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 - one person at the market said that he dips shiny parts in waste from etching 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. The duralumin was slightly worse, but acceptable. 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 this not large quantity 15-20 grams of ferric chloride is enough for parts.

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 carefully coat the inner surfaces of the 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 it is, relatively simple and qualitative method blackening. I hope that it will be useful not only to me, but also to other enthusiasts.

As you know, products made of aluminum and its alloys oxidize quite quickly and unevenly, as a result of which the same homemade body becomes covered with gray spots. This can be avoided by anodizing the surface. As a result, the metal is evenly covered with a passive film, which prevents further oxidation. If desired, the anodized surface can be easily painted with ordinary aniline dye.

In order to carry out anodizing, you don't need anything special. You need baking soda, table salt, water, an aluminum container and a 12 V DC source that provides up to 2 A of current.

To prepare the electrolyte, prepare two solutions - saturated soda and saturated salt. To do this, salt and soda are separately dissolved in boiled water at room temperature. To obtain high-quality saturated solutions, dissolution must be carried out for at least half an hour, periodically adding salt (soda) and stirring. After this, both solutions are left for 15 minutes and filtered.

To prepare the electrolyte you will need 9 parts of soda solution and 1 part of salt solution. All operations are carried out in glass containers.

Before anodizing, the workpiece must be cleaned with fine-grained sandpaper, degreased in a hot solution of any washing powder and washed with running water. After this, you cannot touch the workpiece with your hands. Anodizing is carried out with a current density of 12 mA/cm2. To calculate the total current (in amperes), you will have to calculate the total area of ​​the part (in cm2) and multiply by 0.015.

Anodizing is carried out in an aluminum container, which acts as a negative electrode. The positive pole of the battery is connected to the part through a rheostat set to maximum resistance and immersed in the electrolyte. After this, the current value is brought to the calculated value. The anodizing process lasts about 90 minutes. In this case, the part will be covered with a bluish-gray coating. At the end of the process, the part is removed from the bath and washed in running water with a swab dipped in potassium permanganate. The coating turns out to be an even gray color and, as mentioned above, is easy to paint.

For coloring you will need aniline dye of any color. The dye solution contains 15 g of dye and 1 ml of acetic acid (per 1 liter of water). The solution is heated to 60...80°C. The exposure time depends on the desired color saturation and is controlled visually (usually 5-15 minutes).

Industrial and artisanal method of aluminum anodizing

Anodizing aluminum (anodic oxidation) is a process that results in the formation of an oxide coating on the surface of the metal. The main task of the oxide coating is to protect the surface of aluminum from oxidation that occurs due to the interaction of this metal with air. Anodizing is not intended to destroy the film formed during oxidation (it performs a protective function), but to make it more durable. In this respect, anodizing is similar to a method such as oxidation bluing.

• Anodizing technology
• Preparatory process
• Chemical treatment
• Consolidation
• Other Anodizing Methods
• Preparation of the solution
• Anodizing

Anodic oxidation technology is used to strengthen not only aluminum and its alloys, but also other metals. For example, oxide coatings are used to protect titanium and magnesium.

In addition to strengthening the surface layer, anodizing has the following goals:

• smoothing of various surface defects (chips, scratches, etc.);
• increasing the adhesive qualities of the material (paint adheres much better to the oxide film than to bare metal);
• improvement appearance metal;
• giving the metal various decorative effects (for example, you can create an imitation of gold, silver, pearls).

Anodizing technology

The anodizing process can be divided into three parts:

• preparatory process;
• chemical treatment;
• consolidation

Preparatory process

At this stage, the aluminum profile is subjected to mechanical and electrochemical processing. Mechanical processing refers to metal cleaning, grinding and degreasing. Next, the product is first placed in an alkaline solution for etching, and then transferred to an acid solution for brightening. Preparation is completed by washing the surface. Moreover, washing is carried out several times to completely remove acidic substances from the metal.

Chemical treatment

Chemical oxidation of aluminum is the treatment of metal in an electrolyte. Solutions of various acids (sulfuric, chromic, oxalic, sulfosalicylic) are used as electrolytes. Sometimes salt or organic acid is added to solutions.

The most common electrolyte is sulfuric acid. Yet this electrolyte is not used for processing products of complex shapes that have small holes or gaps. In such cases, chromic acid is preferred. But oxalic acid can significantly improve multi-colored insulating coatings.

Chemical oxidation of aluminum

The quality of the process depends on several components, including concentration, temperature and current density. High temperatures speed up anodization. Moreover, the film formed is soft and highly porous. If a hard coating is required, a lower temperature is used.

Chemical oxidation of aluminum can be carried out at temperatures from zero to plus 50 degrees Celsius. Current density can vary from 1 to 3 Amps per square decimeter. The electrolyte concentration indicator can be in the range of 10-20%.

Consolidation

After oxidation, the metal looks like a porous surface (even when using cold mode). In order for the surface to be strong enough, these pores must be blocked. This is done in one of three ways:

• dipping the product in hot fresh water;
• steam treatment;
• placing the metal in the so-called “cold solution”.

Note! If the product will be painted, the fixing process is not necessary, since the paint material naturally will fill existing pores.

There are three types of equipment for aluminum oxidation:

• basic (baths);
• servicing (providing work);
• auxiliary (feeding products into the bath, preparing, storing, etc.).

Other Anodizing Methods

Besides classic way, described above, hard anodizing, micro-arc and color anodizing can also be used. These methods of metal processing will be briefly discussed below.

The goal of hard anodization is to obtain a particularly strong microfilm. The technique is widely used in aircraft, automotive and construction industries. The peculiarity of the technology is that not one, but several electrolytes are used at once. For example, oxalic, sulfuric, citric, tartaric and boric acids can be used in one process. During anodization, the current density gradually increases, and due to structural changes in the cells, the film acquires increased strength.

Micro-arc oxidation scheme

Microarc oxidation is an electrochemical process in which the surface of aluminum is oxidized, and at the same time electric charging phenomena occur between the anode and the electrolyte. The technique makes it possible to obtain particularly high-quality coatings with a high level of wear resistance and adhesion.

Another method of anodizing is color. As the name suggests, the main task of the process is to change the color of the part.

There are four methods of color anodizing:

1. Coloring by adsorption method. It is carried out by immersing the product in an electrolyte bath. It is also possible to dip the part into a solution with a dye heated to a given temperature.
2. Electrolytic painting (another name is black anodizing). First, a colorless film is obtained, and then the metal is dipped into an acidic saline solution. The final color of the product can vary from black to a faint bronze tint. Black tones of aluminum are especially in demand in the construction industry.
3. Interference staining. The technology is similar to electrolytic dyeing, but due to the creation of a special reflective layer, the color shades are much more varied.
4. Integral coloring. The technology involves mixing an electrolyte with organic salts.

Anodizing at home

Self-anodizing is almost always carried out using the cold method. The majority of companies providing similar services. The cold method is called because there is no need for high temperatures during the film creation process: the operating temperature range ranges between -10 and +10 degrees Celsius.

Advantages of cold anodizing:

1. The surface layer is quite thick due to the fact that the rate of growth and dissolution of the oxide film on its outer and inner sides differs.
2. The film comes out very durable.
3. The treated metal is highly resistant to corrosion.

The only drawback of the technique is the difficulty of further painting the metal with organic-based materials. However, the metal, regardless of its characteristics, in any case receives color naturally. Color can vary from olive to black or grayish.

To carry out the work you will need the following:

• baths (aluminum containers for anodizing, as well as a couple of glass or plastic ones for making solutions);
• aluminum connecting wires;
• 12 Volt voltage source;
• rheostat;
• ammeter.

Preparation of the solution

As mentioned above, the main electrolyte for anodizing is sulfuric acid. However, outside the production premises, the use of such an electrolyte is dangerous. Therefore, at home, soda is usually used.

1. We prepare 2 solutions - soda and salt. We pour the components into containers with distilled warm water in a ratio of 1 to 9.
2. Mix the solution well and let it brew.
3. Pour the solution into another container so that no soda sediment gets into it. The result of anodization largely depends on the purity of the solution.

Anodizing

First of all, you need to prepare the part. The task of the preparatory process is to clean, sand and degrease the surface before anodizing. If visible defects are not removed from the product, the resulting film will not be able to hide them, since its thickness does not exceed 1/20 of a millimeter. Just before anodizing, mix both solutions in one container.

The anodizing container must be large enough to completely immerse the part in it. In addition, the part must be fixed so as not to touch the bottom of the dish. To do this, you can use a stand or any other option - at your personal discretion. You also need to carefully approach the issue of fastening the part, since after anodizing there will be traces in the places of fixation.

The current is applied for at least 30 minutes. The need to complete anodizing is indicated by a change in the color of the part. When the part is ready, turn off the voltage and remove the metal from the bath.

After removal, thoroughly wash the workpiece. To ensure high quality results, place the metal in a manganese solution for 15 minutes. Then we rinse the part again, first in warm and then in cold water. Next, dry the metal. If the technology is not broken, the product will acquire a light gray tone. A well-done job is indicated by a uniform surface color and the absence of drips and stains.

The final stage of anodizing is film consolidation. It is necessary to close the microscopic pores present in the film coating. To do this, put the metal in a container with distilled water and boil for half an hour.

If desired, you can also paint or varnish the metal surface. The paint layer is applied by immersion.

So, anodizing aluminum can be done in different ways. However, only cold metal processing with soda and salt solutions is available at home. It is also worth noting that, subject to technological requirements Regardless of the type of solution, there is no significant difference in the quality of the resulting surfaces.

Anodizing aluminum at home

Every metal needs protection from rust and corrosion, including aluminum, which is very often used by ordinary people at home. If you create a dense and thick oxide film on the surface of aluminum, this will be quite enough to inhibit further corrosion, which is obtained in the process of anodizing aluminum. The most mechanically strong and resistant films are obtained by low-temperature thin-layer anodization of aluminum, which is what you will do.

Security questions

Carrying out high-quality anodizing at home is not difficult. It is safer and more convenient to do this work on the street or balcony. During the process, you will encounter several health hazards.

Acid is a very caustic thing. Although it is in a highly diluted form and causes only mild itching when it comes into contact with the skin, if it gets into the eyes it can cause serious injuries! Therefore, it is advisable to wear safety glasses when anodizing and always have a bucket of water or a weak soda solution on hand.

During the anodizing procedure, oxygen is released at the anode and hydrogen at the cathode. After mixing these gases, they form the well-known explosive gas, which, in principle, is the same as dynamite. Therefore, when anodizing in indoors You can die from the first spark.

Preparatory work

Remember that parts become larger after anodizing. The thickness of the protective anodic layer is usually 0.05 millimeters. For example, threads that were previously tightly tightened will no longer tighten at all after the anodizing process, since in this case the bolt in the nut will become 0.2 millimeters tighter. And it is almost impossible to polish anodized.

It is useful to polish the products to a mirror shine on a polishing wheel. Thus, the aesthetics of the part will greatly benefit and the likelihood of “burnout” during anodizing will be reduced. By the way, the anodic layer does not mask surface defects - they will be noticeable on the processed product.

Before galvanizing, aluminum must be thoroughly degreased. You should not keep the metal in hot caustic sodium or potassium, as is recommended in factory technologies, because the cleanliness of the surface noticeably deteriorates. It is better to use a bar of laundry soap and a toothbrush, because you will be working with small parts. First rinse the product in warm water, then in cold water.

Very effective washing powder: It needs to be dissolved in hot water in a plastic container. Then you should pour the products there and shake the vessel well. After washing, dry the parts thoroughly with hot air. Don’t worry about small traces of fat: after degreasing, you can pick up the product because the layer of fat from your fingers is instantly oxidized by oxygen.

Electrolyte production

The electrolyte for anodizing at home is a solution of sulfuric acid in distilled water. You can also use ordinary tap water, but if you can take distilled water, it is better to choose it, since in the first case the uniformity of the process—the distribution of current density on the surface of the part—is slightly deteriorated.

It’s stupid to make sulfuric acid yourself, but distilled water is very easy! If there is no snow or rain outside, then there will always be ice in the freezer. You can get distilled water and sulfuric acid at your local auto parts store, as these ingredients are used to service car batteries.

However, the acid is sold there in a diluted form to a density of 1.27 grams per cubic centimeter under the name “Electrolyte for a lead battery.” You need to mix this electrolyte with distilled water in a 1:1 ratio.

If you take a standard 5 liter canister of electrolyte and the same amount of water, you will end up with 10 liters of anodizing solution. This is enough for small parts, but for large parts it is worth doubling this amount.

Remember that mixing acid with water will generate a lot of heat. If you pour water into acid, it will instantly boil, splashing in your face! That is why it is recommended to pour the electrolyte into a container of water in a thin stream, stirring constantly with a glass rod. And it's better to wear safety glasses! If acid gets on clothing or skin, rinse it off immediately with a stream of water and rinse with a soda solution.

Processing modes

The temperature of the metal anodizing process is -10 - +10 degrees Celsius. A growing layer below -10 is quite good, but the voltage supplied by the power supply is not enough to maintain the required current. Above +10 degrees, although a protective film will form, it will be soft and colorless.

However, it is recommended to stop the anodizing process already at 5 degrees above zero. But the thing is, in the corner of the bath and on the surface of the part there is a different temperature, and during anodization a lot of energy is released in the form of heat.

But if forced mixing of the electrolyte is not ensured, you cannot trust the thermometer! However, you should constantly stir the electrolyte, with a spoon, with air, or with a pump, this is necessary to equalize the temperature on the surface of the aluminum product. Otherwise, areas of local overheating will form on the part, followed by breakdowns and ripping of the part.

The anode current density should be in the range of 1.6 - 4 Amperes per square decimeter. Within such limits, a beautiful, colored and dense protective anode layer will grow. It is best to maintain a current density of 2 to 2.2 Amperes/dm2. At a lower current, the coating will grow slowly and not thick. At a current greater than 4 Amperes/dm2, an electrical breakdown may occur and the product will quickly become etched.

The cathode current density must be low. The lower this indicator, the better, because this ensures a uniform and soft distribution of current density over the surface of the workpiece, especially if it is large. Therefore, remember that the area of ​​the lead cathode should be twice the area of ​​the part (anode).

The process of anodizing an aluminum profile does not specify the anode-cathode voltage. However, if your circuit has non-zero resistance, then you need a decent voltage power supply. Moreover, it is advisable that you use a power supply with multiple output voltages. And that's why.

The protective layer that grows on the product is a dielectric. As it increases, its electrical resistance constantly increases. To maintain the required current density, the current must be adjusted several times throughout the process using a variable resistor.

However, the voltage may not be enough when the anode layer becomes thick enough. In this case, you need to add voltage. Therefore, the power supply must provide at least two voltages at the output.

Anodizing bath

Before work, it is necessary to prepare equipment for anodizing. Usually several baths are required: for processing small parts, short and long products. They must be made of aluminum. Polyethylene is also a suitable option. Can be used as a small container food container or a long plastic flower pot.

It is advisable to cover the bottom and walls of the plastic bath with aluminum sheets. You can cut a pattern from a sheet of aluminum and bend an improvised “container”. The point of this is to ensure uniform current density on all sides of the product.

The bath must have good thermal insulation of the body, otherwise the electrolyte in it will heat up too quickly and will have to be changed more often. The simplest solution would be to cover the bathtub with a thick layer of polystyrene foam - 2-4 centimeters. You can also secure the bathtub inside the box and fill the gap with construction foam.

After this, a lead cathode should be made for the bath. It can be made from sheet lead by removing the latter from thick electrical cables. Let us recall that the cathode area should be twice the surface area of ​​the workpiece. This does not take into account the surface of the cathode, which is leaning against the wall. The cathode plate must have holes for gas outlet.

You can build a cathode from several pieces of lead if you don't have one. It is recommended to solder the pieces with a powerful soldering iron, with a thick seam along the joints. Try to ensure that the cathode follows the surface configuration of the part facing it. Remove the contact from the bath using a strip of the same material. Although it is also common to use thick copper wire in insulation. Insulate the soldering area with silicone sealant.

Anodizing process

So, you have poured electrolyte into a plastic bath, and at the output there is a power supply with current. To regulate the current in the circuit when anodizing titanium or aluminum, connect a wirewound variable resistor. There are 2 items in the container: a lead cathode in the form of a plate and an anode - the product being processed. When current is applied to them, oxygen is released and the anodic protective layer begins to grow.

When creating quality electrical contact between the lead and the part you will observe oxygen microbubbles that slowly rise from the entire surface of the product. Their diameter is extremely small, their flow resembles wisps of smoke. The duration of the process should be controlled visually - by the color of the part.

For small parts it takes 20-30 minutes, for large items - an hour and a half.
After the part is completely covered with a gray-blue coating, it should be removed from the bathroom, washed under running cold water and wiped with a cotton swab dipped in a strong manganese solution to remove reaction by-products. The surface should be shiny, light gray, smooth.

After the anodizing process at home, some products acquire a dark matte shade, it all depends on the anodizing mode. To paint anodized products, immerse them in a solution of aniline dye, which is heated to 50-60 degrees Celsius. Before work, filter the solution, because small grains of undissolved dye can form stains on the metal surface. The color intensity usually lasts no more than 15-20 minutes.

After the part has acquired a beautiful shade and a hard, not loose protective layer, it is necessary to fix it. The fact is that this coating at the micro level has a porous structure that is permeable to air and water. This metal layer protects well from mechanical damage, but is weak against chemical damage.

There are several methods that help close micropores. The simplest is to boil the parts in a pan in water for half an hour after anodizing. It is better to use distilled water. Also, the parts can be kept in a steam bath, also for half an hour.

You already know that there are several technologies for anodizing aluminum and parts made from it. They differ in the working process conditions, and more specifically, in the temperature of the electrolyte, which is the main factor that affects the quality of the anodic protective layer. At home, it is preferable to choose the option of cold anodizing, because in this case the coating is of higher quality and thicker, and the part acquires a beautiful shade and shine.

Articles on the topic

A question arose: aluminum parts are available, anodized and painted green, I don’t like this color, is it possible to repaint them again using an aniline dye without removing the anodized coating, or if you remove the anodizing in alkali, will the anodized aluminum be painted in the dye?
I want to paint it black or dark gray

The green color that burns on the “khaki” is a hard anode. Very durable and wear-resistant coating. This is not specially painted - it is the natural color of the hard anode crust.

The “green” surface on duralumin is not yet a hard coating, the main purpose is still protection against corrosion. The film is gray in color; filling the pores with chromium creates a greenish-yellow color. You can increase the hardness of the coating (of any color!) by carrying out anodic etching at low temperatures (!) - (9-16 degrees C!) Surface hardness corresponds to sapphire (!) Any coloring of the anodic film (before closing the pores!) is very durable and does not fade! If it burns out or is erased from the surface, then this is a violation of the regime or other errors! When the anodic film is formed, the surface “grows” - the geometric parameters of the parts change slightly; if exact dimensions are required, this must be taken into account! Compared to chemical painting, anodizing is much thicker and stronger (more durable).
About 30 years ago, I anodized the parts of the boss (D16t) black, painted with “wool dye” (aqueous solution...)

You can anodize two parts at once using alternating current.

ABOUT!
How's that? Here it already smacks of the Nobel Prize, on the “variable”
That is, one ion sticks to one part, the other to another?
And the first one (at this time) - what is he doing? If it's not a secret, of course...
But seriously: anodizing is a rather capricious process and difficult to implement at home.
Much easier - powder coating. It takes ten minutes, the color and texture of the surface is any (from the available paints).
The strength of the coating is amazing; it is difficult to file with a file.
True, you need a paint gun with static and paint. But there are plenty of companies that paint to order.

Yes WELL! No need to complicate things! The process is quite simple and reliable... It was shown to be simple, but the bells and whistles with the power supply and the unpresentable appearance of a canister of acid and “pieces of lead cable” put people off... Gases and acid fog are no more than when charging a car battery! DiMa72 - well done! I took it and did it! Old proverb: Port wine doesn’t flow under a lying stone - it works here... Just don’t be lazy... - It’s not the gods - they anodize duralumin.)
Yes, by the way, I did it right right away: the suspension is aluminum wire, the rest is stainless steel, and all this in 800g. glass jar, put ice around it to cool it down.

WORLD OF HOBBIES

Aluminum and its alloys, like copper (and its alloys), can also be oxidized, and chemical coloring of aluminum produces colors ranging from yellow to brown.

Reference table of approximate colors obtained on the surface of aluminum using various processing methods.

Solutions for oxidation of aluminum and its alloys:

Soda ash - 40-50 g/l, sodium chromate - 10-15 g/l, sodium hydroxide- 2-2.5 g/l. Solution temperature - 80-100°, processing time - 3-20 minutes.

After washing, the part is immersed for 10-15 s in a 2% solution of chromic anhydride.

Chromic anhydride - 3-3.5 g/l, sodium fluorosilicate - 3-3.5 g/l. The solution temperature is 15-25°, the processing time is 8-10 minutes.

Orthophosphoric acid - 40-50 g/l, potassium fluoride - 3-5 g/l, chromic anhydride - 5-7 g/l. Solution temperature - 15-25°, processing time - 5-7 minutes.

Sodium dichromate - 200 g/l, hydrofluoric acid- 1-2 ml/l. The solution temperature is 15-25°, the processing time is 6-10 minutes.

When using the last recipe on an aluminum part, a beautiful rainbow color with a dark haze is obtained.

The so-called chromate oxidation of aluminum and its alloys with an internal source of electric current is also possible. The aluminum part is securely connected by a conductor to a carbon electrode (a carbon rod from a flashlight battery, a Saturn battery, etc.). Both electrodes, connected by a conductor, are immersed in a solution of the following composition:

Nitric acid- 200 ml/l, potassium chromium - 50 g/l. Solution temperature - 15-25°, processing time - 2-10 minutes.

Chemical coloring of aluminum at home can be done as follows

way. Aluminum is coated with some metal (for example, nickel, silver), which is chemically painted to the desired color. It is known that aluminum is easiest to coat with zinc, which can be painted in dense black and yellow-green colors. Aluminum can be painted in a permanent black color as follows. After zincate treatment, the part is placed in a solution: Copper sulfate - 160-220 G/l, potassium chlorate - 80 g/l. Solution temperature - 30-40°, processing time - 5-10 minutes.
Zinc-coated aluminum is painted yellow-green using the following solution:

Potassium chromium- 200 g/l, sulfuric acid- 5 g/l. Solution temperature - 15-25°, processing time - 1-2 minutes.

A wide range of colors can be obtained by anodizing aluminum using electric current. The anodizing process typically involves the use of direct current. But in Lately An AC anodizing method has been developed that is also suitable for home use. All equipment consists of a transformer Tr, the output of which should be 12-15 V, an ammeter with a scale of 3-5 A and a rheostat R = 30-100 Ohm for adjusting the current (Fig. 12).

Two parts (or two groups of parts) are prepared and suspended in a bath (jar, bowl, etc.) for anodizing. The container should be glass, porcelain or enamel. The parts are securely connected with aluminum wire. The electrolyte is a 15-20% solution sulfur acid or sodium bisulfate solution (crystalline) concentration 250-400 g/l. The current density (ammeter reading) should be 1.2-2 A for each square decimeter of part area, voltage 10-12 V. Electrolyte temperature is not higher than 25°, anodizing time 30-35 minutes.

For duralumin, the current density should be about 2-3 A/dm2. voltage - 12-15 V. Electrolyte temperature 20°, anodizing time - about 25 minutes.

After anodizing, a colorless film several micrometers thick with a large number of small pores is formed. The final processes in anodizing are coloring and closing the pores. Dyeing is done using aniline wool dyes (sold in hardware stores). Concentration of paint in water is 1%, color of your choice. The paint is dissolved in water, filtered, heated to a temperature of 70-80°, the part is kept in it for 2-3 minutes. The part can be painted in any color, but the most impressive is painting anodized aluminum in gold. Anodized aluminum can be painted to look yellow gold using a solution:

Acid orange dye 2ZH - 0.1 g/l, acid yellow dye 3 - 0.1 g/l, acid black dye M - 0.1 g/l. The solution temperature is 17-20°, staining time is 5-7 minutes.

Anodized aluminum to look like red gold is painted with a solution:

Acid orange dye 2Zh - 0.1 g/l, acid black dye M - 0.1 g/l. Solution temperature - 60°, staining time - 5 minutes.

A golden color can be obtained by dipping the anodized part in a 10% solution potassium chromium for 10-20 min. The solution temperature is 85-90°.

Another lineup. It allows, depending on the exposure time, to obtain colors from light golden to dark bronze.

Ferrous ammonium alum - 28 g/l, oxalic acid - 22 g/l, ammonia(25%) - 27 g/l. Solution temperature - 50-60°, staining time - 2-5 minutes.

After painting the anodized aluminum, the final process is to close the pores. It's very simple. The part is placed in boiling water and kept for 15-20 minutes.

Perhaps, every home will certainly have some little thing or product made of aluminum that has already lost its presentable appearance, but you would really like to return it to its former beauty with the always attractive appearance of antiquity. How then? We suggest you do patination of aluminum at home yourself, without resorting to professional help specialists. Let's look at this process in more detail so that you have a clear idea of ​​what you have to do.
Is it difficult?
Most often, “aging” aluminum products is practically no more difficult, and sometimes not even easier, than other metals. And all just because aluminum perfectly accepts all kinds of color tones during electrochemical oxidation, or, in other words, anodizing. As a result, a special film is formed on the surface of such a product, preventing the occurrence of metal corrosion, thereby imparting aesthetic charm. finished product.
If you consider this method too complicated for you, then you can use simpler ones, for example, the most ordinary ink for drawing, black alcohol-based varnish or finely crushed graphite and other specialized coloring agents. After such methods, you just need to wipe the “aged” trinket with kerosene.
A simple patination method
After reading all the above methods, you still couldn’t choose how best to “age” your new aluminum product, then quickly read this simple method that allows you to patina aluminum at home, using simple improvised means that cost literally pennies .
To do this, you will need to carefully wipe the finished aluminum item with a small piece of cloth soaked in acetone to remove all possible “greasy” stains or stubborn dirt that are on the surface. After everything is cleaned and thoroughly dried, you will definitely need to moisten the product with some solvent, for example, White Spirit or any other that you can find at home or buy at a hardware store. Then burn the workpiece with a blowtorch.
But, remember! The more solvent you use directly on the product itself, the darker the patina will subsequently appear as a result of its combustion on the surface under the influence of a blowtorch. If you want to get barely noticeable traces of darkening, then it is best to apply the solvent using a brush with coarse bristles.
And in order to obtain a very dark shade, the product must be placed completely directly in the solvent. In this case, in convex places it will be necessary to remove its excess so that small accumulations of the substance remain in the recesses. When working in this way, the product is placed in a horizontal position so that the solvent does not flow where it is not needed. You will need to burn with a blowtorch for several minutes, moving the fire evenly to avoid excessive overheating, which could simply melt your aluminum product.
After the product has completely cooled, you will also need to carefully lighten its convex parts. To do this, you will need to wipe them with a cotton pad soaked in oil for lubricating a sewing machine, to which the smallest shavings of abrasive powder have been added. Then wipe dry with a clean, dry cloth to remove all abrasive residue. The type and duration of the effect from this method, which allows you to patina aluminum at home, is no worse than from chemical methods. And most importantly, it is much safer - you will not be harmed by acid.
Let's sum it up
Aluminum is a metal with remarkable plastic qualities, which is very convenient to use in creating various decorative parts of the interior. But sometimes you want to replace the novelty of such products with an “antique” that is pleasing to the eye. And we learned how to do this from this article - patination of aluminum at home.

Each of us has come across such a definition as anodizing, which applies, in particular, to aluminum products. This metal in its pure form or its alloys are well suited for making various crafts, which is used by many home craftsmen. The metal is light in weight, has high strength and is easy to process. But most importantly, it is resistant to corrosion. Many craftsmen carry out this at home.

But why is this done, since the material itself is quite durable and looks good? However, despite all the advantages, it also has weak sides. And him main drawback- this is interaction with air, resulting in an oxidation reaction. This leads to the formation of plaque, which significantly complicates the painting of products. In addition, the type of aluminum itself is far from perfect. It is for this reason that aluminum undergoes an anodizing procedure.

What is anodizing?

According to GOST standards, anodizing is called anodic oxidation. The main result of the electrochemical process of aluminum anodization is the formation of a more durable oxide coating.

The fact is that during the oxidation of the metal, a protective film is formed on its surface, which is easily damaged. The whole point of anodizing is to strengthen this film, and not to apply any coating, which usually happens when chrome or galvanizing products. The film is formed from aluminum itself.

The process is very similar to another technology - bluing. Not only aluminum products are subjected to anodization; magnesium and titanium are also, if necessary, subjected to such a protective treatment.

The need for anodization and its methods

What can anodizing aluminum do for metal at home? First of all, the ability to resist corrosion will increase significantly. A stronger oxide protective film will last a very long time and will not peel off.

In addition, there are a number of advantages that anodic oxidation technology provides:

• Smoothes the surface of aluminum products, that is, hides some defects (scratches and pinhole damage, chips, stripes) and makes the metal uniform.
• Paint coatings adhere better to such metal due to the acquisition of a matte surface.
• profiles have improved protective properties.
gives the metal more attractive features.
• Large thickness protective film.
• Possibility for various imitation - silver, gold, pearls, etc.

When it comes to aniline dyes, there are many options. In addition, anodizing can be performed in different ways:

• cold;
• hard;
• colored.

Let's look at them briefly below.

Cold anodizing

At home, the cold method of anodizing aluminum is often used. Many companies that offer services in this area also mainly specialize in this method. The operating temperature range is from -10 to +10 degrees, which is why the technique is called cold.

Among the advantages of anodizing aluminum at home using this method is the production of a thicker protective coating, which increases resistance to corrosion.

Only processed products are difficult to process with organic paint materials. Although the metal will acquire color in any case, and the shade can be olive, grayish or black.

Hard Anodizing

The result of solid anodic oxidation is a particularly strong protective film. Largely due to this, this technology is successfully used on a huge scale:

• industry;
• aircraft manufacturing;
• automotive industry;
• construction.

A feature of hard anodizing of aluminum is the use of several electrolytes at once. In addition to the use of sulfuric acid, a number of other analogs are also involved: oxalic, sulfuric, citric, tartaric and boric. And this is only during one process in which the current density gradually increases.

The strength of the protective coating is increased due to structural changes.

Color anodizing

The essence of this method is to change the color of the metal. In this case, 4 main methods can be distinguished:

1. Adsorption - products are immersed in a special bath or in a dye solution heated to the required temperature.
2. Electrolytic (black anodizing of aluminum) - initially a colorless film is obtained, after which the aluminum products are dipped into an acidic saline solution. Black is a common color used in construction, but a slightly bronzed tint can also be achieved.
3. Interference - the technique is similar to electrolytic, but in this case a special reflective layer is created, due to which the color palette is much larger.
4. Integral - the essence of this method is to mix the electrolyte and organic salts.

As you can understand, color anodic oxidation allows you to acquire a new shade of color, depending on your preferences.

Home technology

In industry, anodizing of metals is carried out using sulfuric acid, but anodizing aluminum at home using it is extremely undesirable due to the release of a large amount of gas. Once the slightest spark is formed, sad consequences cannot be avoided. The technique itself remains unchanged, but soda is used instead of acid.

But first you should prepare the “equipment”:

• several baths;
• wiring;
• Battery or rectifier (current source);
• rheostat;
• ammeter.

Aluminum containers are needed directly for the process itself. The other two are needed for preparing solutions, for which glass or plastic products are useful.

Preparation of an alternative electrolyte

To prepare solutions for anodizing aluminum with your own hands (soda and salt), you only need warm distilled water. The components for mixing are kept in a ratio of 1 to 9 (soda or salt - water).

The solutions are mixed well, after which they need to brew. And after some time, they need to be poured into other containers, and try to prevent the ingress of soda sediment. The final result of the procedure will depend on the purity of the solution.

Before the part is processed, it must be cleaned, if necessary, the surface must be sanded and degreased. The film thickness is no more than 0.05 millimeters, so it cannot hide visible defects.

Immediately before the process, you need to mix the prepared solutions in one container.

Electrochemical process

The container in which anodizing will be carried out must completely contain the product being processed. At the same time, it should not touch the bottom of the container. Any of the convenient options is appropriate here, you just need to be smart. The fastening of the part also needs to be carefully thought out, as this may leave traces that ideally should not exist.

According to aluminum anodizing technology, the power source is connected as follows: “plus” is supplied to the part, and “minus” is supplied to the bath. The duration of the procedure is at least 30 minutes. A change in color of the product will indicate the end of the process. You can disconnect the battery (usually it is used more often) and remove the part.

The treated product is washed well, and to get rid of the remaining solution, you can keep it in potassium permanganate for some time. Afterwards, you need to rinse it again in cold and warm water (alternately) and dry it. With the right approach, the part will be distinguished by a light gray tint, evenly covered over the entire surface. There should be no stains, streaks or drips.

Final stage

It is necessary to complete the procedure, since the resulting film is characterized by the presence of micropores that are not beneficial. They need to be closed, for which the part must be boiled in distilled water for half an hour.

Upon completion and if desired, the part can be painted or coated with clear varnish. Although the metal acquires a natural color during the process, which depends on the composition of the part being processed. Typically the shades can range from green to dark, but the result is often anodized black aluminum. To give the part another desired color, the part is immersed in a solution with aniline dyes (10%).

As you can see, anodizing aluminum can be done at home, but of all the methods, only cold method, since it is more secure. In addition, there is practically no difference between the type of solution (soda or acid); the result will be the same in any case. The main thing is to follow the instructions.

zloyqadrat 04-10-2010 20:00

I came across a simple way to blue aluminum
http://rekomstroy.ru/uslugi/decorativnoe_pocritie_metallov.html
"Black mordant for aluminum
.
The surface of an aluminum object is first polished with the finest emery powder, then greased with olive oil and heated, with frequent lubrication with this oil, over an alcohol lamp until the olive oil turns black. After this, the heating is stopped and after the object has cooled, wipe off the oil with a rag."

Has anyone tried bluing like this?

Gaydamak 04-10-2010 21:55

But refined or not? What about sunflower? What if it’s not an alcohol lamp, but a gas burner?

Stop163 04-10-2010 22:18

I'll check in. interested

Alex*D 04-10-2010 22:42

Look at the bottom of the pan.....
The oil burns - what remains is coal....

Demonos 04-10-2010 23:02

Olive oil is not a mordant, but rather a seasoning.
I have heard many times about bluing heated steel in oil. It never worked out. And I have never seen high-quality coverage. On the other hand, aluminum cannot be coated with anything other than anodizing. Maybe it will roll.

docentus 05-10-2010 12:07

Well...
What kind of aluminum parts do we have in pneumatic construction?
Boxes, mods, some little things, this is what I know.
But it’s unlikely that anyone would want to cover a box, or something similar, with such a coating. I definitely wouldn’t, it looks more like smoking, with a corresponding crappy appearance.
Convince me - give me photos of high-quality blackened aluminum parts filled with burnt oil. Really want to.

docentus 05-10-2010 12:11

Nik G 05-10-2010 03:48

For aluminum I saw a primer in a can at the auto store. You can already use paint on it. This is according to the seller.

Maloros 05-10-2010 10:28

quote: over an alcohol lamp until the olive oil turns black.

Basil_84 05-10-2010 11:05

Household Rub soap rather to determine the temperature.
Because holidays are made even without soap.
http://sovet.bos.ru/html/oadiedaneaij_iadaaioea_iaoaeei.html

Maloros 05-10-2010 11:20

quote: Household Rub soap rather to determine the temperature.

P_L_Z 05-10-2010 11:28

intrigued

Fake 05-10-2010 12:51

I did something similar.
Ink moder pipe.
The Leroy pipe 25x1.5 has already been somehow treated on the outside, with a matte surface.
I rubbed it with a thin layer of oil, just to make it shine. Then he carefully smoked it over a candle. The final result depends on the quality of this smoking. "Fringe" should not be allowed. After smoking the entire pipe, he heated it on gas until the oil burned out. Then again rubbing with oil and smoking. Do this three times.
Then he rubbed it with butter and let it cool. Then I washed it under the tap with soap and used it.
The coating itself does not peel off, but can also be scraped off with hard objects.

It was not possible to coat the turned moder plugs in this way. But there was also an end from under the cutter. I didn't bother with sanding. I left the cork white.

PS I took the first oil I found. It turned out to be olive. I haven’t tested it with sunflower.

Kaynin 05-10-2010 13:05

funny topic.

black - from charring.

Fake 05-10-2010 15:03

funny topic.

in fact, heated oil is drying oil.
black - from charring.

analogue - black oil paint on natural drying oil with high temperature drying.

In my case, it was the soot that gave the light. The oil was only used as a binder.
What happens to the oil when it is heated above the uh... "smoking" temperature is a mystery to me. It becomes something like varnish.

I tried mixing soot in the same oil. It was not possible to apply a thin layer evenly.

Kaynin 05-10-2010 15:14

quote: Originally posted by Fake:
In my case, it was the soot that gave the light. The oil was only used as a binder...

MadMaks 05-10-2010 20:23

quote:
Demonos posted 4-10-2010 23:02 I have heard many times about bluing heated steel in oil. It never worked out.

Demonos 05-10-2010 20:26

So it’s not a mordant. It's paint. It was a sin that I thought that the oil might produce some kind of acid, or a salt that produces black oxide with aluminum.

RICCI 05-10-2010 20:54

An alcohol lamp does not smoke; anyway, you won’t know until you try.

RICCI 06-10-2010 08:47

Some kind of dye may be produced in the hot oil, which penetrates into the lumine.

Alter 06-10-2010 11:13

I tried it too, but it’s not suitable for frequent hand waving.
There is a way with *gun varnish*. I haven’t tried it myself, but if anyone does it will be the first passer
The recipe is BF-2 (or BF-4) glue. Nigrosin. Alcohol. Alcohol is not ingested.
The components are mixed and applied to the product and either aluminum or steel. It’s baked in the oven, I don’t know how long, how many layers, too, but for glue like BF, an hour is enough.
Or in another way - bakelite varnish (a component of BF), ballpoint pen paste (nigrosin), alcohol (alcohol).

RICCI 06-10-2010 14:33

Baking probably won’t work; heat treatment is contraindicated for parts subject to pressure and wear.

Alter 06-10-2010 15:59

quote: Originally posted by RICCI:

heat treatment is contraindicated

major 0763 06-10-2010 17:45

I've been doing this for a long time - crow in oil. anyone.
you do this - heat it up - and add it to the oil. You take it out and heat it with a gas burner until the oil burns out. then again in oil - 30 times. The coating is durable. can only be removed with metal.
and here the trammel-aluminum is still soft and scratches easily. nevertheless, the eight has been standing for six months - it’s normal

RICCI 06-10-2010 18:15

That's it, this is both a rubber and a box made of duralumin, but to what extent should it be heated? more details please.

UZ Mergan 06-10-2010 19:23

Was the sight blued or something?

major 0763 08-10-2010 04:24

No. Only the eight is covered. There is probably no need to heat the rubber.
Heated it so that the oil began to sizzle after dipping. then you take it out and heat it until the oil burns out. There is no need to heat it further - just dip it right away. at least 30 times.
At first there will be brown stains, then they will get darker and darker.

Demonos 08-10-2010 08:20

Need to try. After soldering aluminum from the fixing copper wire in varnish insulation, brown stripes remained on the muzzle. It ate deep. But he also raised the temperature, let’s say, above the combustion temperature of carbon. Based on the disappearance of soot from the product
Here I am again falling for the divinely simple method with fire and oil.

Fake 08-10-2010 09:33

quote: Originally posted by Demonos:

How can you assess whether the oil on aluminum has burnt out? Like “it doesn’t smoke anymore”? Aluminum is not released?

Fake 09-10-2010 12:17

I tried it now on the mod's duralumin partition. One olive oil is enough. Warmed it up on gas. I didn’t put it in the oil, I wiped it with an oiled swab. Thin layer. After the third pass, the entire surface is guaranteed to be black. Made five passes.
I noticed a couple of features.

When oiling, do not allow the oil to boil on the surface. It turns out to be a “bump”, which then flies around and exposes the metal. You have to constantly wipe the surface, creating a thin layer that begins to smoke.

You shouldn't overheat it either. Heated it for about five seconds, took it away from the fire - if it smokes, then heat it further, it stops smoking - oiling.

After the last heating, you cannot cool it with water - the water will boil and tear off the coating. Air cooling only.

As stated above, the coating is not particularly resistant to mechanical stress and is much inferior in strength to anox, but IMHO it is suitable as a collective farm coating for mock-ups.

Marniftarr 09-10-2010 12:53

Gentlemen, all this is good, but oxides do not have the strength of fur. They are good on a production scale. For your beloved rat you need high-quality technology.

As a result, the rats acquired this appearance:

First photo in the topic

I tried to apply this varnish on steel that had just been chemically peeled. The coating remains black, steel in appearance, but durable under the influence of this varnish. In general, if anyone has a spray gun, a compressor and experience working with paints, I highly recommend it. Well, if you can’t get such a varnish, you can use two-component Duxone car paint. By the way, if there is a matte color, this paint can be painted as a powder. Its fur properties resemble epoxy.
Unfortunately, oxides are not stable :-(

Fake 09-10-2010 13:33

Having suffered with oxides, I adopted ceramic varnish.
It is so durable (more wear-resistant than ceramics) that it cannot be sanded or polished after 2 days after application.. therefore, you can use the edge of a knife and the coating will not damage anything.. ... Another feature is that scratches on it self-heal after a few days. ...

Marniftarr 09-10-2010 13:40

It gets scratches from prolonged mechanical impact or from very sharp objects. Even so, this is a material of earthly origin :-) But the scratches are then healed, but not completely. It is impossible to polish such scratches. To polish this varnish after final polymerization, diamond abrasives and a very powerful tool are used.

If the varnish layer is thick, it will adhere perfectly to aluminum. If it is thin, it will probably break due to chips. The varnish is quite flexible, it is resistant to abrasion but is susceptible to breaking and chipping. Therefore, it is better to apply it in a thick layer on polished surfaces.
If the surface needs to be filled, then you need to sand it well with coarse sandpaper, apply primer, base (the paint itself) and then varnish. I did not prime.. I only applied the base, and then applied this varnish in a thick layer.
There are also hemorrhages when applying it - any flaw in painting, be it a speck of dust or snot, cannot be corrected.. If anything happens, the part is immediately thrown into acetone, all the varnish and base are washed off and everything is painted again. It will be impossible to correct something later.. If you don’t wash the spray gun within two hours, you can throw it away.. I’m tired of using this varnish. But the result is worth it.

Demonos 10-10-2010 21:59

quote: I'm exhausted with this polish. But the result is worth it.

Marniftarr 11-10-2010 11:57

Unfortunately, there’s no price:-(The one that my friends gave me for testing has already run out... They gave me 100 grams... And it’s a toad’s toad to give 5 rubles for a lit. with requests and bows, pour a hundred grams..

Kaynin 11-10-2010 12:12

quote: Originally posted by Marniftarr:
Gentlemen, all this is good, but oxides do not have the strength of fur.

Another thing is that the continuity and thickness of the resulting film (and, accordingly, hardness, wear resistance, etc.) depends on the parameters of the anodizing process :-)

Fake 11-10-2010 13:43

By the way, to the heap. I tried refined sunflower oil. More approaches are required and the coating turns out worse, with brown spots.
Motor synthetics only stink strongly and do not provide color. True, I only tried it once, it stinks very much.

Marniftarr 11-10-2010 23:07

quote: Originally posted by Kainin:

By the way, during anodic oxidation (anodizing) of aluminum, this same oxide is formed on its surface

Yes, yes... but who will make galvanized solutions at home in order to anodize them once? And despite the fact that you still won’t get rid of scratches...?!!?!

Kaynin 11-10-2010 23:24

quote: Originally posted by Marniftarr:
Yes, yes... but who will make galvanized solutions at home in order to anodize them once? And despite the fact that you still won’t get rid of scratches...?!!?!

Anox hard (that’s the term) doesn’t work with a regular needle file.
You said - “there is no strength.”

Now you also don’t like “fencing solutions”.

Marniftarr 15-10-2010 12:28

quote: Originally posted by Kainin:

But with your varnish, which is also difficult to get, it’s easier to paint, or what?

Well, how can I say - it’s not simpler... They don’t give you the second 100 grams for testing :-) I’ll switch to epoxy two-component varnishes..

quote: Originally posted by Kainin:

Anox is hard (that’s the term) and a regular needle file won’t take it. You said, “there’s no strength”

about anox. Trigger. Aluminum. Not covered with paint. looks like a glossy black crust. The manufacturer stated that the coating is anox. It doesn't "scratch" with your nails... It doesn't feel like polymer to the touch. It doesn’t prick.. It can be ground down with a needle file without any problems.. Is it Anox?

Demonos 15-10-2010 12:31

quote: Is this Anox?

Alter 15-10-2010 08:47

quote: Originally posted by Marniftarr:

It doesn't "scratch" with your nails... It doesn't feel like polymer to the touch. It doesn’t prick.. It can be ground down with a needle file without any problems.. Is it Anox?