Products made of copper alloys (brass and bronze) are easy to paint in a dark brown color. A mixture is prepared from 4 ml of ammonia, 5 g of potassium oxalate and 200 ml of vinegar essence. It is necessary to cover the coinage with the prepared composition several times, allowing it to dry completely until it acquires the desired color.
The metallic gloss formed during this treatment soon disappears, and the product acquires an even brown color.
Shades of green can also be obtained using a solution prepared from 5–10 g of verdigris jari, 10 ml of ammonia, diluted in 1 liter of water.
The product is immersed in the solution several times, after which it acquires an olive green color.
For further processing, another 1 liter of water is added to the solution. The coinage is dipped into the bath for several minutes (the interval depends on the desired degree of color), then dried over the fire.
The operation is repeated several times until the metal acquires the desired color.
Products made of copper alloys are painted purple in the following way: the chasing is heated to 70-80 ° C and rubbed with a piece of felt or cotton wool soaked in antimony oil.
The green color of the coinage is acquired after surface treatment with a weak solution of copper nitrate with common salt. After the product dries, it is wiped with a solution of 5 g of potassium oxalate and 10 ml of ammonia, diluted in 100 ml of vinegar essence.
In this sequence, staining should be carried out until the color of the surface becomes dark green. To speed up the reaction, the coinage is heated on fire to a temperature of 50–60 °C.
There is another way: the product ready for coloring is treated with a swab soaked in oleic acid. A layer of copper oxide is formed on the surface, which has a dark green color. After some time, it begins to fade and eventually becomes light green with a yellowish tint. To fix the color, the operation is repeated several times.
All shades of yellow can be obtained by processing the coinage with a neutral solution of copper acetate (yari verdigris).
In addition, the following composition is used: 20 g of caustic soda and the same amount of milk sugar are thoroughly mixed in 1 liter of water and subjected to prolonged boiling. To the mixture gradually add 20 ml of a concentrated solution of copper sulphate.
The solution is allowed to cool and the processed products are placed in it for a short time, after which they acquire a golden hue. This processing method is often used for gold coloring.
A more saturated color with a reddish tint is obtained after rubbing the surface with a slurry of 4 parts of powdered chalk and 1 part of gold leaf, which are diluted with distilled water.
Sometimes a composition containing 15 g of ammonium sulphate, 10 ml of antimony chloride solution and 30 ml of water is used. It must be boiled and filtered several times, the precipitate is mixed in 2-3 liters of hot water. For better dissolution, add caustic soda.
The product is immersed in the bath and held until it acquires the desired color.
The coinage can be dyed silver with a solution of 40 g of tartar and 14 g of emetic stone in 1 liter of hot water. Then 50 g of hydrochloric acid, 125 g of tin powder and 30 g of antimony are added there. The composition is heated and the product is boiled in it until it is covered with an even coating.
Another method of painting - mechanical - requires special equipment and skills. To do this, powder paints or fine metal dust of various colors are usually used; a spray gun, solvents and binders are needed for work, which leave a thin layer of a protective film on the surface of the product.
If all this is not there, then the powders are simply hammered into the metal with a mallet or flat chasing. It is better to repeat this process several times, rinsing the coinage under running water in between.
After this method of painting, surface treatment with varnish is required - colored or transparent, the choice depends on the desire of the master.
It must be remembered that varnishes become covered with cracks and become cloudy under poor storage conditions.
It is possible to apply metal particles to the product with the help of special equipment, under pressure. But this method is very expensive and not always available to the master working at home.
From the book: Korshever N. G. Metalwork
Patination of copper, as well as other methods of its decorative processing (including at home) make it possible to make products made of this metal more attractive, to give them a touch of noble antiquity. It is possible to subject such processing to objects made not only from copper, but also from its alloys such as.
Patination and oxidation
The surface of many metals (and copper is one of them), when interacting with the surrounding air and various chemicals, begins to be covered with a thin layer of oxides and oxides. This process, which also results in a change in the color of the metal surface, is called oxidation. For the most part, the process of metal oxidation occurs naturally, but people have learned to cause it artificially, in production or at home, which is done to give the product an aged look.
Oxidation should not be confused with patination, a process whose essence lies in the fact that a thin layer of sulfur or chloride compounds is formed on the metal surface when interacting with various chemical elements. Patination, which, like oxidation, is accompanied by a change, can also be performed artificially using special formulations for this.
Copper aging occurs naturally over time or immediately when the surface is treated with any preparations.
If under natural conditions the process of oxidation and patina coating of copper or bronze can take years, then when using special solutions, patination occurs in a very short period of time. The surface of the product, placed in such a solution, literally changes its color before our eyes, acquiring a touch of noble antiquity. Using various chemical compositions, it is possible to perform such procedures as blackening of copper, patination of objects made of copper and bronze, blackening of brass in industrial and even at home conditions.
Preparation for processing
Having decided to perform patination or oxidation, you must not only carefully study the question of how to age brass, bronze or blacken copper, but also provide for the necessary safety measures. The overwhelming majority of chemical compounds that are used to carry out such procedures are very toxic and emit vapors that pose a significant hazard to human health. Therefore, for the storage of such substances both in production and at home, vessels with well-ground stoppers should be used, which will prevent the ingress of toxic vapors into the surrounding air.
The procedure itself, carried out to change the color of the surface of the product under the influence of chemicals on it, should be performed in a special cabinet, to which exhaust ventilation is connected. It should be borne in mind that the doors of such a cabinet should be slightly ajar during the oxidation or patination process, which will ensure effective extraction of harmful vapors from its inside.
Products made of copper, brass and bronze should be thoroughly cleaned, degreased and washed in warm water before patination. After the patination or oxidation procedure itself, the treated objects are also washed and placed in sawdust to dry. The use of sawdust is a more gentle method of drying, since doing so with a fabric material can damage the thin film of the formed patina that has not yet been fixed with varnish. In addition, it is practically impossible to qualitatively remove moisture from the recesses on relief surfaces with the help of fabric after patination, and sawdust can easily pull it out.
Color changes of copper and its alloys from gray to black
Gray, dark gray or black and its alloys make the appearance of the product more attractive and presentable. To obtain these colors, the degree of saturation of which can be adjusted, the “sulfuric liver” composition, which has been used for more than a dozen years, is needed. It got its name due to the fact that in the process of cooking it must sinter, that is, turn into a caked mass.
To make such a composition for patination at home, you must perform the following steps:
- one part of powdered sulfur is mixed with two parts of potash;
- the resulting mixture is placed in a tin, which then must be put on fire;
- after waiting for the melting of the powder and the beginning of its sintering, it is necessary to maintain this process for 15 minutes.
In the process of sintering the powder, a blue-green flame may flare up on its surface, which can not be knocked down, since it will not worsen the quality characteristics of the sulfuric liver. After the end of sintering and complete cooling, the resulting mass should be crushed to a powder state. This powder, if placed in a glass jar with a tight-fitting lid, can be stored for a long time.
In order to perform patination of various metal alloys with sulfuric liver, several basic methods are used.Method #1
This method involves the use of an aqueous solution of sulfuric liver. With it, you can change the color of products made from the following materials:
- copper;
- sterling silver;
- bronze and brass.
The colors that can be used to paint the surfaces of products using this method also differ:
- copper and silver - purple, blue (very difficult to get), gray, brown-gray, black;
- brass and bronze - soft golden.
If you did not know before how to age copper and form a strong patina film on the surface of this metal, which is distinguished by a rich black color, use this method. For its implementation, a copper product is placed in a solution consisting of a liter of water and 1–20 grams of sulfur liver powder.
To color copper light gray, the solution is prepared according to a different recipe: 2–3 grams of sodium chloride and sulfuric liver are dissolved in 1 liter of water. A copper product is placed in the resulting solution, the color change of which should be carefully monitored. After the color of the metal acquires the desired tone, the object to be patinated must be washed with water and dried in sawdust.
For patination of copper, you can also use a solution prepared according to the following recipe: ammonia is added to a saturated aqueous solution of copper sulfate and this is done until the liquid becomes clear and bright blue. The cleaned and degreased workpiece is placed in such a solution for several minutes, after which it is removed and subjected to slight heating. After such manipulations, copper should acquire a rich black color.
Method #3To use this method, which also allows high-quality blackening of copper even at home, the workpiece must be cleaned with fine sandpaper. Do not touch the cleaned surface with your hands so that grease spots do not form on it. After preliminary preparation for patination, the object is treated with a solution of platinum chloride or completely immersed in it. In such a solution, if it does not cause an acidic reaction, a small amount of hydrochloric acid can be added.
Method #4To form a strong oxide film on the surface of a copper product, which is distinguished by a rich black color, allows it to be immersed in a composition prepared from nitric acid and metallic copper. To make the color change of the copper part more intense, such a solution can be additionally heated.
Obtaining a patina of other colors
To form an oxide film of a different color on copper, you can even use one of the following methods at home.
Red-brownTo obtain a red-brown oxide film, a copper product is placed for several minutes in a composition prepared from one part of copper sulfate, one part of zinc chloride and two parts of water.
To obtain such a patina, a copper object must be placed in a solution consisting of one liter of water and 20 grams of ammonium sulfide. By changing the heating temperature of the workpiece before patination, it is possible to regulate the intensity of staining.
Light brownTo give the surface of a copper product a light brown color, it is necessary to treat it with a mixture of sodium chromium peak (124 g / liter), nitric (15.5 g / liter) and hydrochloric (4.65 g / liter) acids, 18% ammonium sulfide ( 3–5 g/liter). This solution is applied with a brush and aged for four to five hours.
Bronze(chemical). - This is the name of copper alloys with tin in various proportions (copper in excess), then copper alloys with tin and zinc, as well as some other metals or metalloids (lead, manganese, phosphorus, silicon, etc., in small quantities). The presence of foreign metals in real bronze (copper-tin alloys) is sometimes random and is due to the incomplete purity of the source material (some examples of ancient bronze), but usually the addition of a certain amount of certain substances is done knowingly, for specific purposes, and then such bronze receives special names (manganese bronze, phosphor bronze, etc.). From the addition of tin, copper becomes more fusible, hard, elastic, and therefore sonorous, capable of polishing, but less malleable, and therefore bronze is mainly used for casting various objects. The quality of bronze depends on the composition, methods of preparation and subsequent processing. If alloys of copper with tin, containing from 7% to 15% of this latter and the most common in practice, are subjected to slow cooling, then the separation of the alloy occurs and the part richer in copper solidifies earlier; such a phenomenon, called segregation of bronze, is a great hindrance in the casting of large bronze objects; it can be eliminated to a certain extent by the addition of certain substances (for example, phosphorous copper, zinc) or by rapidly cooling the cast objects (conversely, the admixture of lead causes an easier separation of the alloy, so an increase of this latter over 3% should be avoided). When bronze is quenched, a completely opposite phenomenon occurs to that observed for steel: bronze becomes soft and to a certain extent malleable.
The color of bronze, with an increase in the percentage of tin, changes from red (90% - 99% copper) to yellow (85% copper), white (50%) and steel gray (up to 35% copper). As for ductility, at 1% - 2% tin alloys are forged in the cold, but less than pure copper; at 5% tin, bronze can only be forged at a temperature of red heat, and at a content of more than 15% tin, malleability completely disappears; alloys with a very high percentage of tin again become somewhat soft and ductile. The tear resistance depends partly on the composition, partly on the state of aggregation, determined by the method of cooling; with complete uniformity and the same composition, bronze with a finely crystalline structure has a greater ability to resist. The specific gravity of bronze is usually greater than the average of the specific gravity of the constituent parts, and varies from forging and more or less rapid cooling. According to Riche's research, the alloy corresponding to the SnCu3 formula has the highest sp. weight 8.91 (therefore, when it is formed, the greatest compression occurs); its structure is crystalline, the color is bluish; when cooled slowly, it remains perfectly homogeneous; apparently, there is a certain chemical compound here. The SnCu4 alloy possesses similar properties. Under the influence of humidity and carbon dioxide of the air and similar reasons, over time, bronze sometimes develops an excellent bluish-green coating, or a layer of basic copper salts, so valued in bronze objects by connoisseurs and bearing the name Aerugo nobilis, Patina, Verde antico. Patina protects the bronze from further change; whether its bronze composition has an impact on the speed of appearance is a moot point; it is known that the formation of patina can be accelerated artificially, but only to the detriment of beauty. Not so long ago, the question was raised about the fact that bronze statues in large cities (London, Berlin) either turn black directly, or the green patina formed on them gradually acquires a darker, almost black color. The commission, convened on this occasion in Berlin, decided that such a phenomenon depends on the smoky and dusty atmosphere of large cities, where buildings are heated mainly with coal containing sulfur compounds. To preserve the statues, it is recommended to clean them with a solution of spermaceti in gasoline. 
antique bronze was known much earlier than brass; in very remote times, as is known, it was used for making weapons, coins, various ornaments, etc. (Bronze Age). Bronze was then obtained by smelting copper and tin ores, and therefore ancient bronze often contains, in the form of impurities, iron, cobalt, nickel, lead, zinc, silver, etc. The oldest bronze, golden in color, contains approximately 88% copper and 12% tin (F. Wibel, "Die Cultur der Bronzezeit Nord- und Mittel-europas", Kiel, 1865). 
Cannon or artillery the metal consists (in round numbers) of 90 -1 parts of copper and 9 - 10 parts of tin (it also sometimes contains small amounts of zinc and lead). Alloys with this composition are very prone to segregation. Oud. the weight of artillery metal containing 10% tin is 8.87. Bronze for tools should be distinguished by hardness, toughness, elasticity, high tear resistance and possible indifference to chemical agents; alloys of the indicated composition satisfy these requirements, but only to a certain extent. The so-called Uchatsius steel bronze (Stahlbronze) contains 8% tin. To increase the tear resistance, such bronze is subjected to strong pressure, driving a steel cone of larger diameter into the drilled cannon mouth with a hydraulic press. 
bell metal differs from the previous one by a high content of tin; its average composition: 78% copper and 22% tin; beats weight 8.368. The content of silver in some bells is an accidental or excessive admixture: it is mistakenly thought that silver increases the sonority of bells. An alloy of copper and tin of the specified composition has all the properties that can be required from a good bell, i.e. sonority, sufficient hardness and strength (resistance to tearing). In a fracture, it is fine-grained, yellowish-gray in color) fusible, brittle. The known tone of a bell depends on its shape, casting, and composition. The alloys used for the manufacture of musical percussion instruments and for the Chinese tam-tam or gong-gong have a composition similar to bell metal. The special sonority of Chinese instruments is achieved by rapid cooling of the alloy (hardening) and prolonged forging. 
New statue bronze. The use of foundry work of bronze, consisting only of copper and tin, in addition to the comparative high cost, presents quite a few other inconveniences: such bronze is rather difficult to melt, does not mold so well, and easily undergoes segregation during solidification, which is unfavorably reflected in the appearance of the cast objects and on the formation of a uniform layer of copper salts (patina); moreover, it is difficult to process with a cutter. These inconveniences can be eliminated by a certain change in the composition of bronze, and therefore, at the present time, when casting statues, part of the tin in bronze is replaced by zinc. Alloys with 10% - 18% zinc and 2% - 4% tin are distinguished by a beautiful reddish-yellow color, they perform well the slightest depressions in the form, there is enough viscosity for processing and they acquire a beautiful green coating (patina) from the action of atmospheric influences. A higher content of tin makes bronze too brittle, and from an excessive addition of zinc, it loses its color and becomes covered with an ugly dark coating of metal compounds. From the admixture of lead, bronze becomes more workable, but already at amounts above 3%, the alloys are very easily segregated. According to D "Arce, bronze, consisting of 82% copper, 18% zinc, 3% tin and 1.5% lead, is most suitable for casting statues. Normal Elster bronze contains 862/3% copper, 62/3% tin, 31 / 3% lead and 31/3% zinc.
Phosphor bronze, proposed by Künzel in 1871, consists of 90% copper, 9% tin and 0.5% - 0.5% phosphorus; used for casting cannons, bells, statues, bearings, various parts of machines, etc. The addition of phosphorus (in the form of phosphorus copper or tin) increases the bronze's resilience, tear resistance, and hardness; the molten metal is easy to cast and performs mold wells. By changing the weight ratios of the constituent parts, it is possible to give the alloys the desired properties: to make them soft like copper or viscous like iron, and hard like steel; from shocks and shocks, the structure of phosphor bronze does not change; with a phosphorus content of more than 0.5%, its color is golden.
aluminum bronze- alloys of copper with aluminum, containing from 5% to 10% aluminum and 90% - 95% copper. The color of bronze, with a content of 5% aluminum, is very similar to gold; in addition to beauty, it is distinguished by many other excellent qualities (by the way, alloys with 8% - 5% aluminum are very malleable). Five grades of aluminum bronze are commercially available, with varying degrees of toughness and tear resistance; it resists oxidation and sea water well, much better than other alloys. The admixture of silicon changes the color and properties of aluminum bronze. As a material for the manufacture of various parts of machines, it displaces phosphor bronze in paper mills and gunpowder factories ("Jahresber. ub. d. Leist. d. chem. Technol.", 1890, 359).
Flint bronze has the same resistance to tearing as phosphor bronze and has a high electrical conductivity, is used for telephone wires. Weiler's silicon bronze (for telephone wires) contains, according to Gampe's analysis, 97.12% copper, 1.62% zinc, 1.14% tin, and 0.05 silicon.
manganese bronze obtained by fusing manganese cast iron (ferromangan) with copper, then with copper and zinc, or with copper, zinc and tin. Bronce Company in England manufactures five varieties of it, which differ from each other in their properties (hardness, viscosity, tear resistance) and are used for various purposes (Heinzerling, "Abriss d. Chem. Technologie", 1888).
In addition to these grades of bronze, there are other alloys with various applications; such is, for example, bronze for mirrors, medals, coins, bearings and various parts of machines, etc.
Using a simple chemical treatment, a multi-colored protective and decorative coating is obtained on the surface of the product. A small product is immersed in a container with a chemical solution as a whole, a large product is treated with a brush, sponge, foam rubber. In order for the resulting film to hold on to the product more firmly and not to be covered with plaque, after washing and drying it is wiped with a rag soaked in machine oil or drying oil.
In order not to experiment every time while waiting, in search to obtain the required color tone on a particular material, stock up on samples of steel, copper, brass, aluminum plates treated with one or another solution, indicating their recipes.
Decoration of ferrous metals
Finished products made of ferrous metals need decorative and protective coatings, the technological qualities of which determine their attractiveness and durability.
When processing ferrous metals, especially by the forging method, a layer of scale forms on their surface, at first glance, a beautiful gray-blue color. But this coating does not protect the metal from corrosion, but is iron oxide.
Having a different thickness and density, it is subject to gradual flaking from the main product, so the scale must be removed. This can be done in different ways. For example, in a chemical way, using a solution of hydrochloric acid, hexamine and potassium iodide in various proportions. Or mechanical - emery, a metal brush, a fine-grained file, a mixture of water and ground pumice. After cleaning and drying, the product is oxidized by heating its surface with a burner or blowtorch. On it color tones from yellow to dark blue are formed. Having received the desired shade, the heating is abruptly stopped. Given the different thickness of the product, oxidation can achieve different color shades on its different parts. After oxidation, the product is coated with wax dissolved in gasoline. After drying, polish with a hair brush. The black color of the metal can be obtained by rubbing the purified metal with vegetable oil and heating until a film of the desired shade is obtained. The oil must not ignite; decomposing from heating, it densely fills the pores of oxides, forming a reliable coating of black or dark brown color. Products of garden and park architecture, which are constantly exposed to atmospheric influence, are covered with paint and varnish coatings.
Coating with automotive sealant, which is applied to the primer, has proven itself well. Steel can be painted dark blue in an aqueous solution of inosulfite and lead acetate: per liter of water - 150 g of sulfite and 50 g of lead. Easier staining occurs when the solution is heated to a boil. With the help of this solution, brass is given a silver-blue tint.
The strict beauty of blued steel is known, when the metal acquires a blue-black color, like a raven's wing. At the same time, burnishing is one of the best ways to protect against corrosion. Along with silver polished to a mirror surface and shot gold, blued iron was revered as heraldic metal. It was these types of decorative processing that were used to create coats of arms, as well as artistic royal or princely weapons.
To obtain black steel with a blue tint, 100 g of potassium dichromate is dissolved in a liter of water, which is commonly called chrompic by craftsmen. The steel product is kept in this solution for 20 minutes and dried over a flame or high temperature heat. A gray-brown tint appears. By repeating blueing, a blued color is achieved.
A black matte surface is also obtained by chemical oxidation in a solution of the following composition: per liter of water 80 g of sodium hyposulphate (potash), 60 g of ammonium, up to 7 g of phosphoric acid, 3 g of nitric acid.
The dark brown color of the metal is obtained by oxidizing 15 g of ferric chloride, 30 g of ferrous sulfate and 10 g of copper nitrate in a liter of water. The metal begins to change color to brown. Repeated oxidation will result in a thick black-brown color.
Oxidation at room temperature lasts up to an hour, with heating of the oxidizing solution - it is reduced by a factor of three.
The blue color of steel is obtained by oxidation in a solution of 120 g of water, 30 g of ferric chloride, nitric mercury, hydrochloric acid and 120 g of alcohol; at a 20-degree temperature, the oxidation time takes 20 minutes.
Before any oxidation method, the oxide layer must be decapitated with chemical solutions (3-5-pro-resin solution of hydrochloric or sulfuric acid in water), as well as cleanly degreased with acetone or gasoline. These operations are to avoid grease stains or other surface contamination. Products are processed in solutions on wire suspensions and washed under running water to wash off the acid.
In addition to chemical oxidation, they also use the thermal method of decorating ferrous metals, as well as non-ferrous metals, from which products intended for use in a dry room are made.
When the product is heated with a gas burner, shades of tint (color variability) change on it - from straw to black. On the required color, the master stops thermal tinting of the metal. For oxidation by heating the surface of the product in an individual workshop, a simple gas burner with a wooden handle is used, connected by a flexible hose to a gas cartridge. Such a burner can be made by yourself. A homemade burner consists of a nozzle, a plug and a primer (as in a gas stove burner), a tube and a handle. The nozzle (with internal thread) and plug (with external thread) are easiest to make from brass on a lathe. Air holes are drilled on the side of the nozzle. In the cork, which is connected to the nozzle by a thread, two holes are drilled and threads are also made in them for the tube and primer. The handle is put on and fixed on the tube, which is connected to a flexible hose with a thread. The supply (strength) of the gas flame is regulated by a tap on the cylinder. When working with a gas burner, precautions are necessary: you need to make sure that there are no side fires, there is no gas leakage and there are no explosion and fire situations. Color gamut, toning, color transitions can be achieved by the skillful use of a burner. In this way, both chased and other products or works of mixed media are tinted. After heat treatment, the products are covered with a wax layer (wax with a solvent) and polished with felt and felt.
Oil-oil firing is usually used to apply a decorative and protective black-brown coating on cast iron products - sculptural works, figured lattices for fencing parks, flower beds, and others. Products are moistened with drying oil, and then calcined. This method of decoration is also used for works created by artistic forging, since in blacksmithing, when working with ferrous metals, the master often has to stumble upon rust. Depending on the degree of damage, rust is removed mechanically or with solvents of the appropriate intensity. Partially affected areas of the metal are cleaned with emery, after wetting them with kerosene. Rust that has covered a large area is removed with a solution based on phosphoric acid, the content of which determines its intensity. The solution is applied with a prepared swab on a holder, and after drying, the place of rust is treated with an iron brush.
Recipes for solutions of various concentrations
Weak: in a liter of water 15 g of concentrated phosphoric acid, 5 g of butyl or ethyl alcohol;
Average: 700 g of water, 200 g of phosphoric acid, 160 g of technical alcohol, 70 g of washing powder.
Strong: per 100 g of water 275 g of phosphoric and 15 g of tartaric acid, 6 g of potassium nitrate, 3 g of chromic anhydride, 8 g of zinc phosphate and 3 g of thiocarbamide.
To remove rust from works of artistic value, for their restoration, sparing solutions are used that can remove rust and minimally damage the main part of the restored product. The preparation of such solutions is feasible in a private workshop. This is almost a natural, minimally chemicalized preparation, which is prepared in a 5% solution of hydrochloric acid from crushed leaves and stems of medicinal herbs - celandine, marshmallow, yarrow, as well as tomatoes and potatoes.
The acid solution should cover the crushed herbal mass. Covered with a lid, this tincture is aged for 7-10 days. After that, a rust pickling solution is prepared by mixing 5 g of the extract obtained as a result of infusion, 40 g of concentrated hydrochloric acid and 75 g of water. These proportions, if necessary, are easily changed to obtain an even more gentle pickling solution: 10 g of extract, 20 g of acid, 100 g of water (inversely proportional change).
Protective tinting of non-ferrous metals and alloys
Particularly susceptible to tinted coatings are copper and its alloys: brass and bronze.
The black (gray) color of copper and brass can be imparted using various oxidizing solutions.
Sulfur liver is obtained by fusing in a porcelain cup one part of powdered sulfur with two parts of dry potash for 15-20 minutes. When reacting with air, the components of the melt interact. Keep sulfur sintered with potash longer in large pieces - the activity of this sintering is better preserved - in dark glass vessels, hermetically sealed. An aqueous solution of sulfuric liver (potassium polysulfide, also used for the oxidation of silver in order to give it a stable sulfide film) is prepared from 10-15 g of sulfuric liver per liter of water (store no more than a day). The product is tinted by immersion in dissolved by dipping with a rag, then the application of the solution to the product is easier to control, and, therefore, to regulate the depth of staining of the metal surface.
The black color of copper is also given with a solution of this composition: for 100 ml of water - 0.9 g of caustic soda and 0.3 g of ammonium persulfate - at a temperature of not more than 100ºС.
The old masters carried out the blackening of copper according to the following recipe: a solution of copper sulfate is mixed in equal amounts with ammonia (the mixture becomes bright blue), the product is dipped into it for several minutes, then, having been removed, it is heated until the copper turns black.
The same procedure is in such compositions: a solution of pure copper in nitric acid; saturated solution of copper sulphate with the same amount of carbonic soda, then, after obtaining a precipitate of copper carbonate, the liquid of the solution is drained, and the washed precipitate is dissolved in ammonia.
Blackening of copper can be carried out by dipping the product into a solution of ferric chloride in the ratio of one part of it to one part of water.
Gray color is obtained in a solution of 2-3 g of sodium chloride and the same amount of sulfuric liver in a liter of water.
The most saturated color of oxide films on copper - from light brown to brown-black - can be obtained by preparing a solution in combination with ammonium sulfide and sulfuric liver, respectively, in various doses - from 5 to 15 g.
The chocolate color of copper and brass can be given in a solution of potassium chloride, nickel sulfate and copper sulfate - respectively 4.5 g, 2 g and 10.5 g per 100 ml of water when the solution is heated to 100ºС.
A brown color with a reddish tinge is obtained in a solution of 2.5 g of antimony pentasulphide in a liter of 4% sodium hydroxide.
The red-brown color of brass is given by an aqueous solution of zinc chloride and copper sulphate in an equal ratio of parts of zinc and sulphate.
Brown and black color on brass is obtained by treating the product with a solution of 60 g of hyposulfate and 5 g of nitric, sulfuric or hydrochloric acid in a liter of water. Such a solution has a tinting effect for only 20 minutes.
Olive and black-brown color will give brass treatment with a solution of copper oxychloride and ammonia.
Brass turns black in the following solution: 2 tablespoons of copper oxychloride are mixed with two-thirds of aqueous ammonia in a liter of water; this solution must be quickly stirred and corked. A mixture of greenish color will be obtained, and after precipitation - blue-green; in this solution and tinted brass; while the alloy does not lose its luster. The processing time does not exceed a few seconds.
Orange-red in a few minutes, a brass product will make a solution of 5 g of potassium sulfide in a liter of water.
In the old days, brass was also given other, it would seem, completely unexpected colors for this alloy.
Violet color was obtained by immersing the product in a solution of antimony chloride; chocolate-brown - by firing with iron oxide and subsequent polishing with a lead sheen.
The color of the antique patina of works made of copper, bronze and brass can be given by treating them in a solution of 50-250 g of ammonium chloride and 100-250 g of ammonium carbonate per liter of water. It is also possible to do this with the following composition: 64 g of ammonium chloride, 132 g of medium acetic salt and copper and a liter of 5% acetic acid.
A gray-green tint is created with a solution of five components: 50 g of sulfuric liver, 75 g of ammonium chloride, 50 g of iron acetic salt, 60 g of ammonium, 35 g of 5% acetic acid per liter. The black-green color is obtained by replacing the acetic salt of iron with the acetic salt of copper.
Blue-green, close to malachite, the color will create such a solution: 40 g of ammonium chloride, 160 g of sodium chloride, 120 g of potassium tartrate and 200 g of copper nitrate.
The azure color of brass will give a few minutes of being in a solution of 3 g of lead acetate, 6 g of hyposulfite (sodium thiosulfite) and 5 g of acetic acid in 100 ml of water at a temperature of 80ºС.
Copper will turn green in a solution of 20 g of copper nitrate, 30 g of ammonia, 40 g of ammonium carbonate, the same amount of sodium acetate in 100 ml of water (sodium acetate is a mixture of soda and vinegar).
Ammonium in an individual workshop can be tinted in several ways. We will describe those available to a private master, since the electrochemical processing of this metal requires special equipment.
The product, previously treated with alkali (caustic potash or sodium), is washed and treated in potassium tartrate with alkali, then immersed in a solution of 130 g of copper sulfate or 5 g of zinc chromate, 3-5 g of nitric acid and 15 g of zinc fluoride, mixed in a liter of water; aluminum takes on a yellow to golden color.
There is also a way to tint aluminum in a golden color. Coated with a layer of molten paraffin, aluminum is fired with a blowtorch.
Sometimes the product is rubbed with linseed oil or vegetable oil and held over a smoky torch made of roofing felt or roofing felt, which emit resinous soot, the particles of which are firmly connected by hot linseed oil, forming a sulfur color of the coating, and the flame should not touch the metal.
By calcination, products rubbed with drying oil or vegetable oil are also tinted. The resulting shiny film of a certain color will reliably protect the metal from corrosion and give aluminum a piquant decor.
Products coated with vegetable oil will acquire an olive color, with drying oil - red-brown or brown-black.
The easiest way to tint aluminum with simultaneous protection against corrosion is to coat products with oil paints. The color variation here is the richest. But this method is applicable only for aluminum.
But calcination is used in the decoration of steel and cast iron.
Lead is stained gray (dark gray) with citric or acetic acid using a swab on a wooden stick. Usually, small items are made from this metal and its alloys of hart and babbit by casting. The product, dyed to the desired tinting, is washed under the tap and dried.
It is known that some plants (herbs) contain various acids in their juice. So, celandine juice contains more than 4 percent of organic acids, including citric, as well as chelidonic, malic and succinic acids; getting on the skin, it causes irritation, burns. Celandine juice is used for blackening small items made of various metals, including lead and zinc.
Zinc tinting is produced in different colors due to its good reaction with other substances that give colored compounds. Zinc is engravable, good for casting, and, as already mentioned, it is conveniently tinted. Zinc is given, among other decors, the look of old silver.
Gray color is obtained with weak solutions of acids. For example, a teaspoon of citric acid and the same amount of copper sulfate in a glass of water. "Lemon" can be replaced, the color is given by treatment with a solution, which includes 1 part of tartaric acid, 2 parts of soda and 1 part of water. This solution is mixed with clay, coated with a product, and after drying, washed in water.
Brown-bronze color is obtained with a composition of 1 part verdigris and 5 parts of acid. The surface is also rubbed with a mixture, dried and washed off.
Copper color gives zinc wetting with vitriol, since zinc is more active than copper.
If you wipe zinc with hydrochloric acid and sand (as an abrasive for preparatory cleaning), and then dip it into a solution of 3 parts of wine-rock-copper salt, 4 parts of caustic soda and 48 parts of distilled water at 10 degrees temperature, then, depending on the residence time of zinc in solution, completely different colors can be obtained on it: 2 minutes - purple, 3 minutes - dark blue, 4-5 minutes - golden yellow, 8-9 minutes purple-red.
The blue color of zinc can also be obtained by a solution of 6 g of nickel sulfate and the same amount of ammonium chloride in 100 g of water.
Zinc becomes green in such a solution: 10 parts of copper sulfate, the same amount of tartaric acid, 12 parts of water plus sodium hydroxide dissolved in water (1:15) - 24 parts.
Zinc can also be made black; for this, the metal must be treated with a solution that includes the following components: 2 parts of copper nitrate, 3 parts of copper oxide, 8 parts of hydrochloric acid and 65 parts of water.
In this way, it is possible to tint (paint, patinate) not only pure zinc, but also galvanized iron.
And in conclusion of the section on decorative metal trim. If it is necessary to lighten some fragments of the relief of the embossing, details of a sculptural metal work or products made using a different technique of artistic metal processing, these parts are wiped with a swab with fine brick powder (as a fine abrasive that removes oxide contamination), moistened with a tinting solution to create an initial tinting - an even, perfect clean layer of primer. This method is especially suitable for finishing embossed products.
There is no need to achieve an absolutely black (opaque) film: no matter what color the coating is, the metal should still seem to look through it, hinting even through the decor at its original appearance.
Metallic painting
You will need:
Sponge with a "scratching" texture;
Ordinary sponge (for smooth surfaces).
For this painting, I used a latex horn.
After degreasing the surface, apply the darkest matte paint - I usually use black. At this stage, you need to paint over the product as carefully as possible, without leaving white dots - this may require painting in two stages. Apply the first coat with a brush, moving along the texture, painting over all the depressions. Let the paint dry - while it is wet and glossy, you may not notice that you have missed some areas, if necessary - add a second coat. Black color imitates patina.
The next layer is applied metallic, starting with the darkest color, in our case it is antique bronze. If at the first stage the paint should be a little watery and paint over everything as much as possible, and you need to move along the texture, then here the paint should be as dry as possible and you need to apply it across, not allowing it to fall into the recesses. For application, a sponge with a large “scratching” surface is optimally suited. In the absence of such, you can get by with an ordinary sponge, but before each application of paint to the product, wipe off the excess - for example, on paper.
The paint is applied with short, scratching movements, highlighting only the most protruding areas; stamping movements. The “newer” the product should look, the more metallic should be applied. When painting smoother, non-textured surfaces, I apply the last coats with a regular sponge to make the surface look more uniform and polished. This painting principle mimics what happens to real metal: patina accumulates in depressions, and metal is visible in raised, polished areas.
You can stop at the previous stage. If you want to give the product a more interesting look, you can add other colors. We still apply them with a scratchy dry sponge, trying to cover even less of the surface than in the previous step. Here, the second layer was applied on the Emerald Decolor, the third (only on the ends of the horn rings) - Gold Heraldry.
Wood painting
You will need:
Several shades of matte acrylic paint (black, brown, ocher, etc.);
Ordinary sponge.
The painting scheme coincides, with minor reservations, with the previous one. In this case, an amulet made of self-hardening plastic was used. Horizontal grooves were applied to the amulet at the sculpting stage to imitate the texture of wood.
1. After degreasing the surface, apply black paint with a brush, making sure that there are no white areas left.
2. We apply a second coat of brown paint (in this case I used a regular sponge), trying to paint over most of the recesses, but not completely.
3. We apply the third layer of lighter paint (ocher is suitable) using a sponge. Before each application of paint, we remove the excess on a sheet of paper, so the paint on the sponge turns out to be small each time and it is quite dry, therefore it affects only the protruding parts of the product, bypassing the recesses. It can be applied with stamping movements; scratching movements across the recesses.
4. The final touches are applied with a brush with the lightest paint (for example, yellow or ocher, slightly diluted with white). We lead the brush strictly vertically, in the direction of the grooves, imitating the pattern of wood (still without going into the recesses).
Several light stripes parallel to each other add a more "wooden" look.
lava paint
You will need:
1. We paint the part in a solid red color. We try to paint as carefully as possible.
2. With a thin brush, paint over the most important recesses in red, gently shading.
3. Using the thinnest brush, paint over the center of the recesses in yellow (in the case of other schemes, you can use, for example, white). You can add glowing paint to enhance the effect.
We apply black with a “scratching” sponge - with dry paint, across the recesses, without going deep.
The more "cooled" lava you need, the more black you should use.
Artist: Sergey
