This compound can be used for cold blackening of copper and copper alloy parts.
The coating has good corrosion resistance and can be used as a final finish. If the part is additionally oiled, the corrosion resistance can be increased and a deeper, more saturated black color can be obtained.
This coating is not suitable as an undercoat for painting.
Surface preparation.
Despite the fact that this coating is matte, it is recommended to polish the surface of the part. If the surface contains oxides, grease stains, deep traces of corrosion, etc., it is necessary to carry out mechanical processing (grinding or sandblasting).
Before applying the coating, the surface must be cleaned of grease, residues of polishing pastes, greases and oxides.
For this, the part after mechanical preparation must be processed in stages with intermediate rinsing in solutions. "UNIVERSAL CLEANER" and "ACTIVATOR".(See Surface Preparation Instruction). During the surface preparation processes, it is necessary to carry out high-quality washing of parts. In case of poor-quality washing, the part after preparation may become covered with an oxide film, on which the coating is deposited extremely poorly.
Blackening copper
After surface preparation, you can proceed directly to the blackening of copper. This process is chemical and does not require the use of a current source and anodes. To carry out the process, the part is simply dipped into the blackening solution and kept there for a certain time. To avoid uncovered areas on the part (due to the formation of bubbles), it is necessary to periodically swing the suspension with the part fixed to it.
Process parameters
After rinsing, the parts are immersed in the fixing solution and kept there for the required time. During this process, it is also recommended to periodically wiggle the suspension with the part. Before carrying out the curing process, using a hydrometer, measure the density of the solution. If necessary, adding a fixing reagent to it, bring its density to a value of at least 1.1 g / ml.
The parts do not need to be rinsed after the fixing solution.
Process parameters
After the fixing solution, the part is dried. After drying, the surface of the part is oiled (by dipping or wiping) in a low-viscosity industrial oil heated to a temperature of 35-40 ° C. Higher corrosion resistance of the oxide film can be obtained by oiling the part in hot linseed oil.
Copper is a low activity metal and for this reason is often used for decorative purposes. Copper is used to make jewelry, home furnishings, art, furniture and much more. The surface of the metal is oxidized by oxygen, but due to its low activity, this may take tens of years. 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 the copper at home.
There are two types of reactions that lead to the formation of films on the copper surface:
Oxidation is a process of formation of oxides and nitrous oxide, elements containing oxygen;
patination - the film is formed by the action of sulfur and chlorine.
If you dip a copper product in a solution designed to form a patina on its surface, it will immediately transform and, being sparkling new, will look like an old one. There are two main types of methods that achieve this effect, 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 rules. 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 the fact that there will be remnants of fabric on the products, water in the recesses of the relief, damage to the decorative part. Sawdust can be used for this purpose.
Methods using chemical reagents
One of the most common methods is using sulfuric liver. It can be purchased at the store or prepared at home. To do this, mix powdered sulfur with potassium chloride in a 1: 2 ratio and put on fire in a tin can. After a few minutes, the powder will melt and, after 15 minutes, it will bake, its color will become dark brown. This process can be accompanied by a flame, which does not need to be brought down.
The first method, in which sulfuric liver is used for blackening copper, is as follows: 10–20 grams of powder is dissolved in one liter of water, or two to three grams, if it is necessary to obtain a not intense color. The copper product is dipped into the solution until the color changes, then taken out, washed and dried. The color turns out to be brown-gray and its shades.
Almost black color of the product is obtained by heating, after processing in a solution of sulfuric liver with water and the addition of ammonia. Alcohol must be added to the saturated solution until it turns clear blue. A coin or copper jewelry is dipped into the solution, and then heats up until it turns black.
Another method of obtaining black-brown color is as follows. Platinum chloride is applied to the product, for example, moistened with a brush. If the solution does not have an acidic reaction, hydrochloric acid is added to it.
A reddish-brown patina can be obtained with 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 lowered there for a few minutes.
Patination of copper with ammonium sulphide gives 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 patinating, then depending on the temperature, you can adjust the shade of the resulting color.
Another way to obtain a black color is to heat a coin or decoration 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 warm-up 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 coating 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 of 18% ammonium sulfide solution.
Apply the freshly prepared solution with a brush, hold 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 solution of copper nitrate in a low concentration with the addition of sodium chloride. After drying, it is smeared with a solution containing: 94% table vinegar, 5% ammonia, 1% potassium oxalate. After drying, they are lubricated first with the first, and then with the second solution again. The procedure is carried out until the copper acquires the desired color. At the end of staining, the surface is rubbed with brushes.
In the second method, the surface of the copper product is rubbed several times with oleic acid. This gives a dark green substance on the surface - oleic copper. Over time, the shade changes to a light green, since under the influence of moisture and oxygen, oleic copper is converted into carbon dioxide. A golden brown patina gives a solution of five grams of potassium permanganate and 50 grams of copper sulfate. Dilute in one liter of water and heat to 70-80 degrees. Lower the product and hold until the desired color is obtained.
To obtain a coating with high wear resistance, which protects the metal from corrosion, per liter of water take in grams: 50–70 Berthollet's 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 amazingly beautiful golden patina. For this, 0.6 grams of copper sulfide, 180 g of milk sugar and the same amount of caustic soda are taken 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 is boiled. The product is placed in a solution heated to 90 degrees for a quarter of an hour.
Getting a patina with an egg
A black-brown patina can be obtained with a boiled egg. The effect lies in 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 a copper product to the water. Depending on the size of the product, you will need a different number of eggs.
Another option. After the eggs are hard-boiled (10 minutes), they must be removed from the water and cooled. Peeled eggs are crushed and placed in a container with a wide bottom, and copper is also placed there. The container closes for 20-30 minutes or more, depending on what color you want to achieve: over a longer time, the product will darken. The main advantages of this method are simplicity and affordability. The main disadvantage is that the effect is unlikely to be long-term and the coating will wear off.
Patina has excellent properties. For example, in numismatics, the cost of a product depends on how uniform it is. Artificial turf will not replace natural.
If the patina has a uniform structure and evenly covers the surface, then it is better to preserve it on the product. This is especially true for antiques and coins. To prevent damage to the top layer, it is necessary to take care of the product and handle it with particular care. Do not clean with abrasive products or tools. And it is better not to touch the product with your hands.
But if it has chips, spots, looks ugly or heterogeneous, then such methods will do quite well. If you want the patina to lie flat, then the old layer must be cleaned to a metallic sheen.
The surface of an aluminum object is first polished with the finest emery powder.
Then it is smeared with olive oil, and heated with frequent greasing with this oil, over an alcohol lamp, until the olive oil turns black.
After that, the heating is stopped and after the object has cooled, the oil is wiped off with a rag.
Black mordant for iron and steel:
The bluing of iron and steel, which has its purpose, on the one hand, to give the surface of these metals a beautiful appearance, and on the other to protect them from rust, consists in the fact that metal surfaces, carefully polished and cleaned from grease and dirt, are rubbed with various mixtures from appropriately selected substances and then exposed to high temperatures.
Here are some practical and fast-acting bluing compounds;
1. 1 part of silver nitrate (lapis), 500 parts of water;
2. 1 part of antimony chloride, 1 part of olive oil;
3. 2 parts of antimony chloride, 2 parts of ferric chloride (crystalline), 1 part of ink-nutty acid;
4. 54 parts of copper sulfate, 3 parts of iron filings, 14 parts of nitric acid, 26 parts of alcohol, 200 parts of water.
Black mordant for copper:
A saturated solution of copper sulfate is prepared and ammonia is added to it until the mixture takes on a bright transparent blue color. The thing to be treated is dipped in this solution for a few minutes, then removed and heated slightly until it turns black.
Another method is that a copper thing to be blackened is first cleaned with fine sandpaper, after which they try not to touch it with their hands to its cleaned surface.
Then it is either immersed in a liquid solution of platinum chloride, or moistened with it with a brush. This solution, if it does not have an acidic reaction, is slightly oxidized with hydrochloric acid.
Very strong blackening of copper products is obtained if they are immersed in a saturated solution of metallic copper in nitric acid and then slightly heated.
Black mordant for bronze:
Usually, both pure black and gray coloration is obtained by the formation of copper oxide or copper sulfide on the surface of the thing. But both of these staining can be achieved by the deposition on the surface of things of sulfur compounds of other metals - lead, bismuth, mercury and others. Will the staining be completely black or light black, i.e. gray, depends both on the composition causing the color and on the time of action of the latter.
For the formation of black copper oxide on the surface of things, the heated thing is immersed for a few seconds in a solution of copper in an excess of nitric acid, and then held over the fire of charcoal until its surface begins to turn black.
To obtain a uniform and sufficiently thick black color, the operation is repeated several times, otherwise the color will not be completely black, but grayish. At the end of staining, wipe the thing with a cloth moistened with oil. Optical instruments are usually blackened in this way.
For brass and bronze, you can use the following solution: 2 parts of arsenic (not arsenous) acid, 4 parts of hydrochloric acid, 1 part of sulfuric acid and 80 parts of water. Arsenic acid can be replaced with antimony oil (antimony trichloride). The thing is immersed in a solution heated to 50 degrees Celsius, and during the immersion they touch it with a zinc stick.
Very good staining is obtained by a solution of a double salt of sodium sulfate and lead:
Dissolve 45 g of lead sugar (lead acetate) in 3/4 liter of water, and 150 g of sodium sulfate (hyposulfite) in 1/2 liter of water. Mix both solutions and heat to 85-93 degrees. The surface of a thing immersed in a solution very quickly becomes covered with a layer of lead sulphide. The color of this layer changes as it thickens and finally becomes a very beautiful metallic gray.
Black mordant for silver:
Blackening is a widespread and almost the only method used in practice for coloring the surface of silver or silvered things, and not the entire surface of the thing is painted black, but only some of its parts in the form of various shapes, patterns, etc. This kind of adornment of silver items with niello has been known for a long time.
The blackening process consists in the formation or deposition of silver sulfide on the surface of a silver thing. By handicraft, blackening is done chemically; the deep patterns engraved on the surface of the thing are filled with a fusible compound including sulphurous silver, then the thing is exposed to a high temperature sufficient to fuse the composition with the silver.
In short, there is a partial coating of the surface of the thing with "black enamel", the composition of which is different.
Here is one of the good recipes for such black enamel: 38 parts of silver, 72 parts of copper, 50 parts of lead, 384 parts of sulfur and 36 parts of borax are melted in a crucible, and the metals that make up the composition turn into sulfur. Upon cooling, the alloy is crushed into a fine powder and carefully sieved.
When used, the engraved areas are sprinkled with enamel powder and the item is kept on fire until the enamel melted again fills the recesses.
Upon cooling, the excess enamel is erased, the thing is grinded and polished. Sometimes silver or silvered things (vases, figures) are accented with graphite. To do this, they are lubricated with a kashtice-like mixture of 6 parts of graphite in powder and bloodstone in powder with turpentine (bloodstone or crocus is native iron oxide).
When the grease dries, the thing is wiped off with a soft brush and suede, then its convex places, to give them a greater shine, are polished with a cloth moistened with alcohol or vodka.
Such an emphasis is purely mechanical and is caused by the same conditions that, over time, produce pollution of any metal surface; adhesion of dust particles to irregularities and roughness of the surface.
Consequently, the less smooth the surface, the more successfully it can be accentuated by this mechanical method. Such blackening is not as strong as chemical blackening.
Read also:
Copper is a low-activity metal that is often used for decorative purposes. The article discusses the main methods for changing the color of copper at home and in the laboratory.
General information about metal color
OXIDIZING copper and brass
Copper is often used as a decorative element on buildings, including furniture, jewelry, and art objects. The metal surface enters into a chemical reaction when it comes into contact with oxygen, however, it takes several decades to complete it.
The fruit of the interaction of copper and air is patina - the same material, only with a greenish tint. Less common is a black or brown patina. Practice has shown that the color of the patina can be corrected if it is treated with special means or methods.
Processing methods
Blackening copper with boiled eggs
Under the influence of high temperature, chemical reactions occur in the yolk with the release of sulfur. The interaction of our metal with sulfur gives it a dark brown color. In order for the chemical reaction to proceed correctly, the actions must be performed exactly with the instructions: first, eggs are boiled, then a copper product is added. The number of eggs depends on the size of the copper product. They are boiled for exactly 10 minutes, after which they are removed and cooled.
Chilled chicken testicles are cleaned and finely kneaded by any means at hand. Next, you need a small container with a lid and a wide bottom. Place the copper piece and crushed testicles in a container. Make sure that both ingredients do not touch, otherwise colored spots will appear on the metal product and blackening will end in failure.
The combined ingredients are closed for 20-30 minutes in a container. It is worth noting that the result of the experiment depends on the duration of their stay together - the longer both ingredients stay in a confined space, the darker the metal you get.
Advantages of the method: to darken the metal requires few resources: a couple of chicken eggs, an old iron container and a gas stove. Disadvantages of the method: short-term and unstable effect. The results achieved may be lost over time or when exposed to reaction with a more aggressive chemical.
Discoloration of copper by potassium sulfide
This darkening method is considered one of the best for darkening copper. Sulfide is a very active substance that must be used carefully at home. If it gets into the respiratory tract, it can cause unpleasant symptoms of nausea, dizziness, etc.
The metal must be prepared - wash it in warm water and soap. Otherwise, dust residues and greasy stains will interfere with the normal passage of the chemical reaction.
Further, a reagent is prepared - sulfide. It is sold in three flavors: liquid, gel, and solid. The shelf life of the reagent varies depending on its state of aggregation. For example, liquid sulfide is stored for no more than 2 weeks, while solid sulfide is stored for several decades. Please check the date of manufacture before purchasing.
To carry out the reaction, you will need an empty container where solid sulfide is diluted or where liquid is poured. Dilute the reagent with water only (it can be cold or hot, there is not much difference). Be careful not to let its vapors enter the respiratory tract.
The entire procedure is best done outdoors or in a well-ventilated area. When it comes to hand protection, it is best to wear protective rubber or latex gloves on your hands to prevent contact of the corrosive substance on the skin. For extra protection, wear normal goggles over your eyes.
If for any reason sulphide gets on the skin, then the affected area must be rinsed abundantly with running water. The same is done if it gets in your eyes. If the reagent penetrates inside, it is necessary to provoke vomiting and immediately consult a doctor.
Depending on the type of substance, it must be prepared in different ways:
- Liquid and gel sulfide is diluted according to the instructions on the label;
- Solid first crumbles to a powdery state, after which it is mixed with water until it is completely dissolved.
A cold or slightly warm solution is needed to darken the copper. Before throwing the metal into the solution, you need to prepare a solution of water with soda in a ratio of 1:16. Soda neutralizes the action of an aggressive substance and will instantly stop its action.
The copper salt changes color.
Put a copper piece or product in a container and watch the reaction carefully. Remove the product only with metal tongs. Once the blackening reaches the desired consistency, remove it from the sulfide solution and place it in baking soda to stop the reaction.
If blackening is too slow, then the container can be slightly warmed up, this will speed it up. For even more acceleration, you can add 5 milliliters of ammonia. It is worth noting that the presence of ammonia gives copper a reddish tint rather than black.
If the copper is too dark, it can be lightened with a regular detergent powder. Apply a little powder to the hard surface of a washcloth and scrub well. Then the product is washed in warm water.
Homemade solution
This method produces green or brown copper. To prepare the mixture, you will need: ammonia solution, baking soda, water, and an empty container. Before proceeding with the color change, the part must be prepared - washed in warm water and wiped dry.
When working with ammonia, it is necessary to observe safety measures: carry out experiments only in a well-ventilated room, wear gloves on your hands and protect your eyes from harmful vapors and splashes.
To obtain green copper, blackening must be carried out with: an empty container where 0.5 l is poured. vinegar, 125 ml of iodized salt and 375 ml of ammonia (pure). The required ingredients can be purchased at the store and pharmacy. The amount of salt added affects color saturation. Dip the copper into the prepared mixture for a few seconds and watch the reaction carefully. As soon as you are satisfied with blackening, remove the item and rinse with water.
Copper can also be made brown. For these purposes, you will need baking soda, water, and a bottle. Soda must be added to the bottle until it stops dissolving. Place a metal object in a container and fill it with the prepared mixture. It is highly discouraged to use sprays and other methods of applying soda solution to copper. This will give the copper object an uneven coloration.
The damp object is wrapped in a plastic bag and left in this form for 1-8 hours, depending on what contrast you want to get the color.
Thus, you can change the color of copper at home. To do this, you will need a metal container with a lid, water, copper product, baking soda, vinegar, and ammonia. Most of the ingredients listed are sold at the grocery store and pharmacy. When conducting experiments, do not forget about safety - use goggles and rubber gloves.
Video: Copper History
The easiest way to blacken copper is with ammonia vapor (ammonia). A denser color is obtained if the product (the wire is pre-soaked in a solution of sodium chloride for several hours).
Internet survey showed. that this is not the only method. Most of the information I found on the forum with ship modelers: http://shipmodeling.ru/
Bringing the scale of copper products closer to ship modelers and striving for a good and lasting effect. I chose those recipes that forum participants give as proven in practice and for which, in principle, you can find materials:
1. Buy in a store for jewelers or in a store for hunters special compositions for blackening (bluing) metal. (Not cheap!)
2. Prepare black mordant for copper: Dissolve copper sulfate in warm water. The solution needs to be saturated, i.e. add vitriol until it dissolves. Add ammonia until the mixture turns a bright transparent blue color. The workpiece to be processed must be immersed in the solution for several minutes, removed and heated until the part turns black.
3. Spread with sulfuric ointment and put in a warm place (on the battery) for several hours. True, they say that the coating is not very durable.
4. Prepare a simplified version of the sulfuric liver solution, in which potash is replaced with soda ash. Here's a more detailed description of the process: " A ceramic bowl with a handle, like a pot. In 150 ml of distilled water, I dissolved two tablespoons of soda ash (bought in a household chemicals store in a package similar to washing powder), brought it to a boil and began to add colloidal sulfur (bought at a flower fertilizer store) also two or three tablespoons. The yellowish solution began to darken and after 7-8 minutes it acquired a brown color. Either I did not calculate with grams in a spoon, or the water boiled away, but in my opinion the required liquid was not enough and I added more water to the eye and boiled it more. The final liquid turned out to be a slightly yellowish-greenish tint. At the bottom there is a thick layer of yellowish sediment. Gently poured the resulting liquid.
My cannons are made of copper-plated lead. Commercial products did not give a stable coating, and this cloudy liquid gave my copper products a radical black color within 1 minute. The staining is stable, unlike my store-bought ready-made reagents, and even. It lends itself to polishing with a brush, but becomes dark dark gray and begins to shine. "
5. And, finally, one more recipe (though there is only a link on the forum, no one has used it): Dissolve 4 g of caustic soda (caustic soda) and 4 g of milk sugar in 100 g of water, boil for 15 minutes, then, with constant stirring, add in small doses 4 g of a saturated solution of copper sulfate. Well-cleaned copper products are immersed in the hot mixture. Depending on the duration of the action, they will acquire different colors - from gold, green to complete blackness.
Milk sugar is a baby food product. Here is a link to the manufacturer (among the distributors there are store addresses in Russia). http://oltri.ru/page102.html
6. And this is just a recipe from the vastness of the Internet: Very strong blackening of copper products is obtained if they are immersed in a saturated solution of metallic copper in nitric acid and then slightly heated.
In my previous post # 378, where sulfuric liver is used for patination / oxidation, there is one point: despite the fact that copper darkens quickly and intensely during processing, there is a suspicion (my knowledge of chemistry is not so deep for 100% judgment) that the composition of the dark coating is only partly contains copper oxide (and does it contain at all ?!), and perhaps most of the component belongs to CuS, because the reagent contains sulfur. I do not presume to judge on this score and I will be glad to hear the opinion of an experienced chemist (ayyyy). Accordingly, the selectivity of this coating created by the sulfuric liver is questionable and is waiting for its inquisitive researcher. By the way, sulfuric liver is elementary to make at home: sulfur and ordinary baking soda are baked over low heat, there is a lot of information on this in the internet, seekers will find.
And for all those who are suffering and have patiently read this topic up to this point, I want to share (however, there are almost no fans of this issue) the latest personal discoveries that make obtaining an oxide film on copper sooo simple and safe, as well as a way to quickly and easily and safely remove this film completely, returning the copper to its original pinkish tint.
1) similar to the industrial method of blackening copper with caustic soda NaOH + NaClO2 with all the risks of working with this caustic compound, and even heated (powerful evaporation is guaranteed), it was decided to try ordinary baking soda and nothing more! .. And lo and behold - everything worked out! What is the essence of the idea: it is profitable in industry to use NaOH as a widespread very active and inexpensive reagent, the use of such an alkali as baking soda will cost several times more and such nonsense can only come to mind for a household maniac rationalizer, and NaOH also allows the process to be produced enough fast, 15-30 minutes, and in industry time is money. That is why links to blackening copper with baking soda were not found on the Internet (how many of these enthusiasts who want to blacken copper at home using improvised methods to obtain selective oxides! Oh, madmen!) But! At home, splurging on baking soda is more convenient and safer.
And the next important point: unlike caustic soda, the process in soda proceeds very slowly (another reason why this topic is unknown is you put copper in soda and almost nothing happens, even after a couple of hours, it seems that it does not work) but is it really a problem ? personally, I was in no hurry! In general, 2 teaspoons of soda for about 100 g of water gives a saturated solution, in which we put the copper product and leave ... After a day we come and see a noticeable darkening to a brown-brown hue (as expected), and after the second day the copper part becomes almost black with a slight purple tint! I didn't keep it for the third day, the photo shows exactly a 2-day exposure. Everything is as it should be! And let someone say that this is not an oxide! In addition to alkali (as well as with caustic soda), nothing was used, the color sequence of darkening completely repeats the description of industrial oxidation: pure copper - brown tint - brown - black - black with purple. In addition to simplicity, accessibility and safety, this household method of oxidizing copper with baking soda has a very interesting and important advantage over the industrial method of blackening with caustic soda: the formation of an oxide film in a soda solution is very slow, which means it is very easy to obtain the desired color intensity and uniformity of film application! To overexpose or overheat / underheat the solution, do not observe the proportions as in the industry - you have to be completely burdock, the shade scale - plus or minus 1-2 hours of exposure. It is enough to stir the solution 3-4 times a day (stir, shake) to achieve a uniform color of the entire surface. I got a very pretty detail evenly painted in black with a purple tint.
2) the discovery of N2 is even worse (of course, for smart people this is not a discovery, but nothing of the kind was found on the internet) and was done by "typing" or "what if", in general, to destroy the film on copper by turning it into pure pink copper even faster and easier, using the same baking soda (teaspoon) + table salt (teaspoon), about 100 g of water: put copper in this mixture, stir and after a few seconds the copper is like new!
I place a photo of a copper tube oxidized for 2 days in a saturated solution of soda and a washed tube in a mixture of soda + salt.
If these ideas help someone to make an efficient solar collector that is not much inferior to industrial counterparts, save a lot of money and cut Gazprom's bills for heating or heating in half, then I did not run this branch in vain ..
I hope these questions are of interest to someone else.
It does not belong to precious metals, but has long been used for the manufacture of banknotes and decorative elements. People have noticed the ability of the material to change its color under the influence of time, taking on different shades (from green to black). The oxidation process, accompanied by a darkening of the surface, can be accelerated - this is the blackening of copper. There are several ways to artificially induce patina (plaque) on the surface of non-ferrous metal, giving it the look of patriarchy and antiquity.
Purpose of patination
The main purpose of using copper darkening is to impart an aging effect to the metal being treated. In ancient times, most items (coins, figurines, various souvenirs, household items) were made from this material. Having reached our time, objects have undergone some transformations - oxidative processes have changed the color and general appearance of these things, creating all the signs of antiquity and, therefore, value.
Nowadays, copper patination is made artificially, but at the same time they pursue a single goal - to give things a rarity, to draw attention to themselves, to arouse the desire to acquire it.
Preparing for patina
As with any work with chemicals, safety is the first priority. Most of the formulations used in blackening are highly toxic. Vapors released into the atmosphere can be hazardous to health. There are certain standard rules that cannot be ignored:
- you need to store substances in special test tubes, tightly closed with corks for sealing;
- keep solutions out of the reach of children;
- the process should take place in a specialized cabinet with built-in ventilation (cabinet doors should be slightly open).
Before starting processing, the material should be thoroughly washed, cleaned and degreased to achieve the best effect.
Oxidation and patination- these concepts are not synonymous, the consequences of each of these processes differ in order from each other.
Copper oxidation- the formation of oxides and oxides on the surface of the metal due to its interaction with oxygen-containing elements and other certain chemical reagents.
Patination- the formation of a thin layer of chlorine and sulfur compounds by acting on the metal with appropriate compounds. Both processes lead to a change in the color of the material, which would take significant periods of time under natural conditions.
Patination at home
There are several of the most common and universal methods for blackening copper. The use of these methods allows using chemistry to achieve the desired result in the shortest possible time. The most popular among them are:
- using boiled eggs;
- exposure to potassium sulfide or sulfate;
- applying copper sulfide solution;
- placing in a solution of copper sulfate with zinc chloride or potassium permanganate.
Obvious visual differences between material exposed to time and nature, or treated with a special solution, are negligible, and in some cases are completely absent. Therefore, artificial patination is a rather effective technique.
Boiled eggs
The easiest way that does not require special chemicals. All actions to achieve the expected result must be performed exactly, following the instructions:
- boil eggs (at a high temperature, chemical processes occur in the yolk, accompanied by excretion);
- remove and cool after 10 minutes of cooking;
- after cooling, peel and crush into small pieces;
- place the eggs with the prepared object in a container, cover with a lid (copper should not come into contact with the eggs, but just lie next to it);
- Leave the ingredients in the container for 30 minutes or more (the longer the metal is inside, the darker it will become).
As a result, from the interaction of copper with sulfur released by a boiled egg, the product should change color, taking on a dark brown hue. The number of eggs used in the experiment depends on the dimensions of the copper object (the larger the object, the more eggs). The method of blackening copper with a boiled egg has two significant drawbacks: fragility and instability. Over time, the result is lost. The advantage is the simplicity and accessibility of the experiment itself.
Potassium sulphide
One of the best ways to darken metal is with potassium sulfide. Before starting the experiment, the product should be thoroughly washed and degreased so that the copper patina is correct and gives a good result.
The required reagent for the reaction is sold in three aggregate forms: solid, gel and liquid. Each species has a different shelf life: liquid - up to two weeks, solid - several years.
For work, you will again need a container in which the sulfide will be diluted. The reagent has a high level of toxicity, so you should take precautions - be sure to wear gloves and glasses. The procedure itself is recommended to be carried out outdoors or in a room with a good ventilation system.
A chemical element is diluted only with water (hot or cold), based on the state of aggregation. The solution is diluted according to the instructions attached to the purchase. The solid reagent should first be ground into powder, and then mixed with water until dissolved.
After completing all preparations, you can place the copper object in the solution and observe the process of the chemical reaction. First, it is necessary to prepare the composition of water with soda (1:16) to stop the action of an aggressive substance. At the end of the process, carefully remove the product from the solution with tongs and place it in prepared water with soda to stop the reaction. The copper patination process is over.
Potassium sulfate is produced during the oxidation of sulfide at high temperatures. Its effect on a copper product is faster. The effect is similar.
Use of copper sulfide
This chemical is produced by the reaction of bivalent copper salts with sulfur. The resulting copper sulfide compound is capable of causing a discoloration of the copper. Moreover, the quality of the shade depends on the saturation of the solution with sulfur.
The black substance used is insoluble in water and dilute acid formulations, so the resulting shading is durable and resistant to abrasion or washout.
The termination of the blackening process, as in the previous method, occurs after placing the product in water with soda dissolved in it. If the resulting color is too dark, it can be lightened by rubbing with a cleaning powder. Then the copper object is washed with water and dried.
Patination with copper sulfate solution
You can achieve the appearance of a brown film with a red tint on the product. The preparation of the solution is prepared as follows:
- water is poured into a glass container;
- powder of copper sulfate is diluted in it;
- zinc chloride is added and everything is mixed.
The ratio of ingredients: 50% - water, 25% - copper sulfate, 25% - zinc chloride.
Depending on the time the item is in the resulting compound, its color can change from red to brown.
The formation of a white-green coating on copper occurs by immersing the metal in a composition obtained by adding potassium permanganate (5 grams per 1 liter) to a five percent aqueous solution of copper sulfate.
Artificial copper color
In addition to the described methods, there are other methods of patination and oxidation of copper, which make it possible to impart the following colors and shades to the material:
- brown-gray - when immersed in a sulfuric liver solution;
- dark gray - when the product is heated in a combination of a solution of sulfuric liver and ammonia;
- brown-black - occurs under the action of platinum chloride (if the result is not satisfactory, you can add hydrochloric acid);
- black - as a result of exposure to sulfuric ammonium, diluted in water;
- green - from the application of low concentration copper nitrate mixed with table salt, or from oleic acid;
- golden - from being placed in a heated solution of copper sulfide, caustic soda and milk sugar.
The use of each method gives its own result and differs not only in the color of the patina, but also in the duration of the preservation of the coating. Sometimes, to protect the product, it is coated with varnish, then blackening does not disappear from time to time.
Scunc 10-02-2015 14:14
All health and success!
Please share the experience of who inked copper, I used the search, but I want to ask who did it personally.
Is it a stable (not rubbed by hands) black color and how?
Desirable from available materials ...
Max_CM 10-02-2015 14:19
You can erase anything.
take the copper in your hands, start up hot water from the tap, and rub the copper with ointment under the stream.
sansem80 10-02-2015 14:22
quote: Originally written by Max_CM:
... hot water from the tap, and rub the ointment with ointment under the stream.
Oh how. And then I applied this ointment to dry and cold copper, nothing really blackened.
And the ointment is not washed off under the stream? How to rub it? With a rag?
vladimir c 10-02-2015 14:30
I tried to rub it just with my finger on cold finely dispersed sulfur (sold in gardening stores) - it got blackened.
Vitaly B 10-02-2015 14:36
Quote: Originally posted by Max_CM:
In the nearest pharmacy, sulfuric ointment 3kop price.
I did it differently, I spread a layer and put it on the hot case of a table lamp, or blow it with hot air with a hairdryer and everything turns black not badly in 3-5 minutes, though I did it on silver, the copper should darken faster. after acetone or with soap, wash everything ...
------------
Best regards, Vitaly.
www.vitaliknife.ru
Scunc 10-02-2015 14:37
Here I am and ink with sulfur ointment, it is good to blacken, but the ink is easily erased completely, I wonder about the jet, what does it give?
Max_CM 10-02-2015 14:44
He just heats it up, it's more convenient for me, straight with his fingers, Vitaly puts it on the lamp, no matter how important it is to heat it.
Viziter 10-02-2015 14:45
Sodium thiosulfate (from the pharmacy, ampoules of 10 ml, inexpensive) + any acid (I did it with acetic acid). Pour in thiosulfate, add acids until the color of milk and the smell of hydrogen sulfide is obtained, lower the copper (bronze, brass, etc.). The color, depending on the shutter speed, is quite fast.
They told me well about sulfuric ointment, I smeared it on a cold one, it did not help.
niks78 10-02-2015 15:07
when I stained an oak in ammonia, I laid down the copper tire, it turned black with a blue overflow. persistence did not check
vityuxa 10-02-2015 15:43
quote: here is an excellent blackening tool.RUB 1,470.0 for 90 ml. Six or even seven vodka funfires! The question is about resilience, is it worth it? how about erasability? I tried. But it is imperative to take Potash (POTASSIUM carbonate) exactly, with food (SODIUM carbonate) soda, the effect is not the same, it is less stable, and the coating is once at a time. Not bad yet; Smear the cleaned, fat-free part with a brush with nitric acid, ambergris is not comme il faut, but not particularly, in the common fund at the station. And immediately heat it up, the color can be very varied, but there is a knack for inflating. And with acid and sulfuric liver, the coating is erased only with fine sandpaper or polished paste. I will subscribe to every word, since I myself was bothering with this inky idea.
Nestor74 10-02-2015 15:53
quote: http://www.medwed-hunt.ru/Good...atalogBegin- there is an excellent blackening tool here.
Really
Look in the BrassBlack gun stores - I haven't seen anything better yet. The effect is instant. Blacks copper, brass, bronze, silver. What other sulfuric ointment? One must keep pace with the times. On all my works, patination is done with this liquid.
Trident8 10-02-2015 16:00
Sulfuric liver: sulfur (took in a vetaptek) mixed with baking soda 1: 1, calcined stirring until brown, diluted slightly with water - and in business, cheap and cheerful.
niks78 10-02-2015 16:39
and when I stained the oak with our oak, I laid down the copper bus, it turned black
Androniy 10-02-2015 16:53
I wanted to darken the copper coin only slightly, but with the slightest application of sulfuric ointment, a dark brown coating was immediately obtained. I found a solution - add a little sulfuric ointment to a large amount of petroleum jelly. Then he applied it to the fabric and rubbed it vigorously. The result is a light brown patina.
Max_CM 10-02-2015 17:03
quote: Originally written by vityuxa:
RUB 1,470.0 for 90 ml. Six or even seven vodka funfires! The question is about resilience, is it worth it? how about erasability? I tried. But it is imperative to take Potash (POTASSIUM carbonate) precisely, with food (SODIUM carbonate) soda, the effect is not the same, it is less stable, and the coating is once at a time. Not bad yet; Smear the cleaned, fat-free part with a brush with nitric acid, ambergris is not comme il faut, but not particularly, in the common fund at the station. And immediately heat it up, the color can be very diverse, but there is a knack for inflating. And with acid and sulfuric liver, the coating is erased only with fine sandpaper or polished paste. I will subscribe to every word, since I myself was bothering with this inky idea.
www.chip-dip.ru sera fick knows him, ran through all the pharmacies, it turns out there is only where the potions themselves are prepared in production,
begged for a teaspoon, run home and quickly cook!
A stainless steel ladle came under my hands, and blackening still remains on it! STICK! I thought the neighbors would call the Emergencies Ministry right now!
Blacks cool, I don't remember resistance to copper, but it is easily erased from silver, and unfortunately, this brew is not stored, it decomposes, each time it has to be boiled again. In!
hunter1957 10-02-2015 18:51
quote: Aha! about two or three years ago I got confused with a sulfur liver, potash in www.chip-dip.ru knows it, I ran through all the pharmacies, it turns out there is only where the mixtures themselves are prepared in production, begged for a teaspoon, ran home and quickly cook! stainless steel ladle, so blackening still remains on it! STICK! I thought the neighbors would call the Ministry of Emergency Situations right now! It's cool, I don't remember the stability on copper, but it is easily erased from silver, and unfortunately, this brew is not stored, it decomposes, every time it has to be cooked again. In!In Ruskhim, it will take chemistry on a more budgetary basis .......
Scunc 10-02-2015 20:45
And this liver is stored, if for future use?
vityuxa 10-02-2015 21:29
quote: every time you have to cook again. In!The solution is in the refrigerator for a month, the secret is simple, right under the neck, just try with a "slide" so that it spills out from under the cork when swirling, it works fine, though when the cold is slower. The cooked powder will lie as quickly as you like, without moisture, in my vial from under the vitamins I also threw small bags of silica gel for medicines there. And there are some nuances, first melt the sulfur, well, it stinks, of course, the main thing is not to dry out, it's not scary, but the stench is bigger, and only then slowly pour potash and stir it. I made 1 sulfur 1.5 potash. A good correct powder came out only 4 times, then the sulfur does not dissolve, then some kind of shitty, lumps. Well, zayo # in the head, you have to do it, you can't stop ...
i_vb 10-02-2015 22:16
I do not make knives in large quantities, but I do a lot, with copper elements - even less often. I'm using the aforementioned BrassBlack. For cupronickel, the same is suitable. A bottle costs 700 rubles, not 1600, at least in Moscow. I don't know how long it will last, but 3 years, about 20 different parts - a third of the bottle. These things cannot be removed with a scabbard and hands, with a zero - it is easy, however, like the vaunted liver.
PySy: If there is a cat in the house - throw a copper or brass bolster in his toilet for a day, I guarantee old bronze. Moreover, even with zero, you can't immediately remove it. But - slightly divorced. Checked.
vityuxa 10-02-2015 23:00
Here are the chemists: they are certainly impartial. http://chem21.info/info/18373/ In colors from gray-black to black-brown, you can paint products from copper and its alloys by oxidation in solutions of ammonium sulfide or sulfuric liver. The so-called sulfuric liver is a mixture of various potassium polysulfides with potassium thiosulfate. Sulfuric liver is obtained by fusion of sulfur with potash for 15-20 minutes. In various recommendations, it is proposed to alloy 1 hour (wt.) Sulfur with 1-2 hours (wt.) Potash (potassium carbonate K2CO3). Sulfur is melted in a porcelain cup, then dry potash is gradually added to the melt with constant stirring. When air enters, interaction between the components of the melt occurs and a brown viscous mass is formed
If, when preparing sulfuric liver, instead of potash, it is fused with sulfuric soda (sodium carbonate), then light gray captivity will form on the surface of silver treated with such a preparation.
Scunc 11-02-2015 06:57
As I understand it, ordinary sulfur, i.e. yellow pieces?
RashchektaI 11-02-2015 08:26
Well, why bake something? When there is ready-made pure thiosulfate.
Scunc 11-02-2015 11:35
Quote: Originally written by RashchektaI:
Well, why bake something? When there is ready-made pure thiosulfate.
Add acid to it and that's it? Just do not write which and how much (
I have nitrogen 60 and acetic 70, okay?
Scunc 11-02-2015 12:42
Interestingly, have you tried it?
Nestor74 11-02-2015 13:01
quote: Interestingly, have you tried it?
quote: Works almost throughout the "polish" tested
I was not too lazy to count. I treated 100 knives with this liquid, did not use half of them (!!!) 100
How else can you convince?
If you just smear it with a solution of thiosulfate, it doesn't blacken. just barely ... it's not a job. Only frustration.
vityuxa 11-02-2015 13:25
quote: Vityukha is clear, it is more important for him to buy vodka, he squeezes))Not Sanya, I'm not greedy, I'm ideologically piz # anuty, and I don't believe in anything until I do it myself, or I won't do it, but I will do it until I succeed ... ...
Scunc 11-02-2015 17:06
BrasBlack is interesting, just at first it stopped the price and availability, then looked ... there is sulfur at work in bags, thiosulfate is sold in the pharmacy, i.e. some hemorrhoids anyway. You can't just buy in the store (
But I selected three main options for myself, so I will move in this direction, which one will be available from that and I'll start)
And thanks for the advice! I needed personal opinions.
LE 11-02-2015 18:04
quote: Originally posted by i_vb:
The bottle costs 700r
Please tell me where did you get it in Moscow?
GM63 11-02-2015 19:50
I still do not understand about BrasBlack. Religion does not allow? Where else with goodness?
No stench, no acid, no need to add ... He unscrewed the cork, dipped a brush, anointed, twisted ... No dancing with a tambourine ...
Vityukha is clear, it is more important for him to buy vodka, he squeezes))At least that much will be enough.
How else can you convince?About thiosulfate. It works in hot water with the addition of hydrochloric acid. It is needed as a catalyst. It won't work with acetic acid. I checked already)))
The product must be immersed in a hot solution for a few minutes. Those. this option is not convenient for us. A knife that is ready to be put there, but you can blacken the part separately, but then you will rip it off during installation, scratch it ...
Alexander.
Somehow you misunderstood me, apparently
Scunc 11-02-2015 21:17
Sodium thiosulfate-prescription drug (
Scunc 11-02-2015 21:24
Quote: Originally written by GM63:
Alexander.
Even I did not understand. On the contrary, I say that I am against this collective farm with sulfur acids and a stench in the kitchen.
But for just buying a special Noirit slurry in "Noirit" at 400 rubles per 100 ml. and use it, tk. it blackens and ages almost any color of meth, and brass-copper generally in a black wing.
True, when ordering, you need to remind them to check the packaging. Last time I ordered, half of it came out.
Somehow you misunderstood me, apparently
i_vb 12-02-2015 12:24
quote: Please tell me where did you get it in Moscow?
I wrote that I took it a long time ago - two years ago. For 560r.
Last time I saw it in a hunting store on Kalanchevka for 750r. before New Year.
If I don’t forget, I’ll come and take a look.
And so - in hunting stores. The idea with a cat was ignored in vain - it works for free!
GM63 12-02-2015 01:00
Quote: Originally written by Scunc:I'm looking for (BIRCHWOOD CASEY 15225 BB2 Brass Black Metal Touch-Up) that's how it is called correctly.
And what is there to look for ...
Any gun shop has.
RashchektaI 12-02-2015 08:31
Quote: Originally written by Nestor74:I still do not understand about BrasBlack. Religion does not allow? Where else with goodness?
No stench, no acid, no need to add ... He unscrewed the cork, dipped a brush, anointed, twisted ... No dancing with a tambourine ...
Vityukha is clear, it is more important for him to buy vodka, he squeezes))
I was not too lazy to count. I treated 100 knives with this liquid, didn’t use half of them [b] (!!!) 100At least that much will be enough.
How else can you convince?About thiosulfate. It works in hot water with the addition of hydrochloric acid. It is needed as a catalyst. It won't work with acetic acid. I checked already)))
The product must be immersed in a hot solution for a few minutes. Those. this option is not convenient for us. A knife that is ready to be put there, but you can blacken the part separately, but then you will rip it off during installation, scratch it ...If you just smear it with a solution of thiosulfate, it doesn't blacken. just barely ... it's not a job. Only frustration.
What an apologist for Brasbleck you are. When you need to make a hundred knives and the cost of one pours for 30 r, it’s easier to buy, but when you make one knife a year with copper, it’s doubtful. At the expense of acid - I tried it badly, and even with vinegar essence it works with a bang. BUT nitrogen or sulfuric acid is preferred.
111StS111 12-02-2015 10:04
I blacken Raven with bluing agent 3. Blacks steel, cupronickel, copper, bronze, brass. I have not tried stainless steel. Doesn't take silver. The coating is quite durable.
It costs 200 rubles.