How is copper oxidized?

Are copper and brass drip tips dangerous? Answered by ViVA la Cloud

Copper Goon on RX200

On June 10, 1958, 18 factory workers in Liverpool drank tea. Their stomachs hurt, headaches and weakness appeared. And then they fainted. Two were in such serious condition that they had to be taken to the hospital.

In 1988, a 7-month-old girl was hospitalized due to liver failure. The doctors could not figure out what was wrong. Three months later, the child’s liver failed and the patient died

In 2007, a man built a homemade smoking pipe. He tried the device, breathing air through it. The inventor was brought to the hospital with acute chest pain. There they cleaned out his lungs, but even after three months the pain remained.

All these cases are united by the metal - copper. Factory workers boiled water in a copper container, from which, due to the high temperature, metal particles got into the drink. Copper impurities were also found in the water that the entire family of the deceased girl drank. The needleworker finally created his pipe all from the same copper.

Copper is a metal with a pinkish color. It heats up very well - almost six times faster than steel. As a result, dishes are made from copper - however, the metal always has a special internal coating. Copper is also a very good conductor of current, which is why it is used to make electrical wires.

Example of copper utensils Certificate confirming the presence of 99.9% copper in the composition of the utensils

In addition to pure copper, its alloys are also used. Other metals—zinc, tin, lead, nickel, or others—are added to improve the physical, mechanical, and chemical properties of the alloy. The most famous copper alloys are bronze and brass. Guns, bells and statues are cast from bronze, and gas and water pipes are made. Brass is used in mechanical engineering and shipbuilding for the manufacture of parts. Jewelry and watches are also made from brass: it looks like gold.

Dangers

Copper has a significant effect on the liver. Those who suffer from liver diseases should be especially sensitive to this issue - in these cases, copper is poorly processed by the body, accumulating on its own, without additional influences.

Bronze bell Brass machine parts Brass
plumbing and shipbuilding parts Brass jewelry

Copper oxides are mainly dangerous. They form when copper oxidizes. Leave the copper mod or dripper to stand for a couple of days - the brownish metal is that same oxide (or oxide). Its particles very easily come off the surface of the metal, including getting into the lungs. Inhaling copper can cause poisoning and, as a result, “copper fever.” Symptoms include chills, high fever, heavy sweating and leg cramps.

Copper oxides based on Kennedy 22 Green copper oxides on the body of the mod

Brass oxidizes less due to the addition of other metals. Despite this, the copper contained in the composition is dangerous. Copper oxides appear when a brass product comes into contact with sweaty skin.

Brass oxidizes, and after a while green marks appear on the skin - these are copper oxides. They are toxic - frequent contact with skin may cause skin diseases. The epidermis in the affected area turns red and blisters may appear.

Less commonly, in case of contact with copper oxide, eczema, an acute type of dermatitis, may appear.

Dermatitis Eczema

How to deal with poisoning

In our age of development of science and technology, copper is used less and less, and it is now almost impossible to get poisoned by accidentally pouring soup into a copper plate: most cases were recorded in the mid-to-late 20th century.

  However, caution should be exercised when using copper or brass mods and atomizers: there are known cases of group poisoning with copper almost “out of the blue.”

If symptoms occur, you should seek medical help, go out into the fresh air, take a horizontal position - and drink strong tea. Just don't brew it in copper containers.

Authors: Aldian Dadyanov and Ivan Romanchuk.

Typo - Ctrl + Enter4 July 2017, 14:54

Source: https://vivalacloud.ru/2017/07/brass-copper-harm/

Copper corrosion

Copper corrosion is its destruction under the influence of the environment.

Copper and its alloys are widely used in many industries. This is due to the high corrosion resistance of this metal, thermal conductivity, and electrical conductivity. Copper is perfectly processed mechanically and soldered.

Significant corrosion of copper is observed in oxidizing acids, aerated solutions that contain NH4+, CN- and other ions that can form complexes with copper.

Copper corrosion in water

The corrosion rate of copper in water largely depends on the presence of oxide films on the surface.

In rapidly moving aqueous solutions and water, copper is subject to a type of destruction called impact corrosion. The rate of impact corrosion of copper is highly dependent on the amount of dissolved oxygen.

If the water is highly aerated, impact corrosion of copper proceeds intensively, but if it is deoxygenated, the destruction is insignificant. Copper corrosion in aerated water increases with decreasing pH and increasing concentration of chlorine ions.

The rate of copper corrosion in water depends on the climate zone. In the tropics, the rate of destruction is slightly higher.

A special feature of copper washed by sea water is that it is one of the few metals that are not susceptible to fouling by microorganisms. Copper ions are harmful to them.

Pipelines for supplying water to homes are often made from pure copper. They are reliable and last a very long time.

In the presence of dissolved carbonic and other acids in water, copper gradually corrodes, and copper corrosion products stain plumbing equipment.

If water passing through copper pipes comes into contact with iron, aluminum or galvanized steel, then the corrosion of these metals increases significantly. Copper ions are deposited on the surface of these metals, forming corrosive galvanic cells.

To eliminate the harmful effects of water from copper pipes on other metals, tinned copper is used. The inside of the copper pipeline is coated with tin. The tin coating must be non-porous to avoid the formation of a galvanic element (tin is a cathode in relation to copper).

Corrosion of tinned copper

Tinned copper has excellent corrosion resistance. Tinned copper serves well even under the influence of rain, hail, snow, and is not sensitive to changes in ambient temperature. Atmospheric corrosion of tinned copper is very negligible.

The tin coating is an anode in relation to copper, because has a more electronegative potential. If there are no flaws on it (pores, cracks, scratches) through which copper comes into contact with the atmosphere, it will last a very long time.

If coating defects are present, atmospheric corrosion of tinned copper proceeds through the following reactions:

A: Sn - 2e→ Sn2+ - tin oxidation;

K: 2 H2O + O2 + 4e → 4 OH- - reduction of copper.

2 Sn + 2 H2O + O2 → 2 Sn(OH)2

High-quality tin plating extends the life of tinned copper to 100 years or more.

Atmospheric corrosion of copper

Under atmospheric conditions, copper is highly resistant to corrosion. In dry air, the surface of copper remains almost unchanged. And upon contact with moist air, an insoluble film is formed, consisting of copper corrosion products such as CuCO3•Cu(OH)2.

2Cu + H2O + CO2 + O2 → CuCO3•Cu(OH)2.

Depending on the composition of the environment and many other factors, a very thin protective film consisting of copper oxides and pure copper oxide is first formed on the copper surface in the atmosphere. The formation time of this film can reach several years. The surface darkens a little and becomes brownish. Sometimes the film can be almost black (largely depends on the composition of the corrosive environment).

After the formation of the oxide layer, copper salts with a greenish tint begin to accumulate on the surface. The resulting oxide of copper and salt is also called patina. The color of the patina ranges from light brown to black and green. Depends on the quality of surface treatment, the composition of the metal itself and the environment, the time of contact with the corrosive environment (from internal and external factors).

Copper oxide is red-brown in color, copper oxide is black. Blue, green, blue and other shades of patina are caused by various copper minerals (sulfates, carbonates, chlorides, etc.). Patina is neutral in relation to the base metal, i.e. does not have a harmful effect on copper (except copper chloride).

Salts and oxides that form patina are insoluble in water and have natural decorative and protective properties in relation to the copper surface.

The presence of carbon dioxide in humid air leads to the formation of a mixture on the surface, which is also called malachite. Sulfides and chlorides in the air destroy malachite. This accelerates atmospheric corrosion of copper.

Copper corrosion in soil

Copper corrosion in soil is highly dependent on the pH value of the soil. The more alkaline or acidic the soil, the faster the corrosion of copper in the soil occurs. Aeration and soil moisture have a less strong influence. When the soil is highly saturated with microorganisms, the corrosion of copper and its alloys increases. This is explained by the fact that some of them, in the course of their life, produce hydrogen sulfide, which destroys the protective oxide film.

The products of soil corrosion of copper and its alloys are more complex in composition than those resulting from atmospheric corrosion and have a layered structure.

If a copper product lay in the soil for a very long time, it could completely turn into a loose light green mass consisting of copper corrosion products. If the product remains in the soil for a short time, only a small layer of patina can be observed, which can be easily removed mechanically.

Copper is stable in the following environments:

- atmosphere;

- sea water;

— hot and cold fresh water;

- under certain conditions, being in contact with halogens;

- non-oxidizing acids, hot and cold deaerated dilute solutions of H3PO4, H2SO4, acetic acid.

Copper is unstable in the following environments:

- sulfur, hydrogen sulfide, some other sulfur compounds;

- oxidizing acids, aerated non-oxidizing (also carbon), hot, cold H2SO4 concentrate,

Cu + 2H2SO4 → CuSO4 + SO2 + 2H2O – hot concentrate,

Cu + H2SO4 → CuO + SO2 + H2O – cold concentrate;

— solutions of oxidizing salts of heavy metals (Fe2(SO4)3, FeCl3);

— aerated waters, fast-moving aqueous solutions, aggressive waters (low content of magnesium and calcium ions, high content of oxygen, carbon dioxide);

- amines, NH4OH (containing oxygen).

Source: https://www.okorrozii.com/korrozia-medi.html

Methods for blackening copper at home

Copper is a metal that has low activity and for this reason is often used for decorative purposes. Copper is used to make jewelry, home decoration, art, furniture and much more.

The metal surface oxidizes under the influence of oxygen, but due to its low activity, this may take decades. The consequence of this reaction is patina - a surface film that most often has a greenish tint.

Patina prevents the metal from being damaged, so it is important to know how to blacken copper at home.

Copper before and after blackening

There are two types of reactions that lead to the formation of films on the surface of copper:

• oxidation - the process of formation of oxides and oxides, elements containing oxygen;
• patination - a film is formed under the influence of sulfur and chlorine.

If you dip a copper piece in a solution designed to create a patina on its surface, it will immediately be transformed and, while sparkling new, will look like an antique. There are two main types of methods by which this effect is achieved, some are based on improvised means, while others require chemical solutions. They can be dangerous, so you need to work in compliance with all safety regulations. The room must have a fume hood.

Before you start blackening, you need to prepare the metal: clean, degrease, rinse and dry. For drying, do not use the towel wiping method. This can lead to fabric residues on the products, water in the recesses of the relief, and damage to the decorative part. You can use sawdust for this purpose.

Methods using chemical reagents

One of the most common methods is the use of liver sulfur. It can be purchased at the store or prepared at home. To do this, mix powdered sulfur with potassium chloride in a ratio of 1:2 and put it on fire in a tin can. After a few minutes, the powder will melt and, after 15 minutes, will sinter, its color becoming dark brown. This process may be accompanied by a flame, which does not need to be put down.

The first method, which uses liver sulfur to blacken copper, is as follows: 10–20 grams of powder are dissolved in one liter of water, or two to three grams if it is necessary to obtain a less intense color. The copper product is dipped into the solution until the color changes, then it is removed, washed and dried. The color turns out to be brown-gray and its shades.

The almost black color of the product is obtained by heating, after treatment in a solution of liver sulfur with water and the addition of ammonia. Alcohol must be added to the saturated solution until it turns transparent blue. A coin or copper jewelry is dipped into the solution and then heated until it turns black.

Another method for obtaining black-brown color is as follows. Platinum chloride is applied to the product, for example, wetted with a brush. If the solution is not acidic, hydrochloric acid is added to it.

A red-brown patina can be obtained using a one-to-one mixture of copper sulfate and zinc chloride. The mixture of powders will need to be mixed in the same amount of water and the copper product should be immersed there for a few minutes.

Patination of copper with ammonium sulfide produces a black color. The substance (20 g) is diluted in a liter of water. You can either dip the product into the solution or apply it with a brush. A reaction occurs on the surface, resulting in the formation of copper sulfide. If you heat the plate before patination, then depending on the temperature, you can adjust the shade of the resulting color.

Blackened copper product

Another way to obtain black color is to heat a coin or jewelry at a high temperature in a solution of ammonium persulfate (9.25 g/l) and caustic soda (50 g/l). The temperature should be 90–95 degrees, the warming time should be 5–25 minutes. Repeat two to three times until the desired effect is achieved.

A light brown patina can be obtained by covering the product with the following solution:

• 124 g/l sodium dichromate;
• 15.5 g/l nitric acid (1.4);
• 4.65 g/l hydrochloric acid (1.192);
• 3–5 g/l 18% ammonium sulfide solution.

Apply the newly prepared solution with a brush, leave for four to five hours, rinse and dry. The procedure must be repeated three times.

Green patina is obtained by two main methods:

• Using a sponge, the copper surface is lubricated with a low concentration solution of copper nitrate with the addition of table salt. After drying, lubricate it with a solution containing: 94% table vinegar, 5% ammonia, 1% potassium oxalate. After drying, lubricate first with the first and then with the second solution again. The procedure is carried out until the copper reaches the desired color. After painting is completed, the surface is rubbed with brushes.
• In the second method, the surface of the copper product is rubbed several times with oleic acid. This produces a dark green substance on the surface - oleic copper. Over time, the shade changes to light green, as under the influence of moisture and oxygen, oleic copper is converted into carbon dioxide. A solution of five grams of potassium permanganate and 50 grams of copper sulfate gives a golden-brown patina. Dilute in one liter of water and heat to a temperature of 70–80 degrees. Lower the product and hold until the desired color is obtained.

To obtain a highly wear-resistant coating that protects the metal from corrosion, take in grams per liter of water: 50–70 berthollet salt, 40–50 copper nitrate, 80–100 ammonium chloride. The product is placed in a bath with a heated solution for 10–15 minutes. The color ranges from brown to olive.

You can get an amazingly beautiful golden patina. To do this, take 0.6 grams of copper sulfide, 180 g of milk sugar and the same amount of sodium hydroxide per liter of water. Aqueous solutions of the last two components are prepared separately and only then mixed. Copper sulfide is added only after the mixture has boiled. Place the product in a solution heated to 90 degrees for a quarter of an hour.

Getting patina with an egg

A black-brown patina can be achieved using a boiled egg. The effect is the interaction of the metal surface with sulfur, which is released in the yolk at high temperatures. To do this, you must first boil the eggs, and only then add the copper product to the water. Depending on the size of the product, a different number of eggs will be required.

Another option. After the eggs are hard-boiled (10 minutes), they must be removed from the water and cooled. The peeled eggs are crushed and placed in a container with a wide bottom, and copper is also placed there.

The container is closed for 20-30 minutes or more, depending on what color you want to get: over a longer time, the product will become darker. The main advantages of this method are simplicity and accessibility.

The main disadvantage is that the effect most likely will not be long-term and the coating will come off.

Patina has excellent properties. For example, in numismatics, the value of an item depends on how uniform it is. Artificial turf cannot replace natural turf.

If the patina has a uniform structure and evenly covers the surface, then it is better to preserve it on the product. This especially applies to antiques and coins. To prevent damage to the top layer, it is necessary to care for the product and handle it with special care. Do not clean with abrasive products or tools. And it’s better not to touch the product with your hands.

But if it has chips, stains, looks ugly or is not uniform, then such methods will do just fine. If you want the patina to lay down evenly, then the old layer must be cleaned to a metallic shine.

Source: https://DedPodaril.com/lityo/chernenie-medi-v-domashnih-usloviyah.html

How to protect copper from oxidation? — Machine tools, welding, metalworking

Corrosion of copper is not as well known as the corrosive effects of iron. However, the mechanisms of influence on the metal structure are similar. This is spontaneous destruction when exposed to various types of aggressive environments. It is impossible to unequivocally compare the concept of rust with copper corrosion.

Corrosion of any metal is associated with thermodynamic instability under the influence of active elements that are in the air. The rate of copper corrosion will directly depend on temperature fluctuations. If you increase it by 100 degrees, the pace increases 2-3 times.

Next, we will consider how corrosion of copper alloys occurs and how to protect them from oxidation in various deployment environments.

Corrosive properties

Due to the lack of chemical activity in copper, upon contact with water or humid air, its corrosion practically does not occur. When exposed to dry air, the metal can form a small oxide film up to 50 nm thick. If the product is tinned, then almost no film is formed.

A high-quality tin coating can reliably protect against moisture and temperature changes. Moreover, the service life of such an item can be up to 100 years without loss of original properties. The color will not change over time. The use of tinned surfaces has long shown its best performance.

An example would be the domes of many temples.

Due to the high threshold of corrosion resistance, copper is actively used in many chemical and electrochemical industries. For example, the process of copper plating helps solve many processing problems. In one of the previous articles, we looked at the procedure at home, we recommend that you read it.

Water influence

Corrosion of copper in water and the speed of the process will depend on the presence of an oxide film and the volume of oxygen dissolved in it. As a rule, an impact or point process occurs. In this case, the speed will be faster, the greater the amount of oxygen contained in the water. A liquid containing chlorine ions and a low pH level will also have a negative effect.

In general, the surface’s resistance to corrosive influences is quite high, which is facilitated by the presence of an oxide film, which does not allow the destructive element to penetrate into the metal structure. An oxide layer will form when the metal remains in water for more than 2 months. Oxide coating can be of two types:

• · Carbonate – green in color. It is considered to be the most durable.
• · Sulfate – dark in color. It has a loose structure and less strength.

The metal is often used in the production of various pipelines. However, if the liquid flowing through them comes into contact with aluminum, zinc, or iron, then it significantly accelerates their corrosion. To prevent this and protect copper from corrosion, tin plating is again carried out.

Effect of acid and alkali

Corrosion of copper in acidic environments is less detected. The effect of nitric and sulfuric acid will be the strongest. If you place it in a concentrate of these acids, it can completely dissolve. These features are taken into account when choosing alloys for elements and pipelines in the oil and gas industry.

In an alkaline environment, the effect is not observed at all, since alkali allows copper to be reduced from a 2-valent to a 1-valent state. It is worth remembering that it itself is an alkali metal.

Protection against oxidation and corrosion under the influence of acids is carried out by inhibitors - substances that slow down the chemical reaction. The following types can be distinguished:

• · Shielding – form protective lashes and exclude the possibility of contact with acids.
• · Oxidative – the formation of an oxide occurs, which reacts with acids, thereby preventing their penetration into the metal structure.
• · Cathode – designed to increase the overvoltage of the cathodes of the solution, due to which chemical reactions reduce their intensity.

As a rule, corrosion of copper in acidic environments is prevented by shielding type inhibitors. The most common is benzotriazole, which, together with copper salt formations, forms a protective shell, slowing down the rate of corrosion or almost completely stopping it.

Exposure to soil and moist air

Corrosion of copper in the soil is mainly caused by the influence of acids contained in the soil. Compared with the effects of water, oxygen in the soil oxidizes metal elements much less. The most dangerous microorganisms in the soil are, or rather, their secretions. They are often capable of releasing hydrogen sulfide, which destroys metal. Thus, copper lying in the soil for a long time can completely decompose.

In humid air the process does not proceed rapidly. It takes a long time. In a dry climate, destructive effects may not be observed at all. This is explained by the fact that in humid air there is a high concentration of carbon dioxide, sulfides, chlorides, which cause corrosion and are destructive to the protective film.

Prolonged exposure to humid air can cause the formation of a patina layer. This is the name given to green deposits on copper. It consists of salt oxides, which are initially dark brown in color, and then the surface begins to turn green.

The peculiarity of patina is that it cannot be dissolved in water and is not affected by high air humidity. It has neutral properties to copper itself, which allows it to protect the surface from the harmful effects of the environment.

In addition, modern methods of creating artificial patina make it possible to use it in objects of art and during restoration.

Look at your personal experience in combating corrosion with the help of inhibitors.

Source: https://stanki-info.com/kak-zaschitit-med-ot-okisleniya/

Difference Between Copper Oxychloride and Copper Sulfate

The main difference between Copper Oxychloride and Copper Sulfate is that Copper Oxychloride is an inorganic copper compound and is used as a fungicide and bactericide, whereas Copper Sulfate is an inorganic copper compound and is used as a fungicide and herbicide.

Copper oxychloride and copper sulfate are copper-containing compounds that are used primarily as fungicides. The chemical formula of Copper Oxychloride is Cu2(OH)3Cl and the chemical formula of Copper Sulfate is CuSO4.

1. Overview and main differences
2. What is Copper Oxychloride
3. What is Copper Sulphate
4. What is the difference between Copper Oxychloride and Copper Sulfate
5. Conclusion

What is Copper Oxychloride?

Copper oxychloride is an inorganic compound with the chemical formula Cu2(OH)3Cl. The chemical name of this compound is copper(II) hydroxide-chloride. It exists as a green crystalline solid.

This substance is found in mineral deposits, metal corrosion products, archaeological sites, etc. This compound is produced on an industrial scale for use as a fungicide. Its molar mass is 213.56 g/mol.

 The melting point of this compound is 250 °C and it is insoluble in water and organic solvents.

Copper oxychloride

Copper oxychloride occurs naturally in four different polymorphic structures: Atakamite, Paratacamite, Clinoatacamite, and Botalaklit. These different polymorphs have different crystal structures:

• Atacamite - rhombic
• Paratacamite - rhombohedral
• Clinoatacamite - monoclinic
• Botallakite - monoclinic

At temperatures above 220 °C, copper oxychloride decomposes. During this process, the acid HCl is decomposed. In a neutral environment this compound is very stable. But, in an alkaline environment at high temperatures, this compound decomposes, yielding copper oxides.

What is Copper Sulphate?

Copper sulfate is an inorganic compound with the chemical formula CuSO4. This compound is found primarily in hydrated forms. Here, the number of water molecules associated with copper sulfate can range from 0 to 5. Moreover, the pentahydrate form of this compound is the most common. The anhydrous form appears as a white powder, but the hydrated form is bright blue.

Copper Sulphate Crystal

Copper sulfate is produced on an industrial scale by treating copper with sulfuric acid. Here the sulfuric acid is in hot and concentrated form. In addition, copper sulfate can be made using copper oxides, for which the copper oxide is treated with dilute sulfuric acid. Also, this compound is produced by slowly leaching low-grade copper ore in the air. Bacteria are used to catalyze this process.

Dehydrated copper sulfate appears as a gray-white powder. The molar mass of copper sulfate is 159.6 g/mol. The density is 3.60 g/cm3. The melting point of copper sulfate is 110 °C; upon further heating, the compound decomposes.

What is the difference between copper oxychloride and copper sulfate?

Copper oxychloride is an inorganic compound having the chemical formula Cu2(OH)3Cl, while copper sulfate is an inorganic compound having the chemical formula CuSO4. Copper oxychloride is used as a fungicide and bactericide, while copper sulfate is used as a fungicide and herbicide.

Additionally, another difference between Copper Oxychloride and Copper Sulfate is that Copper Oxychloride appears as a green crystalline solid, while Copper Sulfate appears as either a white crystalline powder (anhydrous) or usually as bright blue crystals (in pentahydrate form).

Copper oxychloride is an inorganic compound having the chemical formula Cu2(OH)3Cl, while copper sulfate is an inorganic compound having the chemical formula CuSO4.

 The key difference between Copper Oxychloride and Copper Sulfate is that Copper Oxychloride appears as a green crystalline solid, while Copper Sulfate appears as either a white crystalline powder (anhydrous) or usually as bright blue crystals (in the pentahydrate form ).

Source: https://raznisa.ru/raznica-mezhdu-oksihloridom-medi-i-sulfatom-medi/

How to oxidize copper at home - Metals, equipment, instructions

Copper was one of the first metals mastered by man back in prehistoric times. Weapons and tools, household utensils and jewelry were made from copper.

And all these millennia, people have been faced with the question: how to clean copper products from the stains that inevitably appear on them.

How to clean copper

Why copper products need to be cleaned regularly

During use and storage, copper products become covered with a dark or green coating. The oxide film is formed as a result of the interaction of the metal with atmospheric oxygen.

Heating or using the item outdoors or in rooms with high humidity accelerates plaque formation. At the same time, dishes and decorations lose their appearance and look untidy.

In the sailing fleet, most of the metal parts of the ship were made of copper, and there was even such an expression as “scrubbing a piece of copper.”

In addition, the chemical compounds that make up plaque can have harmful effects on human health. Therefore, copper products must be cleaned regularly.

Copper oxidation

Since ancient times, people have been improving cleaning methods, using both mechanical and chemical methods.

Effective cleaning methods

Today, the arsenal of tools that can be used to clean copper has expanded significantly. Together with ancient vinegar, sand and wire sponges, a large number of both specially designed products and those adapted by folk craftsmen are used. Among the latter there are some quite unexpected ones.

 How to clean copper

• Tomato ketchup. Apply a small amount of tasty seasoning to the stain and leave for several minutes. Rinse off with plenty of water.
• In case of light stains, you can try washing them with a regular gel detergent. The gel is squeezed onto a soft sponge and then applied to a copper object. After leaving for a minute, rub the surface and rinse with water.
• Used for large products, such as a samovar. Cut the lemon in half and rub the half over the surface of the product. Next, clean with an elastic fluffy brush and rinse with water.
• Vinegar dough. Mix vinegar and regular table flour in equal parts. Stir until a homogeneous paste-like mass is obtained. Next, the paste is spread in a thin layer on the surface to be cleaned. After waiting for complete drying, remove the product with a rag or wooden spatula. The product must then be polished with a soft cloth.

If the above methods do not lead to success, use the following method:

• Prepare a stainless steel basin or pan.
• Pour vinegar and add a couple of tablespoons of regular table salt. Stir thoroughly.
• Immerse the item to be cleaned in the solution and bring to a boil.
• Remove from heat and leave to cool at room temperature.
• Drain the cooled solution, rinse the copper object and wipe dry.

Cleaning copper with vinegar

If you decide to clean copper, take precautions. The use of protective gloves and glasses is mandatory. If you dilute vinegar essence, you should ensure ventilation of the room.

Copper utensils and jewelry should be cleaned regularly. With regular care, copper cleaning is carried out by regular washing or wiping with kitchen or sanitary gel. If plaque covers a significant area and cannot be removed by simple means, more radical cleaning methods are used.

How else can you clean copper?

• Citric acid powder is diluted at the rate of a tablespoon of acid per liter of water. Add a teaspoon of table salt and stir thoroughly. Use the resulting solution to wipe away plaque stains using a sponge or cloth. The method is convenient for items that do not fit in the sink: large figurines, door and window fittings, samovars, teapots, etc.
• Black deposits should be cleaned with ammonia. If you have to clean dishes, be sure to thoroughly rinse the utensils with plenty of water. If ammonia enters the human body, it can lead to serious poisoning. In the case when individual stains merge into a continuous layer of plaque, it is better to soak the entire product for one to three minutes.
• It is better to clean red stains with an ammonia solution with a strength of no higher than 10%. Carefully! Ammonia is poisonous. Be sure to provide adequate ventilation.
• It is good to clean yellow and black stains with a mixture based on regular 9% vinegar. To one part vinegar, take one part salt and two parts water. Immerse the item to be cleaned in the tank with the solution and bring the mixture to a boil. Carefully monitor the disappearance of stains - as soon as they have dissolved, stop boiling and allow the tank to cool. Next, the product should be rinsed with plenty of water and wiped dry.

Before you begin cleaning the entire copper item from oxides, you should test the effect of the cleaning composition in an inconspicuous place or in a small area.

If the product is effective and does not damage the surface, you can clean the entire product.

How to make copper products shine

If you simply clean copper, the stains will go away, but the item itself will not shine. A dull surface can be made shiny using one of the following methods:

• Mechanical polishing with newspaper or printed leaflet printed with black ink only. Rub the surface until the shine is restored.
• Wiping with a weak solution of hydrochloric acid. Precautions must be taken: the room must be well ventilated, and the use of protective gloves and goggles or a transparent face shield is mandatory.
• Mix equal parts vinegar, table flour and regular salt. Stir until it becomes a thick paste. Apply the paste to the cloth and polish the surface until shiny. At the end of the operation, rinse the item with warm water.

Polished copper

To restore the shine to copper products, you should regularly care for them. Then it will be possible to do without the use of strong chemicals that are hazardous to health.

Causes of plaque on copper

As copper products are used or stored, their shine gradually fades, and they begin to become covered with plaque - oxide films. They have a variety of shades - from dark green to light blue.

There are several main causes of plaque:

• Due to contact with oxygen in the air, the copper surface becomes covered with a layer of green patina.
• Copper jewelry darkens when it comes into contact with skin and sweat secretions. If the copper darkens very quickly, it may indicate a health problem
• Plaque also occurs when there is high humidity or direct contact with water.

Craftsmen often deliberately patina their products, giving them a more antique appearance. This is the so-called “noble patina”

Cleaning copper from white deposits

The white coating is also an oxide film. It most often occurs on the surface of copper alloys. Its color is determined by the metals that make up the alloy. This oxide layer can be cleaned using the following methods:

• when the content of other elements in the part material is low, sulfamic acid is used. This potent chemical should be used with great care, limiting the time and area of ​​exposure. Careful adherence to safety precautions is mandatory.
• A mixture of two tablespoons of salt per glass of whey is made. The resulting composition is rubbed onto the surface using a soft cloth. After you have finished cleaning, you must thoroughly rinse and dry the product.
• You can also clean white deposits with regular ketchup. A little seasoning is applied to the item, the acidic environment of ketchup restores its original appearance and shine. After cleaning, rinse with plenty of water and wipe dry.
• A thick layer of white plaque should be cleaned by boiling in a mixture of table salt and 9% edible vinegar. The item is boiled until the plaque dissolves, cooled slowly and washed with plenty of cold water.
• Another way to clean white plaque is a mixture of ammonia and powdered chalk. The resulting thick paste after mixing should be applied to the object and rubbed with a stiff brush. At the end of the process, wash and dry the surface.

To properly clean copper objects, you have to spend a lot of time and effort, but brightly shiny products will be pleasing to the eye.

How to clean copper from black and green deposits

If you need to clean copper from green and black deposits, use the following methods:

• Moisten the cloth with a mixture of oxalic acid, turpentine and ethanol and wipe the object several times. Ethanol degreases the surface, acid dissolves the oxide layer.
• A mixture of powdered chalk and kerosene is made. Lump chalk should be pre-crushed. This product can not only clean, but also polish copper objects.
• Warm soapy water (or other non-abrasive detergent). The product is completely immersed in the solution and wiped with a thick sponge.
• To clean copper products, you can also use a special composition for cleaning copper coins and medals Trilon B.

  Connection of copper and aluminum wire rules

Cleaning with ammonia

Important: Black and green deposits are harmful to health; kitchen utensils covered with them cannot be used for preparing and preserving food.

Cleaning copper from rust

When copper objects come into contact with iron objects, in addition to patina, rust may appear on them - flaky iron oxides.

Rust can be cleaned with strong acid solutions. The sequence of operations is as follows:

• Prepare two containers of the same size made of ceramic, glass or stainless steel.
• Wear personal protective equipment: goggles or a clear face shield, gloves and a respirator.
• Pour an aqueous soda solution into one container.
• Pour the acid solution into the other.
• Slowly and carefully, using tweezers or pliers, completely submerge the copper object.
• During the reaction, dark smoke will appear.
• After cleaning the copper object, it should be removed from the container with the acid and immersed in another with a solution of soda for quenching.
• Rinse and dry the item being cleaned.

Removing rust with cola

In addition to chemical reagents, Coca Cola drink can also be used to clean copper products. It contains orthophosphoric acid. (A good reason to think about whether you should drink such a drink)

Precautions when cleaning copper

To preserve the health of people and material assets, you must strictly follow the safety rules:

• When working with chemically active substances, be sure to ensure ventilation of the room.
• Clothing and shoes should be tight and not leave any exposed skin.
• The use of protective gloves and glasses (face shield) is mandatory.
• Do not lean over containers with reagents, especially if a violent reaction occurs with the release of gaseous products and splashing.
• To avoid scratching the surface, do not clean copper products with hard wire brushes or rough abrasives.
• There is no need to keep objects in acidic solutions longer than necessary - in addition to the oxide layer, it is also possible to dissolve the product itself.
• Valuable figurines, coins and decorative items should be cleaned only with mild products. It would be a good idea to consult with experienced specialists.

Timely and regular care will allow you to maintain a beautiful appearance, true color and radiant shine for many years.

, please select a piece of text and press Ctrl+Enter.

Source: https://spb-metalloobrabotka.com/kak-okislit-med-v-domashnih-usloviyah/

How to oxidize copper at home

Over time, copper items lose their color and begin to take on a dark or green tint.

This happens naturally during the process of oxidation, but modern designers actively promote vintage interior elements; it looks beautiful, sophisticated, and expensive.

Antique copper bowl

But to achieve a beautiful shade of patina, you don’t have to wait several years; you can age the product artificially. There are many ways to do this. You can choose any one that suits you best.

Basic Tools

The use of various aging methods involves the use of some tools or improvised means. But there are universal items that are used with any method:

Patination is the artificial aging of copper interior items

• the product itself, carefully processed;
• thick rubber gloves;
• safety glasses for eye safety;
• aging agent (vinegar, ammonia, prepared solutions, acetone, ammonia);
• soap or just water for cleaning;
• magnet for checking the composition;
• hot treatment (hair dryer or any other heating agent);
• brush;
• special container (bucket, tin cans, plastic jars);
• means for polishing and grinding (sponge, cloth).

Using ammonia

Before starting work, you need to process the copper item with a file (a special file for jewelry work) - such preparation helps to clean the item from dirt and put it in order. To treat with ammonia you will need: the treatment agent itself, any container with a tight-fitting lid, a cotton pad and a lid the size of it.

Table of brands of copper products of a famous antique brand

The cotton pad should be placed in a small lid, thoroughly soaked in ammonia and placed together with the copper product in an airtight container.

After 10 minutes you can see how the copper item has aged.

When opening the container, do not forget that you can smell a strong smell of alcohol, so it is better to use a protective bandage.

Using Vinegar

In order to age a copper item with vinegar, you need to carefully prepare it. The preparation process consists of several stages:

You can age copper in vinegar

• If the copper product is covered with a layer of varnish, then it must be removed. To do this, you need to either hold the product in a container with acetone, or carefully treat it with a brush with the same product;
• Next, the copper item needs to be poured with hot water and rinsed so that the varnish comes off completely;
• if the copper item does not have any additional coating, then it will be enough to simply wash it with soap;
• The aging process cannot be started if the product is not dry enough. To speed up drying, you can use a hair dryer, but before doing this, make sure that there are no traces of protective coating left on the copper, otherwise the copper product may catch fire.

After the preparatory stage is completed, you can begin processing with vinegar. The big advantage of this method is that you do not need to work with harmful substances and you always have vinegar on hand in the kitchen.

As with acetone, you can either dip the item in vinegar or apply it to a brush and thoroughly treat the item.

Also, if you need to get a green patina, you can add a spoonful of salt to the vinegar.

After the desired result is achieved, the copper item should be rinsed in warm water and gently dried with a towel.

Aging with a gray tint using sulfur liver

First you need to prepare sulfur liver. This can be done as follows:

Liver sulfur (sodium polysulfide)

• mix sulfur powder and potash in a 1:1 ratio in a tin jar, put the mixture on fire;
• after the mixture begins to melt and darken, the sintering process begins;
• After 15 minutes, remove the tin from the heat and let the mixture cool slightly.

Now you can begin preparing the solution in order to begin patination and age the copper item. Mix 3 g of salt and 3 g of cooled sulfur liver in 1 liter of water.

Mix the solution thoroughly and dip the copper product into it. When the copper has acquired the required gray tint, you can remove the product, then rinse with water and dry.

Using a ready-made aging solution

This method is the fastest, since the product itself does not need to be prepared independently; it is sold ready-made.

Since the aging solution contains substances that are harmful to the skin, do not forget to wear gloves and safety glasses.

Brass Black Metal Finish for aging copper, manufactured by the American company Birchwood Casey

Different solutions may have different information about the quantities in which the liquid should be diluted, but you should always follow the instructions that are indicated on the label of the purchased product.

When the preparatory processes are completed, you can begin to process the copper product.

To do this, you need to lower the copper item into the solution several times at different angles so that the entire surface of the item is covered with the product.

It is necessary to ensure that there are no bubbles, since then light spots may remain in their place.

You should repeat this procedure until you get the desired color.

Overexposure or, conversely, raising the product from the solution too early is not a problem, since during overexposure you can treat it with a scraper, and if the desired color is not achieved, lower it into the product again. At the end of the process, the copper must be dried and varnished if the achieved result is to be secured.

Use of ammonia

Of all the products presented, ammonia is the most caustic substance, but it can age copper best of all and gives a brownish-green patina.

The disadvantage of using this product is that this gas evaporates, which is why it needs to be treated more often than with other substances.

To use this method you will need: ammonia itself without impurities, a sealed plastic bucket, small wooden blocks.

Patination or aging of copper coins

The ammonia application method consists of the following steps:

• Place the bars at the bottom of the bucket so that you get a small but stable platform;
• pour ammonia into the bucket without bringing its level to the upper surface of the platform;
• place the copper product on the wooden structure so that it holds firmly on the platform. If it falls from it, then you just need to take it out, rinse it with water and place it again on the bars;
• Close the bucket tightly and check readiness every hour. The procedure usually takes several hours. While checking the appearance of the desired shade, do not inhale ammonia vapor.

Drying, as with other methods, is a mandatory and final stage of aging. You can dry it naturally, without using a hair dryer or other hot methods.

It is not worth covering the product with varnish, since you will have to periodically remove it, because, as mentioned above, treatment with ammonia is carried out many times during the use of the copper item.

Application of ammonium sulphide

Copper must be placed in ammonium sulfur solution

In order to age copper, you can use the substance ammonium sulfide, mixing which with other substances can give the product a patina of different shades:

Set for aging copper surfaces from Idigo

• light brown - 5 g of ammonium sulfide solution 18%, 124 g of sodium dichromate, 15 g of nitrogen acid with a density of 1 g per 1 cm3, 5 g of hydrochloric acid are mixed in one liter of water. The mixture is applied to the product with a brush, washed off after 5 hours, and after drying, repeat this procedure 2 more times;
• dark brown - 9 g of ammonium persulfate and 50 g of sodium hydroxide are mixed in one liter of water. The solution is heated to 95 degrees. The product is immersed in the solution for 5-25 minutes, depending on the desired color saturation, washed and dried. The procedure is repeated 3 times.

The use of various other substances that help age the item and give a patina of different shades:

• golden - 1 g of copper sulfide, 180 g of caustic soda and 180 g of milk sugar are mixed in one liter of water. The solution must be heated for 15 minutes to 90 degrees. After which the product is lowered into it for 15 minutes, and then dried.
• golden brown with a raspberry sheen - 50 g of copper sulfate and 5 g of potassium permanganate are mixed in one liter of water. The mixture is heated to 80 degrees, and the product is kept in it until the desired result is obtained.

Useful tips

If you are not an expert in chemistry, then it is better for you to use ready-made means for aging copper or the simplest methods (using vinegar, for example). It will be more difficult for the average person to grasp the need for certain proportions and not make a mistake in creating the desired solution.

https://www.youtube.com/watch?v=s2-0hGlxXgw

Golden patina on a copper coin

If you have experience in working with chemicals, you can try using the prepared solutions first on individual parts of the copper product, so as not to re-patina every time the result is unsuccessful.

Solutions containing any hypochlorite should be avoided, since this substance is very difficult to control at home and its careless use will have the most dangerous impact on health.

When using any method, you need to remember your protection: long gloves and safety glasses must be worn.

If you have doubts about whether a product is copper or not, you need to take it to an antique shop. A specialist will quickly be able to determine what metal the item is made of.

You can also check the composition of the product by holding a magnet to it. If an item sticks to a magnet, then most likely it is not copper, but just a copper coating applied to the metal.

  How to polish copper

In this case, it is also possible to age the product, while eliminating rough processing.

: Patination of copper at home

Source: https://steelfactoryrus.com/kak-okislit-med-v-domashnih-usloviyah/

How copper corrosion occurs in water, alkali, and acid. Protection measures

Corrosion of copper is not as well known as the corrosive effects of iron. However, the mechanisms of influence on the metal structure are similar. This is spontaneous destruction when exposed to various types of aggressive environments. It is impossible to unequivocally compare the concept of rust with copper corrosion.

Corrosion of any metal is associated with thermodynamic instability under the influence of active elements that are in the air. The rate of copper corrosion will directly depend on temperature fluctuations. If you increase it by 100 degrees, the pace increases 2-3 times.

Next, we will consider how corrosion of copper alloys occurs and how to protect them from oxidation in various deployment environments.

Copper corrosion: causes of rusting and methods of protection

Copper products have been used by humans for several centuries. In pre-revolutionary times, the price of this metal was equal to the cost of gold, its production was so expensive. Now copper has become much cheaper, so in addition to jewelry, it is used to make dishes, interior accessories and other items.

Corrosion of copper, unlike iron, develops slowly due to its resistance to this phenomenon, and yet sometimes it is necessary to take measures to clean products from unsightly plaque.

Corrosion refers to the process of destruction of metal under the influence of aggressive environmental factors. To one degree or another, all metals and alloys rust, as a result of which rust and areas of integrity damage (holes) appear on them. Non-metals can also deteriorate over time: an example is the aging of rubber or plastic from interaction with oxygen, frequent contact with water, and temperature changes.

The main cause of corrosion is considered to be the thermodynamic instability of the metal to the influence of physical factors or chemical substances that are present in the contact medium. Compared to iron, copper oxidizes much less, but with increasing temperature this process accelerates significantly. When regularly exposed to an environment with temperatures above +100 degrees, any metal rusts several times faster.

Corrosive properties of copper

Copper is a metal with high plastic properties, having a red-golden color, and after removing the oxide film - slightly pinkish. In terms of electrical conductivity, it is second only to silver, and is also characterized by high thermal conductivity. Due to its low resistivity, copper is used in electrical engineering: it is used to make copper plates, wires, and motor windings.

Due to its high anti-corrosion qualities, the metal is included in alloys to improve their technical characteristics (bronze, brass and others). In a galvanic environment, copper becomes a cathode, enters into electrochemical processes and causes accelerated rusting of other metals.

Copper is an inactive chemical element, therefore it practically does not interact with air or water (fresh, sea). If the air is dry, an oxide film up to 50 million thick is formed on the surface of the material.

The copper product darkens, becomes brown or greenish, this is called patina. In some cases, patina is perceived as a decorative coating.

The intensity of corrosion is low upon contact with dilute hydrochloric acid, but when reacting with a number of other acids, with halogens, and “regia vodka,” the metal is oxidized to form copper carbonate.

Material failure conditions

Despite their resistance to damage, even copper products can rust under certain conditions. Such phenomena are least expressed in humid air, water, soil, and more pronounced in an acidic environment.

Corrosion can be seriously reduced by tinning - coating copper with a layer of tin. High-quality tinning provides reliable protection from damage, increases corrosion resistance, and makes the material not susceptible to high temperatures, rain, hail, and snow. The service life of tinned products is more than 100 years without loss of original properties.

Exposure to acids and alkalis

Copper does not deteriorate in alkalis, because the material itself is alkaline, but acids are the most harmful in terms of their effects. The most significant and rapid corrosion occurs upon contact with sulfur and its acidic compounds, and nitric acid completely destroys the structure of the material.

Copper dissolves in concentrated acids, so it requires additional protection when manufacturing equipment for the oil and gas industry. For this purpose, inhibitors are used to slow down chemical reactions:

1. Shielding – form a film that prevents acids from reaching the copper surface.
2. Oxidizing - convert the top layer into an oxide, which will react with acids without harm to the metal itself.
3. Cathode - increase the overvoltage of the cathodes, thereby slowing down the reaction.

Corrosion in soil and moist air

The soil contains many microorganisms that produce hydrogen sulfide, so the environment here is acidic, and the rate of copper corrosion increases. The more the pH value deviates towards acidification, the faster the destruction processes occur.

If the soil is saturated with oxygen, the metal oxidizes, but rusts less. When copper products are left in the ground for a long time, they turn green, become loose and may even crumble.

Brief exposure to soil causes a patina that can be removed from the item.

Humid air has a bad effect on the condition of the material only with prolonged contact, and initially also causes the appearance of a patina (oxide layer). The exception is steam saturated with chlorides, sulfides, carbon dioxide - corrosion develops more rapidly in it.

Effective Copper Cleaning Methods

Cleaning copper items is easy and does not require expensive products. Here are the most popular techniques used at home:

1. Ketchup. Take a little tomato ketchup, lubricate the product with it, and leave for two minutes. Then rinse with running water.
2. Dishwashing solution. Lather a household sponge with regular dish soap, wipe the surface thoroughly, and rinse with water. This method is best for items that are only slightly faded.
3. Lemon. Rub the copper surface with a slice of lemon, then go over it with a stiff bristled brush and wash with water.
4. Vinegar and flour. Pour a little vinegar into a cup, add flour until you get a medium-thick dough. Lubricate the copper with the dough, leave until dry, then remove the residue and rub the product with a soft cloth.
5. Vinegar and salt. Pour 9% vinegar into a stainless steel pan, add a little salt, and let it boil. Turn off the heat, put a copper object into the solution, do not remove it until the liquid cools. This method is suitable for heavily soiled surfaces.

Cleaning Copper Coins

Copper coins are antiques and are not issued in modern times. They often have to be cleaned to restore their attractive appearance. If the coin has been in contact with lead, the coating may be yellowish. In this case, it can be easily cleaned with table vinegar (9%). Green plaque is removed with a solution of citric acid (10%) or lemon juice, brown plaque is removed with ammonia or ammonium carbonate.

It must be remembered that sometimes a layer of patina gives coins a more noble and vintage look, so it is not always advisable to remove it. Some, on the contrary, try to artificially age money at home.

To do this, you need to take a liter of distilled water, 5 g of pharmaceutical potassium permanganate, 50 g of copper sulfate. Heat the solution without boiling, throw coins into it, and leave until the desired shade is achieved. To consolidate the effect, treat dried money with a mixture of benzene and alcohol (1:1).

Afterwards, the coins will acquire a beautiful aged appearance and will be able to decorate any collection of antiques.

Source: https://kraska.guru/specmaterialy/korroziya/rzhavchina-na-medi.html