze color. The metal may turn brown or even black. Shine bronze coin can be easily restored by applying toothpaste to its surface and washing it in warm water. After cleaning, you need to dry the items by wrapping them in two layers of soft cloth and paper napkin.

Sulfuric and nitric acids should not be used to clean copper or silver coins as they destroy fine details of the design.

Coin Cleaning Tools and Supplies

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 dishes, tweezers;
• reagents (soap, distilled water, soda, linseed oil 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, 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 wiped 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 excess layers are removed carefully and gently.

Exposure using caustic soda is a very quick method, but suitable not for all coins. Both products with a relatively flat field and those with an uneven thin film can be cleaned well.

When preparing caustic soda solution, safety precautions must be observed. Dissolve the granules (1 sachet per 500 ml) only in distilled cold water, take the coin with tweezers and be sure to work with gloves.

The product is immersed in the solution for 10 minutes. Then washed with water. After this, the softened oxides can be easily removed with a brush.

If during the cleaning process the oxide on the product turns blue or green, the process must be interrupted immediately.

Cleaning Copper Coins

Careless cleaning copper coin may cause chips and pits to appear on its surface. Depending on the type of corrosion, the appropriate method of exposure is selected. The reddish coating is removed with a five percent ammonia solution or ammonium carbonate. You need to hold the coin in ammonia solution no more than 1-2 minutes. Green plaque can be removed with a solution of citric or acetic acid. The yellowish coating is dissolved with a 10% acetic acid solution.

After cleaning the coin using any of the above methods, it must be boil in distilled water. After several boils, you can check whether the coin is completely clean by dropping a 1.7% solution of silver azone into the water. If after this the water remains clear, then the cleaning process must be completed.

After cleaning, the product must be thoroughly dried. You can place the specimen 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, you can apply artificial to make the product attractive appearance. Per liter of distilled water, add 50 g of copper sulfate and 5 g of potassium permanganate. The resulting solution is heated to 80-90 degrees. Coins are placed in the heated liquid. Next, you should turn the coins over from time to time and wait for the desired color to appear. After the procedure, the coins need to be dried and coated with a 1:1 mixture of alcohol and benzene to protect them from corrosion. About artificial patina You can also read in the article “”

Electrochemical cleaning

Electrolysis– fast and effective way eliminate dirt, but its use is associated with some dangers inherent in the operation of any electrical device. The device should be used in a well-ventilated and lit area. Before carrying out the process, you must wear protective gloves And glasses.

When using electrolysis, the risk of spoiling a coin increases significantly (compared to other methods - several times). 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 cleared of insulation. The copper strands must be twisted, soldered, or attached to metal clamps. Next, take a shallow plastic container and fill it with saline or soda solution (1 tbsp per 0.5 l).

Turn on the power supply. The clamps are held at isolated places at a distance from each other (if they come into contact, a short circuit will damage the power supply). The clamps must be immersed in a container with a solution. On one of them there will be hissing and gas release - this is “+”.

It needs to be connected to a coin, and the second clamp (respectively “-”) is connected to a small metal object (for example, a spoon or a key).

The second option is a reverse connection. The positive terminal is connected to a metal object, and the negative terminal is connected 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 “+” is connected to the coin) and from 40 minutes to 4 hours(if “-” is connected).

Having finished cleaning, you should turn off the device from the network, remove the coin from the solution and clean it with a brush and a small amount of liquid soap. To remove special, complex contaminants, the procedure will have to be repeated. The solution will become dirty after some time and will need to be replaced to perform repeated electrolysis.

Summing up the topic of cleaning

A method of cleaning coins that would allow them to return exactly to their original appearance, doesn't exist, but with due diligence you can significantly improve the condition of the coins. The safest option is to use a soap solution.

More serious stains may require soaking coins in the solution for a long time. Sometimes you have to wait several weeks for results.

With prolonged soaking the 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. This cleaning method is ideal for gold coins.

After the procedure, the product is dried and wrapped in a soft cloth. Mechanical cleaning is also considered a relatively safe method, but is absolutely not suitable for soft metals that are easily scratched.

Main task– do not completely spoil the coin and do not deprive it of its noble patina. Some specimens are better not to be cleaned at all, but simply washed. Before starting work, it is recommended to practice on the most simple coins. It is imperative to follow safety regulations (chemical cleaning methods can be hazardous to health).