Copper is an inactive 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
OXIDATION OF COPPER AND BRASS
Copper is often used as decorative element on buildings, including in the manufacture of furniture, jewelry, art objects. The surface of the metal 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 influence high temperature occur in the yolk chemical reactions with sulfur release. 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 according to the instructions: eggs are boiled first, then a copper product is added. The number of eggs depends on the size of the copper product. They cook 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 will need a small container with a lid and a wide bottom. Place the copper item and crushed testicles in a container. Be careful that both ingredients do not touch, otherwise colored spots will appear on the metal product and the 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: few resources are required to darken the metal: a couple of chicken eggs, an old iron container and gas stove. Disadvantages of the method: short-term and unstable effect. Achieved results may be lost over time or when reacting with a more aggressive chemical.
Changing the color of copper with potassium sulfide
This darkening method is considered one of the best ways to darken copper. Sulfide is a very active substance that must be used carefully at home. If it enters 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 spots will interfere normal passage chemical reaction.
Next, a reagent is prepared - sulfide. It is sold in three forms: 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. 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 sulfide is poured. Dilute the reagent only with water (you can use cold or hot, there is not much difference). Be careful not to inhale its vapors.
The whole procedure is best done outdoors or in a well-ventilated area. As for the protection of the hands, it is better to wear protective gloves made of rubber or latex on the hands to prevent the aggressive substance from getting on the skin. For additional protection put on regular glasses.
If, for any reason, sulfide gets on the skin, then the affected area must be washed abundantly. running water. The same is done if it gets into the 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-like sulfide is diluted according to the instructions on the label;
- The solid first crumbles to a powdery state, after which it is mixed with water until completely dissolved.
To darken copper, a cold or slightly warm solution is needed. Before you throw 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.
Copper salt changes color.
Put the copper part or product in a container and carefully monitor the reaction. Remove the product only with metal tongs. As soon as the blackening reaches the desired consistency, remove it from the sulfide solution and place it in baking soda to stop the reaction.
If the 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, not 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 the washcloth and rub it well. After that, the product is washed in warm water.
Homemade mortar
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, safety measures must be observed: conduct experiments only in a well-ventilated room, wear gloves and protect your eyes from harmful fumes and splashes.
To obtain green copper, blackening must be carried out with: an empty container, where 0.5 liters are poured. vinegar, 125 ml iodized salt and 375 ml ammonia (pure). The necessary ingredients can be purchased at the store and pharmacy. The amount of salt added affects the saturation of the color. Dip the copper into the prepared composition for a few seconds and carefully monitor the reaction. As soon as blackening suits you, 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. Put a metal object in a container and fill it with the prepared mixture. It is highly not recommended to use sprayers and other methods of applying a soda solution to copper. So you get an uneven color of the copper object.
The wet 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. For this you will need metal container with lid, water, brassware, soda, vinegar and ammonia. Most of the listed ingredients are sold at the grocery store and pharmacy. When conducting experiments, do not forget about safety - use goggles and rubber gloves.
Video: Copper story
Copper is a metal that is not highly reactive and for this reason is often used for decorative purposes. Copper is used to make jewelry, interior items, art, furniture and much more. The surface of the metal oxidizes under the influence of oxygen, however, due to its low activity, this may take decades. The consequence of this reaction is a patina - a surface film, which most often has a greenish tint. Patina prevents metal from damage, 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 copper surface:
- oxidation - the process of formation of oxides and oxides, elements containing oxygen;
- patination - the film is formed under the action of sulfur and chlorine.
If you dip a piece of copper in a solution designed to form a patina on its surface, it will immediately change and, being sparkling new, will look like an old one. 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 wiping method with a towel. This can lead to the fact that there will be remnants of the fabric on the products, water - in the recesses of the relief, 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 sulfuric liver. 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 on fire in a tin. After a few minutes, the powder will melt and, after 15 minutes, will be sintered, while its color will become dark brown. This process may be accompanied by a flame, which is not necessary to bring down.
The first method, in which sulfur liver is used to blacken copper, is as follows: 10–20 grams of the powder is dissolved in one liter of water, or two or three grams if it is necessary to obtain a mild color. The copper product is lowered into the solution until the color changes, then it is taken out, washed and dried. The color turns brown-gray and its shades.
The almost black color of the product is obtained by heating, after treatment 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 lowered 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 with a one-to-one mixture of copper sulfate and zinc chloride. A mixture of powders will need to be mixed in the same amount of water and the copper product should be lowered there for several minutes.
Patination of copper with ammonium sulfide gives a black color. The substance (20 g) is diluted in a liter of water. You can both lower the product into the solution, and apply it with a brush. A surface reaction occurs, 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 is to heat coins or jewelry at 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 is 5-25 minutes. Repeat two or 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 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 smeared with a solution of copper nitrate in a low concentration with the addition of common 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 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 light green, as 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 a temperature of 70–80 degrees. Lower the product and hold until the desired color is obtained.
To obtain a coating with high wear resistance that protects the metal from corrosion, per liter of water is taken in grams: 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 is 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 caustic soda per liter of water. Aqueous solutions of the last two components are prepared separately and only then mixed. Copper sulfide is added only after boiling the mixture. In a solution heated to 90 degrees, put the product for a quarter of an hour.
Obtaining 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, 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. Peeled eggs are crushed and placed in a container with a wide bottom, copper is also placed there. The container closes for 20-30 minutes or more, depending on what color you want to get: for more than long time the product will become darker. The main advantages of this method are simplicity and accessibility. The main disadvantage is that the effect will most likely not be long-term and the coverage will come off.
Patina has excellent properties. For example, in numismatics, the cost of an item depends on how uniform it is. Artificial turf will not replace natural turf.
If the patina has a uniform structure and evenly covers the surface, then it is better to keep 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 very carefully. 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, stains, looks ugly or is heterogeneous, then such methods will do. If you want the patina to lay flat, then the old layer must be cleaned to a metallic sheen.
This composition can be used for cold blackening of parts made of copper and copper alloys.
The coating has good corrosion resistance and can be used as a final finish. If the part is additionally oiled, corrosion resistance can be increased and a deeper, richer 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 there are oxides, grease stains, deep traces of corrosion, etc. on the surface, 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.
To do this, the part after mechanical preparation must be processed in stages with intermediate washing in solutions "UNIVERSAL CLEANER" and "ACTIVATOR".(See "Surface Preparation Instructions"). During the surface preparation processes, it is necessary to carry out high-quality washing of parts. With poor-quality washing, the part after preparation may become covered with an oxide film, on which the coating is deposited extremely poorly.
Blackening of copper
After preparing the surface, 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 lowered 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 rock the suspension with the part fixed to it.
Process parameters
After washing, the parts are immersed in a fixing solution and held there for the required time. During this process, it is also recommended to periodically rock the hanger with the workpiece. Before carrying out the fixing 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.
After the fixing solution, the parts do not need to be washed.
Process parameters
After the fixing solution, the part is dried. After drying, the surface of the part is oiled (by dipping or rubbing) in technical oil with a low viscosity, 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 not a noble metal, but it has long been used in the manufacture of banknotes. Copper is also used as an element of decoration of buildings, furniture and jewelry. Over time, this metal changes its color: it acquires black and brown shades. The darkening of copper is the result of a chemical reaction of the metal surface with oxygen, as a result of which its oxidation occurs. Now, in order for copper to acquire the desired shade, you do not need to wait: humanity has learned by special means and methods to accelerate these oxidative processes. Information on how to blacken copper at home is contained in this article.
What is patina?
Due to the fact that oxygen has little activity, the oxidation process lasts for decades. As a result of this interaction, the formation of a patina is observed - a surface film greenish tint. According to experts, it prevents damage to the metal. Since in ancient times copper was used to make coins, figurines, various souvenirs and household items, today these items that have undergone oxidative processes have a changed color and general view. Blackening of copper is performed in order to give the product an old, and therefore, a rare look, so that when you see it, there is a desire to buy this thing.
About staining methods
Color change is carried out by oxidation and patination. These methods are not synonymous as both processes ultimately yield different results. In the first case, due to oxygen-containing elements, oxides and oxides are formed on the metal surface. In the second, the blackening of copper occurs with the help of chlorine and sulfur.
Preparatory stage
Before you start patinating copper at home, you need to carefully prepare. The copper product is cleaned, degreased, washed and dried. According to experts, it is undesirable to use a towel for this purpose, since particles of tissue may remain on the surface. Due to the fact that very toxic chemicals will be used in the process of blackening copper, the master should adhere to safety precautions:
- For storage of substances, special sealed test tubes must be used.
- Solutions should be out of the reach of children.
- The process should take place in a separate cabinet with ajar doors.
About dyeing with current
Judging by the reviews of home craftsmen, copper-ammonia solutions and sulfurous alkalis are mainly used for blackening. According to experts, the blackening of copper by the electrolytic method is quite effective. Anodizing is carried out in an alkaline soda solution, the concentration of which is 80/o or more. A voltage of 2.5 V with a current density of 01-10 per dm is applied to the bath with a copper product. sq. Electrolysis lasts for 10-20 minutes.
The temperature indicator in the container must be at least 50 degrees. The process can be improved if ammonium molybdate is added to the bath. This soda alkali does not precipitate and is a catalyst for oxidative processes. The amount of ammonium should be within 0.1 a-3/o. Electrolysis lasts no more than 5 minutes. The oxide film is formed in two stages. If the workpiece is removed from the bath in the first phase, then it can be seen that its surface is covered with a gray-steel dense precipitate, which has a metallic tint. No gas is released in this case. If the product continues to be treated with current, the precipitate turns from gray to black.
About the use of sulfuric ointment
Judging by the reviews, home craftsmen often work with copper rings and other small items - pendants and earrings. In such cases, experts recommend blackening copper with sulfuric ointment. According to many masters, the ointment can be applied to the product, and washed off after a while. However, in this case, the result is often unpredictable: it takes a long time to change the color, and it also happens that darkening may not occur. In connection with this fact, many home craftsmen practice blackening with sulfuric ointment vapors. Patination is carried out as follows:
- To work, you need a glass container. A regular liter jar will work well. It must be weighted by placing a stone on the bottom. Metal objects should not be used, as the metal will react with sulfur, which is undesirable.
- Using a plastic or glass rod, draw ointments in the range from 1 to 1.5 cm3. and place in the bottom of the container.
- Make a loop from the forest, into which you then need to thread the patinated blank. The product should not touch sulfur, but stay in a suspended position.
- Close glass container tightly.
- Pour water into a large enameled pan, put a stand on the bottom, on which there will be a jar with a copper product. It is not difficult to make a coaster from a tin lid from a tea can. So that the bubbles formed during boiling do not raise the jar, it is advisable to equip the lid with several holes.
- Put the pan on a gas or electric stove. When the water boils, the heating can be reduced.
The process of blackening copper can last for 2-3 hours. In the course of work, it is necessary to add water to the pan from time to time. In order to provide the product with an uneven patina, experts recommend periodically shaking the jar.
At the end, the processed copper jewelry is removed from the loop, cooled and thoroughly washed in running water. Used liter jar close the lid tightly, since with the remnants of the ointment in the future it will be possible to carry out about seven more patinations.
About homemade blackening solution
Judging by the reviews, many home craftsmen quite successfully blacken copper in vinegar, iodized salt and ammonia. Before patination, the copper product is washed in warm water and dried. You should work with gloves. The room must be well ventilated. Since harmful fumes and splashes are formed during blackening, the master will need goggles. For work, you should acquire the following ingredients:
- iodized salt (125 ml);
- pure ammonia (375 ml);
- vinegar (0.5 l.).
These substances are commercially available. The home craftsman can only go to the pharmacy or garden store for them.
Progress
In order to blacken copper at home, you need to dip the workpiece into the prepared mixture of soda, vinegar and ammonia. In this case, it is important to monitor the reaction. Some masters are controlled in seconds. If the blackening result is not satisfactory, then the processed copper thing in the container can be held longer. For those who want the product to become brown, experts recommend using baking soda and water.
An ordinary bottle is well suited as a container for preparing the mixture. Soda is poured into it until it is completely dissolved. Then the copper product is placed on the bottom of a container. The prepared mixture is poured there. Some craftsmen fill sprayers with it and simply spray their contents onto a copper surface. However, this is not worth doing. In this case, the workpiece will turn out with an uneven copper color. A copper product treated with a solution should be in a plastic bag for some time: from 1 to 8 hours. It all depends on what color the master wants to get.
About blackening with boiled eggs
Considered the most in a simple way which does not require special chemicals. As a result of a chemical reaction from a high temperature in the yolk, sulfur is released.
When it interacts with the metal, the latter acquires a dark brown hue. It will be possible to achieve the expected result if the work is performed in the following sequence:
- Boil a few eggs. Their number depends on the size of the processed product.
- Remove after 10 minutes and refrigerate. After the eggs are carefully cleaned from the shell.
- Cut into several small pieces.
- Put the prepared egg mass on the bottom of the container. A piece of copper is placed next to it.
- Cover the container tightly with a lid.
According to experts, in order for the product to change its shade, half an hour will be enough for it. If the master wants to get a darker color, then the metal needs to be held longer. The disadvantage of this method is the short-term and unstable effect. The achieved result often disappears after a while. Also, the resulting shade will disappear if the copper reagent is a more aggressive chemical.
About patination with potassium sulfide
This method is considered one of the best. The reagent may have a solid, gel-like and liquid state of aggregation. In solid it is stored for more than one year, and in liquid - only a couple of weeks. Sulphide must be diluted in water. The solid is pre-crushed to a powder state, and then filled with water. Metal is dropped into the resulting mixture.
Experts recommend preparing another container with soda diluted in water with a ratio of 1:16. This will stop the aggressive effect of ammonium on the product in time. The reaction will be terminated if the metal is lowered into a container with diluted soda.
How to paint metal with copper sulfate?
With this method, a red-brown film should form. To work, you need three ingredients that are mixed in the following ratio: water (50%), copper sulfate and zinc chloride 25% each.
A copper product is dipped into the prepared solution. To get a white-green plaque, experts recommend additionally using potassium permanganate. For one liter of water, 5 g of this substance will be needed.
The easiest way to blacken copper is with ammonia vapor (ammonia). A thicker color is obtained if the product (the wire is preliminarily kept in a solution of table salt for several hours).
Internet review showed. that this is not the only method. I found most of the information on the forum from ship modellers: http://shipmodeling.ru/
There are actually several ways to get that gorgeous brown patina on your brass or brass. You can use chemicals or more environmentally friendly methods. Some chemicals may be caustic and should be used with care. Then of course there are the more common chemical substances, such as "Sulfur Liver", "Black Max" and antique solutions containing iron nitrate. This is an environmentally friendly way to oxidize copper and silver. The process takes four to six hours.
Using Homemade Ammonia for Copper and Brass
A small, shallow dish on which to place your metal or jewelry items. The container or bag should be large enough to hold a small dish plus hard boiled eggs with room for storage. Two or three hard boiled eggs. . Place your jewelry or metal pieces on a small dish. The egg should not touch metal or jewelry. You will be tempted to look, but don't! Using household ammonia vapor to oxidize metal is indeed quite simple and is an inexpensive way to oxidize copper and copper.
Brings the scale of copper products and the desire to get a good and lasting effect closer to ship modellers. I chose those recipes that forum participants give as proven in practice and for which, in principle, materials can be found:
1. Buy in a store for jewelers or in a store for hunters special compounds for blackening (burning) 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 is still dissolved. Add ammonia until the mixture becomes a bright transparent blue color. The workpiece must be immersed in the solution for several minutes, removed and subjected to heating 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 stable.
4. Prepare a simplified version of the sulfuric liver solution, in which the potash is replaced by soda ash. Here is more 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 at a household chemicals store in a package similar to washing powder), brought to a boil and began to add colloidal sulfur (bought at a flower fertilizer store), also two or three spoons. The yellowish solution began to darken and after 7-8 minutes it turned brown. Either I didn’t calculate with grams in a spoon, or the water boiled away, but in my opinion the required liquid turned out to be not enough and I added more water by eye and boiled it. The final liquid was slightly yellowish-greenish in color. At the bottom there is a thick layer of yellowish sediment. Carefully poured out the resulting liquid.
My guns are made of lead covered with copper. Purchased 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 ready-made reagents, and uniform. Can be polished with a cork brush, but becomes dark dark gray and begins to shine.
5. And, finally, one more recipe (however, there is only a link on the forum, no one 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 add 4 g of a saturated solution of copper sulfate with constant stirring. Well-cleaned copper products are immersed in the hot mixture. Depending on the duration of action, they will acquire a different color - from gold, green to complete black.
Milk sugar is a product baby food. Here is a link to the manufacturer (among the distributors there are addresses of stores in Russia). http://oltri.ru/page102.html
6. And this is just a recipe from the Internet: A 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.
All you need is a clean bath of whipped cream, a lid, a piece of wire or string to suspend your piece and clear the ammonia. It's a little smelly, but if you're fast then the smell shouldn't be a problem. Under no circumstances should metal or finished jewelry come into physical contact with ammonia liquid; it is the pairs that will produce this patina. First of all, clean your piece of brass or copper with alcohol or acetone to remove any oils or dirt so that the patina is uniform throughout.
Do not touch the surface you want to patina. Pour about one inch of ammonia into a pint or quart glass jar. You can use wire or string to hang metal or jewelry directly below the mouth of the jar. The piece must not come into contact with liquid ammonia. Screw on the lid and wait a couple of hours. You can check this piece to see what color you want to stop.
05.09.2009
Oxidation and patination of copper, brass and bronze.
Some chemical reactions lead to the formation of oxides and oxides, i.e., oxygen compounds, on the surface of metals. This process is called oxidation.
Often chemical elements, interacting with a metal or alloy, contribute to the appearance of sulfur or chloride compounds. The process of formation of such compounds is called patination.
If you dip a metal product into the prepared solution, it literally changes color before your eyes. sparkling metal product in a few seconds it takes on the appearance of an antique product.
Most chemical compounds that are used for patination and oxidation of metals are toxic and dangerous to humans. Therefore, they must be stored in vessels with ground stoppers, and all work related to the release of toxic and combustible vapors and gases should be carried out in a fume hood. Cabinet doors should be slightly ajar.
Before changing the color of the metal, some preparatory operations must be carried out. The item is cleaned and degreased, washed well and dried in sawdust. Metal art and coins should never be wiped with a towel. A towel erases fragile patinated films that are not fixed with varnish, moisture remains in deepened reliefs, the fabric catches on high protrusions and can bend them. The sawdust quickly and evenly draws water away from the metal surface.
Patina from gray to black
Preparation of sulfuric liver:
To prepare sulfur liver, you need to mix one part of powdered sulfur with two parts of potash in a tin and put on fire. After a few minutes, the powder will melt, darken and begin to sinter, gradually acquiring a dark brown color. (By the way, the sintering of the patinating mass gave the name "liver" in the old days - from the words "oven", "sinter".)
During sintering, sulfur vapor can ignite with a weak blue-green flame. Do not knock down the flame - it will not degrade the quality of sulfuric liver. Stop sintering after about 15 minutes. For long-term storage, crush sulfur liver into powder and pour into a glass jar with a tight lid.
Method #1
Applies to:
Copper, sterling silver, and bronze or brass (light shade). Does not work on nickel silver.
Colors:
On copper and silver, a range of shades from purple / blue (hard to get) to brown-gray, gray, black. On brass and bronze - only pale golden.
A strong and beautiful patina is formed on the surface of copper treated in an aqueous solution of sulfuric liver.
When making a solution in 1 liter of water, add 10-20 g of sulfuric liver powder. The patina, obtained on the metal with a solution of sulfuric liver, is strong and beautiful, deep black in color. But such intense coloring is not always needed. Sometimes, to give an antique look to a copper product, it is enough to apply a light gray patina. Pour 2-3 g of table salt and 2-3 g of sulfuric liver into a liter of water. Dip a copper plate into the solution. After the appearance of a gray color of the desired tone, rinse the plate with clean water and dry.
Method #2
To blacken a copper thing, a saturated solution of copper sulfate is prepared, ammonia is added to it until the mixture takes on a bright transparent blue color. The copper item to be treated is immersed in this solution for several minutes, then removed and slightly heated until it turns black.
Method #3
The copper thing to be blackened is first cleaned with fine sandpaper, after which they try not to touch its cleaned surface with their fingers. Then it is either immersed in a liquid solution of platinum chloride, or wetted with it with a brush. This solution, if it is not acidic, is slightly acidified with hydrochloric acid.
Method #4
A 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.
Red-brown patina
An aqueous solution of zinc chloride and copper sulphate stains copper red-brown. Mix one part copper sulphate with one part zinc chloride and dilute in two parts water. It only takes a few minutes for the copper to turn red-brown. After washing and drying, wipe the metal surface with oil.
Patina from light brown to black
Blackening of the metal is observed when copper is patinated with ammonium sulfide.
In a liter of water, dilute 20 g of ammonium sulfide. The product is lowered into the resulting solution or watered from above and wiped with a brush. Work is carried out in a fume hood. Sulfur ions in an aqueous solution of ammonium sulfide interact with copper ions. Black copper sulfide is formed.
The intensity of the patinated plaque on the metal can be of a different shade, from light brown to black. The color is adjusted by changing the heating temperature of the plate before patination.
Patina light brown
Gram per liter:
sodium dichromate - 124
nitric acid (density 1.40 gcm3) - 15.5
hydrochloric acid (1.192) - 4.65
ammonium sulfide 18% solution - 3-5
apply with a brush immediately after preparation, rinse off after 4-5 hours and repeat after drying 2 times, polish with a dry rag.
Dark brown to warm black patina
Gram per liter:
ammonium persulfate - 9.35
caustic soda - 50.0
for 5-25 minutes in a bath with a solution heated to 90-95 degrees. rinse, dry, repeat 2-3 times
Olive to brown patina
Gram per liter:
Berthollet salt - 50*70
copper nitrate - 40 * 50
ammonium chloride - 80*100
for 10-15 minutes in a bath with a heated solution up to 60-70 degrees.
the resulting films have mechanical strength and corrosion resistance
Patina brown-black
Gram per liter:
ammonium molybdate - 10
ammonia 25% aqueous solution - 7
the solution should be heated to 60 - 70 degrees
Golden patina
Using more traditional chemicals - safety first!
The smell of ammonia on your piece should fade quickly, but if you want, you can leave the piece for a while before buffing any high points very gently for contrast. Of course, you can use the tried and tested, non-eco-friendly method of adding patina to your metal using chemicals like Sulfur Liver, Black Max and Antique Patina. Some chemicals can be caustic and must be handled with care, both during the patination process and when removing the chemicals thereafter.
Gram per liter:
copper sulfide - 0.6
caustic soda - 180
milk sugar - 180
a solution of alkali and lactose is prepared separately and only then is poured together, boiled for 15 minutes and copper sulfide is added.
place the product in a heated to 90 gr. solution for 15 minutes.
Golden brown patina with raspberry tint and moderate sheen
Take off your work surface and fold the paper because accidents happen. Always have a cup or bowl with clean water at the ready, as well as a bowl with a small amount of baking soda. Paper towels, old T-shirts, or clean rags are ready in case of spills and dry your pieces after you've rinsed off the chemical you're using. Use safety goggles. Yes, no one likes to wear them, but are you willing to compromise your vision for an accidental splash? Have plenty of water. Make sure you have a well ventilated area to work. . Have these things on hand when you "patina" the metal.
After cleaning copper coins, you can create an artificial patina on them by placing 50 g of copper sulfate and 5 g of potassium permanganate per 1 liter of water in a solution, heating it to a temperature of 70-80 ° C and holding it there until the desired color is obtained.
Green patina
You can paint the surface of copper, brass or bronze products green in various ways.
These are sponge pads that contain permanently attached microabrasives. They are used to illuminate the highlighted areas of your patinated figures.
- Cotton swabs, cotton balls, or cotton swabs.
- Brass brush.
- Stainless steel brush.
- You can find them at any grocery store.
- This is my favorite form of liver liver because it is so versatile.
Method #1
The surface of things with a sponge is first lubricated with a highly diluted solution of copper nitrate with the addition of a small amount of sodium chloride. Then, when the thing dries out, it is smeared in exactly the same way with a solution of 1 part potassium oxalate and 5 parts ammonia in 94 parts weak vinegar. Allow to dry again and again lubricate with the first solution; then, after drying, again with a second solution, etc. alternately until the staining has acquired the proper strength.
Before lubrication, the sponge soaked in the solution should be squeezed hard so that it is damp, but not wet. At the end of the surface painting, things are carefully rubbed with hard hair brushes, especially in recesses and crevices. After 8-14 days of work, a brownish-greenish coloration is obtained.
Beyond the world of simple silver and gold lies an incredible landscape of color ready for you to experiment with: patina! Let's take a closer look at how to patina copper. First of all, you want to cook your pieces to be free of dirt and oil for the best results. This means no fingerprints, no oil. If you have access to a brine pan, now is the perfect time to use it. If you're not worried, take a Scotch Brit and gently scratch the surface.
Note that this will give your piece more of a satin finish, but make sure the patina has plenty of room to cling to. After it's clean, stick around the edges so you don't transfer oils onto it. If you've ever done any studio work with copper, you may have noticed that when you heat it up, your metal will begin to change. When copper is heated, some really beautiful colors can be extracted from the metal. reds, purples and blues are all common.
Method #2
Things are rubbed in several steps with a cloth soaked in crude oleic acid (a product obtained in stearin factories). On the surface of things, a dark green layer of oleate copper is first formed, which, under the influence of oxygen and atmospheric moisture, gradually turns into a lighter green copper carbonate.
The process is significantly accelerated if oleic acid is first insisted on copper shavings for quite a long time, and after each lubrication with such acid, after the lubricant dries, lightly (no more than a few drops!) Spray with an aqueous solution of ammonium carbonate with a spray bottle.
The key is to try to stop before you go too far. Try not to get too attached to a certain color until you get it, because it can be frustrating at times. Pull the torch out slowly and you won't be able to get huge coloristic hits. bright until it started to cool. The best thing to do here is to experiment and see what you like and what you can stay with. When you find that a sealant is recommended.
Acrylic clear coats, beeswax wax, or renaissance wax can help protect your surface and color. The ingredients for this patina are easy to find in your kitchen cabinet. Vinegar and salt, about 3 tablespoons each. Stir until the salt has dissolved into the vinegar.
