Chemical solutions for pickling iron and steel

The simplest effective solutions for etching iron and steel parts are dilute inorganic acids, especially 20% sulfuric acid, in which etching is carried out at 45-50 ° C, or 20-25% hydrochloric acid, in which parts are etched at room temperature. For etching, 10-15% phosphoric acid is also used, heated to 60-70°C. Parts are etched in it, which will then be varnished or their surface will be left without further processing. If, after etching, galvanic coating of the surface is provided, then this bath is unsuitable.

Chemical etching of non-ferrous metal surfaces

Etching copper and brass

On brass the solution forms a light yellow coating, on copper it forms a light pink coating. The solution contains:

Concentrated nitric acid 250 ml;
- Concentrated hydrochloric acid 150 ml;
- Denatured ethyl alcohol 100 ml;
- Water 500 ml.

The parts are etched by briefly immersing them in a bath of solution, after which they are removed and immediately washed with water.

Brushed copper etching

After etching on copper, you will get a rough (to matte) surface. Bath composition:

Nitric acid 40% 600 g;
- Concentrated sulfuric acid 400 g;
- Sodium chloride 3 g;
- Zinc sulfate 2 g.

Brilliant etching of copper and its alloys

Concentrated sulfuric acid 500 ml;
- Concentrated nitric acid 500 ml;
- Concentrated hydrochloric acid 10 ml;
- Soot 5 g.

The operating temperature of the bath is 18-20°C. The degreased parts are immersed in a bath of solution for 10-30 s, after which they are removed, washed with water and dried.

Solution for etching aluminum and its alloys

The aqueous solution contains:

Sodium fluoride 40 g/l;
- Caustic soda 50 g/l.

The operating temperature of the bath is 70-80°C, the processing time is about 1 minute.

Another aqueous solution contains

Chromium oxide 30 g/l;
- Concentrated sulfuric acid 150 g/l;
- Operating bath temperature 70°C, treatment time 1-1.5 minutes;

The simplest way to decoratively paint steel products

Electrochemically you can paint steel products in any color. If the paint layer is varnished, it will reliably protect the product from corrosion. The solution in which steel products are painted includes the following components:

Copper sulfate 60 g;
- Refined sugar 90 g;
- Caustic soda 45 g;
- Water up to 1 liter.

Copper sulfate is dissolved in 200-300 ml of distilled water, then sugar is added to the resulting solution. Separately, caustic soda is dissolved in 250 ml of water and a solution of copper sulfate and sugar is added to it in small portions (with stirring). After mixing these two solutions, add distilled water to 1 liter. The part is cleaned, polished and degreased in a solution used for nickel plating, and then thoroughly washed in warm water. An additional electrode is made from red copper (preferably grades M0, M1). The part and electrode are connected to a flashlight battery (or other 4-6 V DC source), and the copper electrode should be connected to the plus of the battery, and the part to the minus. First, the copper electrode is lowered into the solution, and then the part. After 5-10 s, the battery is turned off, and coloring continues without electric current. While in the solution for 2 to 25 minutes, the part is painted in following colors(in order of appearance): brown, purple, blue, cyan, light green, yellow, orange, red-purple, greenish-blue, green, rose-red. The part can be removed from the solution (checking the color) and put back into the solution - the process will proceed normally. When the part is kept in the solution for more than 25-30 minutes, the process is repeated cyclically many times.

As the electrolyte evaporates, distilled water is added to the bath, since increasing the electrolyte concentration worsens the quality of the color. To obtain more contrasting colors, add 20 g of sodium carbonate (anhydrous soda) to the finished electrolyte. If the painting is unsuccessful, the film can be easily removed by wiping the part with ammonia. The painted parts are washed with water, dried and coated with colorless varnish.

Easy way decorative finishing aluminum surface with mother-of-pearl effect

The aluminum surface is cleaned wire brush, making small strokes in different directions(creating a specific pattern). Chips and dirt are removed from the surface with a clean rag. A clean aluminum surface is coated with an even layer of 10% caustic soda solution (working temperature of the solution is 90-100°C). After the solution dries, a beautiful film with a pearlescent tint forms on the aluminum surface. For better preservation, the film is coated with colorless varnish. A more beautiful film is obtained if the product or part is heated to 80-90°C before applying the caustic soda solution.

Chemical method of brightening products and parts made of silumin (restoration)

Products and parts made of silumin (an alloy of aluminum and silicon) are quickly covered with an oxide film of dark tones. However, they can remain shiny for a long time if they are lightened. Products or parts are cleaned and, if necessary, polished, then degreased, washed and immersed for 10-20 minutes in the following solution:

Chromic anhydride 100 g;
- Concentrated sulfuric acid 10 g;
- Water up to 1 liter.

The working temperature of the solution is 18-20°C.

After lightening, the products and parts are washed and dried, and so that the surfaces of the products and parts do not oxidize for a long time, they are coated with colorless varnish.

What you need to know about polishing steel and non-ferrous metals

Polishing is used to improve the cleanliness of the surface of parts and devices, and to eliminate traces of previous processing (strokes, scratches, small dents and tiny irregularities). There are two types of polishing - preliminary and final. Pre-polishing is used for mechanical removal surface irregularities due to loose abrasives (in a free state) or grains fixed to work surface polishing wheel. Final polishing is carried out with fine grinding powders or soft elastic wheels with thin polishing pastes applied to them. The finest surface finish is achieved by rubbing a piece of felt or woolen cloth coated with a special metal polishing paste. After polishing, the surface acquires a mirror shine.

Lime paste is used for polishing nickel, brass, aluminum and other metals, its composition (in%) is as follows:

Vienna lime 71.8;
- Ceresin 1.5;
- Stearic acid 2.3;
- Solid oil T 1.5;
- Turpentine 2.2;

Composition of paste (in%) for polishing steel and other metals:

Paraffin 20;
- Stearin 10;
- Technical lard 3;
- Micropowder M50 67;

Note

Waxy and liquid materials are mixed and heated in a water bath (or over low heat). Then the dry ingredients are mixed into the hot mass.

GOI pastes are intended for polishing steel and other metals and are chromium oxide mixed with waxy substances. Pastes are produced in three grades: coarse, medium and fine. In the absence of chrome paste, you can successfully use chromium oxide oil paint diluted with kerosene. Crocus paste (iron oxide) is sold in stores in ready-made form (in dentures it is used under the name “gold paste”). Crocus paste is used for polishing brass, bronze, silver and other metals. "Shine" powder diluted with machine oil is used for fine polishing of metals.

Chemical method of polishing metals

Metals can be polished chemically, i.e. by simply immersing the part or object in a bath of polishing solution without using electric current. For this purpose, you can use porcelain glasses or baths. The polishing solution consists of the following substances:

Concentrated phosphoric acid 350 ml;
- Concentrated nitric acid 50 ml;
- Concentrated sulfuric acid 100 ml;
- Copper sulfate or nitrate 0.5 g.

The operating temperature of the bath is 100-110°C. Polishing time from 0.5 to 4 minutes. When polishing, choking fumes are released, so the bath should be located in a fume hood or on outdoors.
This solution polishes aluminum and its alloys well. It is also suitable for polishing other metals, but the operating conditions (polishing time, temperature) must be different.

CHEMICAL PROCESSING OF METALS

Chemical nickel plating of steel, copper, brass and bronze products
Parts made of steel and copper alloys can be chemically coated with nickel. This coating not only protects parts well from corrosion and gives them a beautiful appearance, but also has increased wear resistance. The advantage of chemical nickel plating is that nickel is evenly deposited on all, including internal, surfaces of parts.
The part to be decorated with nickel plating must be prepared in an appropriate way: sanded, polished and degreased. Steel parts are degreased in a solution containing 20-30 g of caustic potassium (or caustic soda), 25-50 g of soda ash and 5-10 g of liquid glass (silicate glue) per 1 liter of water; copper - in a solution containing (for the same amount of water) 100 g of trisodium phosphate and 10-20 g of liquid glass. Before nickel plating, copper parts must be kept on the iron for 0.5-1 minutes. It should also be borne in mind that alloys containing more than 1-2% lead or cadmium are not amenable to chemical nickel plating.

Degreasing of steel and copper parts at room temperature ends after 40-60 minutes, at a temperature of 75-85°C - after 20-30 minutes. Then the part is thoroughly washed in running water and immersed for 0.5-1 min in a 5% solution of hydrochloric acid to remove the oxide film, after which it is washed again in water and immediately transferred to the nickel plating solution. 30 g of nickel chloride and 10 g of sodium acetate are dissolved in 1 liter of water heated to 60°C. Then the temperature is brought to 80°C, 15 g of sodium hypophosphate is added - and the solution is ready. The part is immersed in it, the temperature is raised to 90-92°C and maintained at this level until the end of the nickel plating process. At lower temperatures, the speed of the process slows down sharply, and when heated above 95°C, the solution may deteriorate.

Required quantity(volume) of the solution depends on the area of ​​the nickel-plated part. The ratio of this area (in square decimeters) to the volume of the solution (in liters) should be in the range of 2.5-3.5.
So, for example, at S/V=3 in 1 hour the thickness of the nickel layer will be 10 μm.

The chemicals used are not toxic, degreasing and nickel plating are not accompanied by the release of harmful gases.
Chemical copper plating steel and cast iron parts

Quite easily, copper is chemically deposited on iron, steel and cast iron. The coverage is satisfactory.

To coat these metals, a solution of the following substances is prepared:

Copper sulfate 8-50 g;
- Concentrated sulfuric acid 8-50 g;
- Water up to 1 liter.

Operating temperature 18-20°C. After thorough cleaning and degreasing, the parts are immersed in the solution for a few seconds. Parts coated with copper are removed from the solution, washed with water and dried.

Chemical chromium plating of metals

Parts made of steel, copper and brass are chemically chrome plated in a solution containing:

Chromium fluoride 14 g;
- Sodium hypophosphate 7 g;
- Sodium citrate 7 g;
- Glacial acetic acid 10 ml;
- Caustic sodium (20% solution) 10 ml;
- Water up to 1 liter.

Operating temperature is about 80°C. Cleaned and degreased parts are metallized within 3-8 hours. When chemically chrome-plating steel objects, it is recommended to first chemically coat them with copper. Parts with a deposited layer of chromium are washed in water and dried.

Electroless nickel plating of metals

The nickel plating solution consists of the following substances:

Nickel ammonium sulfate 50 g;
- Ammonium chloride 40 g;
- Water up to 1 liter.

A small amount of zinc metal is added to the solution and stirred continuously.

Chemical dyeing of pewter items bronze

Pewter products can be easily painted bronze using a chemical method. Products are immersed in a solution or wiped with a cloth soaked in a solution consisting of the following substances:

Copper sulfate 25 g;
- Ferrous sulfate 25 g;
- Water up to 500 ml.

Then the product is dried, cleaned with a brush, wiped with a cloth and again immersed in a solution consisting of the following substances:

Copper acetate 100 g;
- Acetic acid 10% 400 ml.

After this, the product is dried. If desired, it can be polished and coated with clear varnish.

"Gold plating" of brass

Brass and products made from it quickly tarnish and oxidize in air. To protect highly polished products from oxidation, brass parts are often coated with a special golden varnish. Simpler and affordable way is as follows: after thorough cleaning and polishing, a brass part is immersed in a 10-15% solution of some alkali to remove fat from its surface. Then the part is washed in water and immersed in a weak (2-3%) solution of sulfuric or hydrochloric acid for 1-2 s. Good results are obtained if brass is dipped in a solution of sodium bisulfite, then rinsed in water and dipped in a solution of copper acetate heated to 36-40°C.

Depending on the time the piece is in the solution, the brass will turn from a light golden color to a red gold color and even a reddish-violet hue. The color of the paint is monitored by removing the part from the solution from time to time. After painting, the part is washed with water and air dried. The color is permanent and does not change over time. Copper acetate is commercially available, but you can make it yourself. To do this, you need to dissolve 5 g of copper sulfate in 0.5 liters of water, then mix it with a solution of lead acetate (pharmacy lead lotion or lead sugar).

The second solution is made up of 8 g of lead acetate and 0.5 liters of water. When mixing the solutions, a precipitate of lead sulfate precipitates, and copper acetate remains in the solution. This solution will serve as the working solution. The precipitate can be filtered or left at the bottom of the vessel.

Copper gold coloring

4 g of caustic soda and 4 g of milk sugar are dissolved in 100 g of water, boiled for 15 minutes, then with constant stirring, 4 g of a solution of saturated copper sulfate is added in small doses. Well-cleaned copper products are immersed in the hot mixture. Depending on the duration of action, they acquire different colors - from gold, green to complete black.

Golden varnish for brass (passivation of brass)

When brass is passivated, a stable protective film similar to gold plating is formed. This film is not afraid of moisture, so fishermen passivate brass lures. The cleaned, polished and degreased part is dipped for 1 second in a solution prepared from 1 part nitric and 1 part sulfuric acid, and immediately transferred to a strong solution of potassium dichromate (chrompic) for 10-15 minutes.

After this, the part is washed and dried.

Chemical staining of brass

The cleaned, degreased and washed part is dipped into one of the following solutions.

1st solution:

Hyposulfite 11 g;
- Lead sugar 39 g;
- Water up to 1 liter.

Solution temperature 70°C.

2nd solution:

10 g of sodium hydroxide and 10 g of milk sugar are dissolved in 250 ml of boiling water. Then, stirring continuously, add 10 ml of a concentrated solution of copper sulfate to the solution.

Within 3-10 minutes, the part in one of the solutions turns golden, bluish, blue, violet and, finally, rainbow.

When the desired color is obtained, the part is removed, dried and polished with cloth.
Brass acquires a bluish-black color when the prepared part is immersed for 1-3 minutes in the following solution:

Ammonia (25% ammonia) 500 ml;
- Bicarbonate (or carbon dioxide) copper 60 g;
- Brass (sawdust) 0.5 g.

After mixing the components, the solution is shaken vigorously 2-3 times, after which the part is immersed in it.
IN brown brass is painted by immersing the part in one of the following solutions.

1st solution:

Hyposulfite 50 g;
- Copper sulfate 50 g;
- Water up to 1 liter.

Solution temperature 70°C.

2nd solution:

Sodium sulfide 100 g;
- Water up to 1 liter.

Solution temperature 70°C.

3rd solution:

Lead acetate 30 g;
- Hyposulfite 90 g;
- Water up to 1 liter.

The solution temperature is 80-90°C.

To prepare the 3rd solution, you need to dissolve both substances separately in half the volume of water, then drain them together and heat to 80-90°C. After painting the part is washed warm water, dried and coated with colorless varnish.

A simple method of silvering

Spent hyposulfite (fixer) is used as a silvering compound, which is no longer suitable for fixing photographic films or photographic paper. The method is extremely simple. The copper part is cleaned to a shine, boiled in a soda solution and thoroughly washed with water. Then it is dipped into used hyposulfite. After some time, silver will settle on the part. After washing with water, the part is dried and polished with cloth. The quality of silver plating and the strength of adhesion of silver to copper depends on the concentration of silver in the hyposulfite solution.

Hot silvering of metal parts

Any metal can be silvered using this method. It consists of the following: a cleanly processed part is immersed on a zinc strip in a boiling solution consisting of the following components:

Potassium iron sulfide 120 g;
- Potash 80;
- Silver chloride 7.5 g;
- Distilled water up to 1 liter.

The silvering process ends after the surface of the part is completely covered with silver. The part is then removed from the solution, washed and polished. It should be remembered that when the solution boils, harmful substances, so boiling should be done in the open air or under a hood.

Chemical silver plating

1. Several sheets of Unibrom matte photographic paper are cut into pieces and dipped into a solution of fixing salt (the salt is diluted in the volume of water indicated on the package).

The cleaned and degreased part is placed in this solution and rubbed with an emulsion layer of paper until a dense layer of silver is formed on the surface of the part. After rinsing in warm water, wipe the part with a dry cloth.

2. Add 1-2 ml of ammonia and 2-3 drops of formalin to 300 ml of used fixer (remaining after printing photographs) (the solution is stored and worked with only in the dark).
The cleaned and degreased part is placed in the solution for 0.5-1.5 hours, then washed in warm water, dried and wiped with a soft cloth.

Paste for silvering

Parts made of copper, bronze, brass, and copper-plated iron can be plated with silver using pastes.

1. Paste for silvering is prepared as follows: in 300 ml of distilled water or water obtained from ice in household refrigerators, dissolve 2 g of silver nitrate (lapis) and add a 10% solution of table salt to the solution until precipitation stops silver chloride precipitate. This precipitate is washed 5-6 times in running water. Separately, 20 g of hyposulfite and 2 g of ammonium chloride (ammonia) are dissolved in 100 ml of distilled water. Then silver chloride is added to the resulting solution in small doses until it stops dissolving. The resulting solution is filtered and mixed with finely ground chalk to the consistency of thick sour cream. The pre-degreased part is rubbed with a paste using cotton wool or gauze until a dense layer of silver is formed on its surface, after which the part is washed with water and wiped with a dry rag.

2. The polished and degreased part is rubbed with a cloth or a piece of soft leather, onto which a paste of the following composition has been applied:

Silver chloride 6 g;
- Table salt 8 g;
- Sour potassium tartrate (tartar) 8 g.

The listed substances are ground in a mortar and stored in a dark container; before use, the mixture is diluted with distilled water to obtain a liquid paste. When the part is covered with a layer of silver, it is washed in water and rubbed until shiny with soft flannel.

3. Paste for silvering is prepared as follows: pour 2 g of ammonia into a vessel, 4 g cream of tartar and 1 g of silver nitrate (lapis), add a little distilled water to obtain a semi-liquid slurry. Then, with a cloth with paste applied to it, the polished and degreased part is rubbed to a silver shine.

Chemical method of silvering non-metallic materials

Non-metallic parts, such as plastics, glass, ceramics, wood, etc., can also be metalized chemically. The solution given below for silvering non-metallic materials gives very good results, especially when metallizing glass (silvering of mirror surfaces, vessels, incandescent lamp bulbs, reflectors for projection equipment, etc.).

The silver bath contains the following substances:

Composition A

Silver nitrate 12 g;
- Ammonium nitrate 18 g;

After complete dissolution of the substances, the solution is added with distilled water to 750 ml.

Composition B

Caustic soda (chemically pure) 19 g;
- Distilled water 500 ml.

After complete dissolution of caustic soda, the solution is added with distilled water to 750 ml.

Composition B

Sucrose 12.5 g;
- Tartaric acid 1.5 g;
- distilled water 125 ml;

The solution is boiled for 20 minutes, and then added with distilled water to 500 ml.

All solutions are stored separately in dark containers with ground-in stoppers.

The solution for silvering is prepared by mixing compositions A and B, to which composition B is added immediately before silvering. The parts intended for silvering are thoroughly cleaned in a hot soda solution, rinsed with running water and immersed in a bath with a freshly prepared solution. The working temperature of the solution is 18-20°C. Silvering time - 10 min. Metallization can be carried out two or three times in succession, but each time in a fresh solution. Silver-plated parts are dried at a temperature of 50°C for 1 hour, and at a temperature of 18-20°C for 24 hours. The silver layer can be easily removed from glass, porcelain or ceramics with nitric acid.

Chemical dyeing of silver objects purple

Silver or silver-plated objects acquire a purple color in a solution consisting of the following substances:

Anhydrous sodium sulfate 12.5 g;
- Sodium carbonate 5 g;
- Water 500 ml.

The solution is heated to 80°C and the object is immersed in it for a few seconds. The item is then allowed to dry. The surface of the object can be coated with transparent varnish.

Chemical solution for dyeing silver objects black
Silver or silver-plated objects become black after boiling them in a solution of sodium sulfate (100 g per 500 ml of water). After boiling in this solution, the objects are dried and coated with a clear varnish.

Hot gilding of metal products

Mix 20 g of nitric and 20 g of hydrochloric acid in a glass vessel. 1 g of gold is dissolved in this mixture. When the gold dissolves, 1 g of antimony chloride and 1 g of pure tin are added to the solution. The vessel with the solution is placed in hot water and boil until the tin dissolves, then add 20 g of a saturated solution boric acid. Products intended for gilding are cleaned, polished and boiled in a solution of caustic potassium or soda. The solution is applied to the product with a brush; The dried product is heated over the flame of an alcohol lamp or over a charcoal fire. After heating, a good gilding is obtained that does not require polishing. Store the solution in a glass container with a ground-in stopper in a dark place.

Gilding without external source current Contact gold plating is used to obtain very dense and uniform coatings, characterized by high adhesion strength, and if a large coating thickness is not required. Electrolysis by this method does not require an external current source. The potential difference required for gold deposition is created by a galvanic cell, in which the cathode is the coated product, immersed in a gold-plating electrolyte, and the anode is a zinc plate located in a concentrated solution of table salt and connected to the product with a wire, as shown in Fig. 1. Any heated gold-plating electrolyte from those indicated in the table can be used for electrolysis.

Gilding by immersion is based on the creation of a potential difference at the boundary of the surface of the metal being coated and the adjacent electrolyte layer. Coatings good quality are formed only on brass or brass plated parts. Therefore, parts made of other metals are pre-brass-plated ( minimum thickness layer 1-2 microns). The gilding process automatically stops when a gold layer with a thickness of about 0.1 microns is obtained, but the coating is dense, glossy and has good adhesion to the surface of the parts.

Compositions of solutions and operating modes for gilding using the immersion method

Removal of poor-quality gold coatings

To remove poor-quality coatings, gold-plated silver items are suspended as anodes in a 5% solution of hydrochloric acid at a temperature of 18-20°C. Iron or lead plates serve as cathodes. Anodic current density 0.1 - 1 A/dm?. Copper pendants. In addition, the gold coating can be removed in aqua regia. " Aqua regia"is a mixture of acids (50% nitric acid mixed in 50% hydrochloric acid). The mixture is used for etching copper, brass, iron, steel, zinc, etc. This solution acts on metals almost instantly; corrosion and dirt are caused by disappear, and the surface of the metal becomes shiny or, more often, matte. Jewelers use this mixture to determine pure gold.

Note

When using active acids, safety rules must be strictly observed. It should be remembered that when diluting an acid with water (for example, sulfuric acid), you need to pour the acid into the water, and not vice versa, since otherwise the acid will splash, which can lead to severe burns.

Simple ways extracting silver from waste hyposulfite (fixer)
Only part of the silver contained in the photosensitive layer of the photographic material is consumed to construct a photographic image. Most of the silver goes into the fixer and developer; it can be isolated and collected.

1st method.

Allows you to highlight pure silver. It consists of the following: iron filings or small iron nails, well washed from grease with gasoline, are poured into a vessel with depleted fixer. Shake the solution from time to time. After 7-10 days, the solution is drained and the nails are dried in air. Silver deposited on nails falls off as a black powder, which can then be smelted into ingots.

2nd method.

The depleted fixer and an equal volume of spent metholhydroquinone developer are poured into one vessel. A 30% solution of sodium hydroxide is added to the resulting mixture at the rate of 100 ml for each liter of used fixer. The silver is deposited in the form of the finest pure silver powder. The process lasts at least 48 hours.
The silver precipitate formed during this time is filtered and dried. The remaining aqueous solution of sodium thiosulfate, i.e. fixer, can be used again in work.

3rd method.

A polished brass sheet is placed in the used fixer, which is in a glass vessel. After 48 hours, almost all of the metallic silver from the depleted solution will have deposited on it. After deposition, the sheet is washed well with water and dried. Then the layer of silver is carefully scraped off its surface.

4th method.
To 1 liter of used fixing solution add 5-6 g of sodium hydrosulfite and 5-6 g of anhydrous soda. After 19-20 hours, the metallic silver formed in the form of a black fine powder is filtered, and the desilvered fixing solution is acidified with sodium bisulfite and used again for work.

5th method.
To do this, prepare a 20% solution of sodium sulfate and pour it into the used fixer at the rate of 20 ml of solution for each liter of fixer. After thoroughly mixing the solution, it is allowed to stand for 24 hours. Then the solution is drained from the sediment, and the sediment is dried on paper. The precipitate is silver sulfide. Precipitation is carried out in the open air or with increased ventilation; to reduce the release of hydrogen sulfide, the spent fixing solution is pre-alkalinized.

COLORING OF METALS

Coating metal with moiré varnish
Before coating with “moire” varnish, the surface of the metal part is degreased by heating it in an oven (oven) for 15-20 minutes at a temperature of 80-100°C, then primed with heat-resistant enamel, puttied with varnish putty and dried. When the part is thoroughly dry, it is treated with pumice with water and sandpaper, wiped dry, coated with an even layer of “moire” varnish using a spray bottle and placed for 10-15 minutes in an oven at a temperature of about 80°C.

The pattern of the pattern depends on the thickness of the coating and the duration of heating of the part. Once the pattern has formed on the part, it is removed from the oven for a short time to allow partial cooling, and then placed back into the oven to final dry the varnish. At a temperature of 120-150°C, the varnish finally dries within 30-40 minutes, and at a lower temperature - within 2-3 hours.
To protect the painted surface from dust, it is coated with celluloid varnish: celluloid is dissolved in acetone to the consistency of liquid oil varnish and applied to the surface in an even layer using a swab. After the acetone dries, a strong protective film remains on the surface.

A durable coating is obtained if BF-2 glue is added to aluminum paint. BF-2 glue is dissolved in alcohol until the enamel becomes thick, then dry aluminum powder is poured into the resulting solution and mixed thoroughly, after which alcohol is added again until normal viscosity is obtained.

The paint prepared in this way adheres well when painted with a brush or with a spray gun, it does not crumble and retains its appearance for a long time.

Painting steel products to look like aluminum

To give steel products beautiful view and to protect them from corrosion, the metal is often coated with aluminum paint - a varnish with aluminum powder. To do this, 15 g of powder is poured into colorless nitro varnish diluted with acetone (110 g).
In the same proportion, the paint can be diluted not in nitro varnish, but in celluloid glue - acetone, in which 5-10 g of X-ray film, cleared of emulsion, is dissolved.
The surface of the product is first thoroughly cleaned and then a thin layer of paint is applied using a spray gun.
A durable coating is obtained if BF-2 glue is added to aluminum paint. BF-2 glue is dissolved in alcohol until the enamel becomes thick, then dry aluminum powder is poured into the resulting solution and mixed thoroughly, after which alcohol is added again until normal viscosity is obtained. The paint prepared in this way adheres well when painted with a brush or with a spray gun, it does not crumble and retains its appearance for a long time.

What you need to know about paint incompatibility and the peculiarities of paint color perception

All paint components - chemicals. Metals (copper, zinc, aluminum), which are part of paints in the form of powder, affect the corrosion of the metal surface being painted and the binder. Metal oxides and salts affect the binder, accelerating film formation. Dissimilar types of binders cannot be combined with each other, and some oil paints, obtained with the same binder, but based on different pigments, cannot be mixed.

Pigment incompatibility. When mixing pigments, it is very important to consider the nature of their interaction. If pigments are incompatible, they are destroyed and their anti-corrosion properties are lost.
When mixing paints with incompatible pigments, their color is lost.

Incompatibility of binders. You can mix oil paints only with oil paints (on a homogeneous basis), glypthal - with glypthal, pentaphthalic - with pentaphthalic, epoxy - with epoxy, bitumen varnishes - with asphalt and coal tar varnishes, etc. However, all thick oil paints can be diluted with drying oils and varnishes made on the basis of only light natural and artificial resins, excluding asphalt and bitumen resins.
Incompatibility of paint with surface material. All primers without exception can be applied to a steel surface: oil, phosphating, tread, glyphthalic, phenol-formaldehyde, vinyl chloride copolymers, ethylene, acrylic, etc.

I have been looking for a long time for an acceptable method of blackening metal that could be used at home and obtain acceptable blackening quality.

The most affordable option seemed to be to buy a can of matte black paint and paint over the necessary parts. But even this method is not so simple. We need to prepare the environment, and definitely not in the apartment, but at least in the garage. And besides, the paint can be easily scratched.

I will generally keep silent about the anodizing method; it requires increased safety precautions and all sorts of experiments with sulfuric acid do not suit me.

Just recently I learned about the method of blackening with ferric chloride. Purely by chance - at the market one person said that he puts shiny parts in etching treatment printed circuit boards and thus gets a good blackening. I thought good idea, but in general it is not necessary to look for work, it is enough just to find ferric chloride (FeCl3) and make the same solution.

I found ferric chloride and ordered it online from a private seller on a bulletin board; a 200 g bag cost me about 50 UAH with postage.

I was pleasantly surprised, since ferric chloride is mainly sold for radio amateurs. I myself used to be interested in radio engineering, about 15 years ago, and I thought that now this industry had long been supplanted by Chinese ready-made radio solutions. It turned out that they were not forced out, since there is a supply for ferric chloride, there is also a demand. But I won’t go off topic, further on…

I ink aluminum, duralumin, steel and brass using this method. And I can say that it worked best with aluminum. A little worse, but acceptable, the duralumin was blackened. The steel did not turn black, but became covered with a coating reminiscent of rust, it stopped shining, at least this way, it was still a little better than it was. The brass changed color a little - it became a little redder, stopped shining, became matte, but did not turn black.

Method of blackening aluminum with ferric chloride

I needed to blacken a couple of duralumin rings for macrofur and a couple of aluminum adapters. For such a small number of parts, 15-20 grams of ferric chloride is sufficient.

Ferric chloride in a container for preparing a solution

First you need to dilute it with a small amount of water. For such a small amount of iron, very little water is needed. It is important that the resulting mixture is thick. so that it does not spread but is spread on the surface. I did it by eye - the thicker the solution, the better.

While the solution is “infused,” we prepare our parts for blackening. We clean them from possible dirt and dust and degrease them. I just washed them with soap under the tap, that was enough.

Now that the solution is ready, take some kind of stick. for example, for cleaning ears with cotton wool on the tip. and spread it carefully internal surfaces adapter I only ink them, preferring to leave them shiny on the outside. Make sure that the solution remains on the surfaces and does not run off.

Part with ferric chloride solution applied

In my case, the aluminum parts turned black after 7-10 minutes. The duralumin took a little longer to darken, maybe 20 minutes, but I didn’t track the exact time.

The duralumin ring has darkened

As a result, the surface became dark gray and matte. Doesn't glare, which is what we wanted.

If you are not satisfied with the result, you can rinse the parts and go through again with the remaining solution. I did this with duralumin, steel and brass, in the hope that it would turn out better.

Dural began to look noticeably better, steel and brass remained the same. You can also leave them spread for a longer time.

After achieving blackening, the parts can be washed with running water and dried. Then you can use them.

The surface of the same ring after washing and drying. I'm happy with the blackening.

After I blackened the macro bellows ring, which was initially shiny, the contrast in the photos improved a lot, especially when shooting black details with long exposures.

Another aluminum part, blackened using the same method

But what happened to the brass: It didn’t darken at all, but became dull and changed color a little

Here is a relatively simple and high-quality blackening method. I hope that it will be useful not only to me, but also to other enthusiasts.

The boss once set me a task. It is necessary to make a duplicate keyboard to control the machine controller, since the factory one quickly became unusable because it was made of transparent self-adhesive film, onto which a design is applied at the factory.

I work at a small enterprise that produces spices. I am engaged in servicing packaging machines, electrical equipment, local network etc., in short, all the technology, smart and not so smart.
So there you go! After much thought and debate with the boss, I finally convinced him that for our lammer-operators the keyboard case would be best suited from “alloy gun steel”, :cool:, but in the absence of it we decided to use a high-strength aluminum case type 203-125B , dimensions 121x66x35 mm from Pros Kit.

Idea

The milling machine ordered aluminum buttons. The case was purchased from a store. And then the question arose of how to make indelible inscriptions on the buttons and body. I tried to scratch it and fill it with paint. It came out completely “meh”! Can be engraved! So I don’t have a Dremel, but I can’t help but search through friends.

Laziness, my friends, is the most powerful engine of progress. After some thought, I remembered that I had once accidentally dripped ferric chloride onto an aluminum radiator. While I wiped away the drop, there was a stain on the radiator and a small indentation. Yeah...

What if you make a stencil from photoresist and then etch it? The guinea pig was a piece of duralumin plate. Everything turned out great!

Preparing the surfaces

Let's start with preparing the surfaces. First we sand dry with sandpaper No. 80-100, spreading it on a flat substrate, then we remove large scratches with an emery sponge No. 180-200, moistening the surface and sponge with water. From time to time we rinse everything with water.

Rice. 1. Surface preparation.

I was quite happy with this roughness. If desired, you can polish it.

Rice. 2. Case and buttons after polishing.

Rolling photoresist

Next, we measure out the photoresist for the body and buttons.

Rice. 3. Film photoresist.

I can't say anything about the photoresist. I bought it from an online store. All that was indicated: “Film negative indicator photoresist.”

We measure a little with a margin around the edges so that it is convenient to roll. Film photoresist consists of 4 layers: the bottom (it’s matte) is polyethylene, then a thin layer of glue, then, in fact, the photoresist itself, and the top is glossy protective layer(lavsan). Carefully pry up the matte layer with a needle or scalpel, tear off a strip 5-8 millimeters wide and glue it to the body. It is easier to roll the photoresist along the length of the body.

Yes! One more nuance. It is better to heat the housing over gas to a temperature of approximately 40 degrees. Then the photoresist sticks better. Gradually tearing off the base, we roll the photoresist onto the surface with a hard photo roller, or, at worst, with your finger. We cut off the protruding edges of the photoresist with a file to the body or a sharp knife.

Make sure that no dust particles or air bubbles get under the photoresist. In this place, ferric chloride may get in and there will be a problem. If air bubbles do occur, you can carefully pierce them with a sharp needle and roll them firmly with a photo roller.
We do not remove the top protective layer yet, because the photomask may stick to the photoresist (there have been cases).

Rice. 4. Rolled photoresist.

Making a photo template

Next, use any convenient program to prepare a photo template and print it on transparent film for printers. When printing, we indicate the maximum contrast and minimum brightness, but here you have to try. I have an Epson RX610. The settings are as follows: print quality " Best photo", "Shades of gray", paper type "Epson Matte", brightness: -25, contrast +25.

Photoresist is negative! That is, where there is no paint on the template, the photoresist will glow and will not wash off during development! Be careful.

Rice. 5. Photo template. I use film sparingly. Therefore, I print different projects on one sheet while there is space left.

Illuminate with a UV lamp

We apply a photomask and press it with glass onto the photoresist.

Rice. 6. Preparing for exposure.

Hide the buttons before exposing them. If they light up, you will need to re-roll the photoresist.
We illuminate the photoresist with a UV lamp. Exposure time is about 1 min.

Rice. 7. Photoresist exposure

Rice. 8. After illumination, the contours of the drawing appear.

We illuminate the buttons in the same way. Now you can remove the top protective film of the photoresist.

We show

Next is development. We prepare a solution for development from: a household glass jar 0.5 l - 1 piece, soda ash (not baking soda) - 0.5 teaspoon, hot tap water - 0.5 l (full jar).
Stir the solution until the soda is completely dissolved. Then we take a not very hard clothes brush, dip it into the solution more often and brush it almost without pressing over the photoresist. The unexposed photoresist is gradually washed off and this is the picture you get:

Rice. 9. Developed photoresist.

We poison in ferric chloride

We cover exposed areas of metal that do not need to be etched (for example, the ends) with colorless nail polish (you can steal it from your wife, like I did). Now we take a photo bath, pour in ferric chloride and throw the body and buttons there with the image DOWN.

Rice. 10. Etching.

The solution immediately begins to bubble. Aluminum displaces iron from the solution and it settles right there, at the site of etching. It should be removed with a soft, unnecessary toothbrush approximately once every 30 seconds. In this case, you need to be careful: chips of the photoresist may appear at the edges of the image. If this happens, immediately rinse, dry and correct the chip with a waterproof marker or the same nail polish. However, the varnish can corrode the photoresist, so be careful.

I etched for about 5 minutes. After etching, I get indentations about 0.5 mm deep.
We remove the photoresist. When making printed circuit boards, photoresist can be removed with a solution of caustic soda (caustic soda) or slightly diluted “Mole” for cleaning sewer pipes. But this is not suitable for aluminum. It darkens on contact with caustic. If the etched recesses are deep, then you can remove the photoresist with an emery sponge and water, if not very deep, then you can throw it in a bowl with acetone or solvent No. 646 or 647 for 15-20 minutes.

Rice. 11. After etching and removal of photoresist.

Final operations

Next we cut out the holes for the buttons.

Rice. 12. The holes are ready.

We seal the outline around the inscription with construction tape. I didn’t have construction tape, so I sealed it with aluminum.

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Laser engraving on metal

We often get asked the same question: can Endurance lasers engrave metal, such as aluminum or steel.

Is it even possible to engrave metal at home?

Today we will answer this question.

Consider aluminum. In fact, it is a fairly common metal in everyday life, suitable for engraving. Many products, for example, keychains, flash drives, and some mobile cases have an aluminum coating.

What do we know about aluminum? This is a metal with a melting point of about 600 degrees Celsius, has high thermal conductivity and, as a rule, has on its surface a film of aluminum oxide, which has a melting point of more than 1000 degrees Celsius. This makes engraving by heat treatment much more difficult, but there is another option. Aluminum – good guide, and if so, then no one has canceled the electrolysis process. This is the very solution that we will tell you about.

This process is called aluminum etching.

There's nothing complicated about it. We only need a 9-12 volt power source.

And also ordinary table salt NaCl, a dielectric container (plastic is fine), a nail or any iron object of a suitable shape and size, water.

And, of course, the Endurance laser. We used it for these purposes, but any other will do.

So what do we do?

We are preparing a raster pattern that we would like to apply to the aluminum surface of the plate.

For example, this one:
1.

2. Cover the aluminum surface of the plate protective film(adhesive tape, tape, varnish, paint, your choice).

3. Place the aluminum plate on the desktop of a 3D printer or desktop laser engraver equipped with our (2.1W or 3.5W) laser, and turn on the mode laser cutting(to destroy the pasted film and create open areas in the place of future engraving).

4. Next, prepare a concentrated aqueous solution of NaCl in a plastic container.

5. From the source of electric current we bring out 2 wires “plus” and “minus”.

6. We attach an iron object (nail) to the minus and lower it into an aqueous solution of NaCl.

7. We attach our aluminum plate to the plus and also lower it into the salt solution.

8. Apply power to the current source.

9. The process of electrolysis (etching) in the solution begins. Depending on the current strength and solution concentration, you can estimate the approximate time required for etching. Usually 3-5 minutes.

10. Remove the product from the solution.

You can do the same and even better! Find out more!

It must be remembered that before placing the engraved product in the solution, it should be carefully isolated, with the exception of those areas where, in fact, the engraving should be applied.

This process can be carried out both at home and in a small workshop.
With this technology, anyone can become a master metal engraver.
In our opinion, this technology has great practical value, since you can laser engrave metal with relative ease at home or in a small workshop.

Engraving on metal (aluminum and steel) is easy with Endurance!

Aluminum etching demo video

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+ All our lasers engrave on leather, acrylic, plastic, plywood, wood.
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Etching various parts at home from copper is already quite well known to modellers. But I always didn’t like the fact that the parts obtained using this method most often need to be painted - after all, for example, copper is practically not used in aviation.
How much more interesting it would be, I thought, if the parts were made of white metal, and besides, this metal is in literally"lying under your feet."
I tried many times to etch aluminum from beer cans, but it didn't work out well. However, I finally got a result that allows me to think that not everything is so hopeless.. ;)

The material used was a cut Red Bull Cola can. I read that some modellers prefer Red Bull because the foil on the cans with it is thinner.

The etching solution was the familiar “Mole”, which is often used to remove paint from models.

The protective layer was a laser printer toner applied with an iron from a backing sheet from self-adhesive film. This method is well known and I will not describe it in detail.

The aluminum can is coated on both sides with a protective layer. I removed this layer from one side sandpaper.

Why one? Yes, because before that I deleted from both sides. But it’s not for nothing that “Mole” is used to remove paint. It peeled off the protective layer on the back side, which I made with white nitro, and I got unpredictable double-sided etching instead of single-sided

Therefore, I decided to use the transparent protective layer located inside the can on the other side for protection.

The design was transferred to the cleaned surface with an iron and the plate was sent for etching.

At first I etched aluminum with ferric chloride, but achieved good results I couldn't. In the article “Chemical milling of metals” based on materials from the book “The ABC of Ship Modeling” I read: “It is better to etch aluminum and its alloys in a 10-15% solution of caustic soda. It should be remembered that chemical milling occurs very slowly. When the solution is heated to 60- 80° in 20 minutes, a layer of metal with a thickness of only 1 mm will dissolve. After etching, the part is thoroughly washed with water and polished."
Caustic soda in pure form They are unlikely to sell it to you, but “Mole” consists of caustic soda plus some additives. I used dry "Mole" in a bag.

I made a saturated solution (I filled it with water in a bottle so that the powder did not dissolve completely, but remained at the bottom).

ATTENTION! CAUSED SODIUM IS A VERY DANGEROUS SUBSTANCE! THE PRECAUTIONS ARE WRITTEN ON THE PACKAGE AND I WANT TO WARN THAT IT MAY MELT THE BOTTOM OF THE PLASTIC BOTTLE IF DISSOLVED!
Therefore, it is better to use glassware.

After this, fill the mayonnaise jar one-tenth full and add water to make a “10-15% solution of caustic soda.” I placed the jar in an ice cream bucket, into which I poured boiled water to maintain the temperature of the etching solution at 60-80° C.

Etching occurs with the release of gas bubbles. Using them you can easily control the process. I avoided very violent gas formation, since in this case the toner may peel off, and the etching proceeds, as it seemed to me, very unevenly.
If the reaction proceeds very quickly, then you can either dilute the solution more or lower the temperature.

I didn’t monitor the temperature (I was working on a model), periodically adding hot water from the tap, and in about a couple of hours my plate began to show through. The drawing was not completely etched, but I didn’t wait for it.

That's why I had the following considerations. Firstly, due to lateral etching, the boundaries of the pattern deteriorate. Secondly, the toner did not adhere well, and etching went through it, which was noticeable by the rare bubbles that formed directly on the painted areas.

Taking out the plate, I washed it in hot boiling water.

After that I washed off the toner