Noble black color or smoky blue is the calling card of one of the quite popular methods of painting metals called bluing (or blackening of metal). In addition to giving a more acceptable aesthetic appearance, bluing the surface of a metal product guarantees a high degree of protection from the negative influence of external factors, in fact it is a kind of protective coating. The process uses various acids and oils. Depending on the selected components of the mixture, as well as on the degree of heating, the shade that the metal will acquire will depend.

Many people mistakenly believe that bluing is an exclusively factory processing option and that it will not be possible to reproduce it in your garage. But blueing metal at home is still possible. By following a certain sequence of actions using the necessary components, such a process can be organized independently. You do not need complex equipment, because steel blackening can be done in much simpler ways.
Such bluing, of course, cannot be compared with factory oxidation, but nevertheless this treatment is quite successfully used in practice and is popular among craftsmen.

Features of metal bluing

In large-scale industrial production, burnishing of products occurs due to changes in the structural composition of the top layer of metal. A coating applied in this way provides reliable protection against corrosion for many years.
At home, it is almost impossible to repeat the methods that are used in industry, and it is not profitable from an economic point of view. Both hot and cold bluing are done by applying a special chemical solution to the surface of the product, which forms a thin oxide film.
You can make a product for bluing at home by purchasing all the necessary components yourself, but you can also purchase a ready-made one at a forging store. For example, sodium nitrate, phosphoric acid, or regular machine oil do a good job. Perhaps the most popular method of blackening metal at home is chemical oxidation. The final result (what color the metal will acquire) largely depends on the choice of method, the quality of all components and how correctly the solution was prepared.

Basic processing rules

In fact, bluing is a chemical treatment of the metal surface, so this process is considered very harmful and even life-threatening. When performing bluing, you must follow a number of rules, such as:

• Before starting work, it is recommended to study in detail the properties of all reagents used in bluing, as well as draw up a clear procedure;
• Use a special container, it can be glass, porcelain or earthenware. Containers made from other materials will simply be corroded by acid;
• All work must be carried out in a room that has excellent ventilation (preferably outdoors);
• As a material for surface treatment of metal, you can use sandpaper of varying degrees of hardness or powdered pumice. Metal brushes can leave very noticeable marks in the form of scratches on the surface of the product;
• Availability of eye, respiratory and skin protection;
• Before starting work, the surface of the product must be degreased and cleaned of debris and dirt.

Alkaline method

In an alkaline environment, bluing is carried out with the addition of oxidizing agents at a temperature of 130 to 150C. This method is based on the creation of an oxide film by oxidation of iron. In this case, you can use a stainless steel vessel to boil the solution.
To prepare the solution, you need to add a little sodium nitrate and 100 grams of technical soda to 100 ml of ordinary water. Mix all components thoroughly, the resulting mixture must be heated to a temperature of 130-150C, and then immerse the workpiece in it for about 25-30 minutes.

Note!
A boiling lye solution emits a very unpleasant odor that can cause dizziness and vomiting. It is advisable to work in a well-ventilated area or outdoors.

Acid bluing

Acid bluing is the process of imparting an oxide film to metal by immersion in an acidic environment. It is performed both chemically and electrolytically. This method allows you to make the surface even and smooth without spending a large amount of money.
To prepare the solution, add 2 grams of tannic and tartaric acid to 1 liter of water and mix thoroughly. This liquid must be prepared in a porcelain or ceramic container. The workpiece is immersed in the solution for 15-20 minutes, after soaking, it is thoroughly washed with running water, wiped and dried.
This method is used for steel, copper and cast iron products. But hardened and heat-resistant products should not be blackened in this way.

Application of rust varnish

Rusty varnish is a composition that causes accelerated rusting of metal, while magnetic iron oxide forms on the surface. If we talk about the financial side of the issue, then the costs in this case will be minimal.
In order to prepare the solution, you need to add 100 ml of hydrochloric acid, 140 ml of nitric acid, 80 grams of iron filings (can be cast iron), 300 grams of crushed iron scale to 2 liters of water. The workpiece is completely immersed in the chemical, resulting in the formation of black or red iron oxide on its surface. Such cold bluing gives a fairly effective and long-lasting result.

Thermal bluing

Thermal bluing of metal is the oldest and at the same time the simplest technology. The essence of such processing is to heat the product (workpiece) to a temperature when the oxygen contained in the air does not begin to enter into a chemical reaction with the upper layers of the part. The more the metal heats up, the darker and richer the shade it will eventually acquire, all due to the fact that the oxidation process occurs at different depths at different degrees of heating.
Literally anyone can carry out such bluing of metal at home, because this does not require any specific components or additional cash costs.

Knife bluing process

The high-carbon steel from which good knives are made can oxidize quite strongly even from quite ordinary household tasks, for example, after cutting vegetables or fruits, if they get into water, etc. The safest and most effective way to burnish a knife is a technology based on a solution of nitrate.

1. Degrease the knife; to do this, simply wipe its surface thoroughly with regular alcohol (or vodka). Alternatively, you can use a 30% alkaline solution for degreasing
2. Prepare a solution of nitrate. Pour 1 liter of water into a stainless steel container, add a little sodium nitrate and caustic soda, mix thoroughly and bring until completely dissolved. This mixture has a strong pungent odor, so it is advisable to work outdoors; if this is not possible, then do not forget to use protective equipment in the form of glasses and a respirator.
3. Place the finished solution in a steam bath, this will prevent it from boiling since the boiling point of such a liquid is higher than that of ordinary water and is about 140C;
4. Place the knife in the solution and leave the container for 80-90 minutes without removing the container from the heat;
5. Upon completion of the process, remove the knife from the solution, let it cool, and then rinse thoroughly with running water.

The main advantage of this method of bluing knives is its simplicity and low cost. After the procedure, the metal surface acquires a pleasant black color, sometimes with a bluish tint.

Other bluing methods

Pencil for bluing. A pencil (marker) for bluing is often used both to restore individual damaged areas of a product, and to apply blackening to the entire surface. If the technology is followed correctly, this type of coating gives the flock a smooth and even appearance. The next step is to paint over the cleaned surface with a pencil. The chemical reagent penetrates quite deeply into the steel, achieving a fairly durable black bluing that can last quite a long time. Finally, wipe the product with a felt cloth or a special tip that is already on the pencil (marker).

This bluing gives a rather uneven color, so it is suitable not for improving the appearance, but for protecting the surface from the effects of negative external factors. It certainly won't rust!

Oil bluing. This processing method is excellent for blackening at home. To work, you will need a metal container of the required size, regular machine oil from 500 ml to 1 liter and a gas burner (any other heating element of sufficient power), paper napkins, bricks or another non-flammable surface. Also, if you are not a motorist and you don’t have car oil on hand, then gun oil, linseed oil and even olive oil will do the job well.

The oil bluing process itself looks something like this:

1. Place the part on a brick;
2. Heat with a gas burner until glowing (heat as hot as the heater allows);
3. Place the heated workpiece completely in oil;
4. Remove and place on a paper towel to absorb excess oil;
5. Repeat the procedure 4-5 times until the metal is given the desired color.

Important! This method will not make the part pitch black; in addition, this coating is not resistant to mechanical damage and is more suitable not for decorative purposes, but specifically for preventing corrosion.

Blueing method

Steel blueing is a type of bluing in which the metal is given a darker color, not black, gray or brown, but a rich, beautiful blue. To prepare the solution you will need to prepare two solutions at once. No1 – add and mix 140 g of hyposulfite to 1 liter of water. No2 – dissolve 35 g of lead acetate (popularly “lead sugar”) in 1 liter of water. The solutions are mixed only before blackening begins, heated to boiling temperature, then the product is lowered into a boiling liquid and remains there until it acquires the desired color. At the end, you need to thoroughly rinse the part in cold running water, dry it, and then wipe it with a cloth moistened with machine or castor oil.

Blackening of metal must be carried out in strict accordance with the chosen technique and compliance with all necessary safety regulations.

Video: Several videos about do-it-yourself bluing at home

Step-by-step instructions on how and with what to produce metal bluing

How to blue steel at home. Burnishing steel black at home

Burnishing at home: features of the work:: SYL.ru

Steel bluing can be considered an industrial scale process. It involves applying a protective layer to the product or surface - iron oxide, which has certain characteristics. But bluing at home is also done quite often. It cannot be compared with the oxidation process in a factory, but this technology is successfully used in practice by home craftsmen. There are several methods of bluing, among them hot, cold methods and the method of exposure to oxidizing agents.

Cold way

Burnishing at home can be done using a method that does not involve hot processing. It is applicable if metal parts cannot be subjected to significant loads. Among the solutions that can be found in the home craftsman's arsenal, there are those that can form a special protective coating on the metal surface. One of these is the so-called Parisian oxide. It should be applied with a brush, and then wash the surface or product. This process cannot be called lengthy or costly.

If there is a need to achieve a longer-lasting effect, the treatment can be carried out by complete immersion in the solution. After this, the part or surface should be washed using any product and wiped with a rag, which should first be moistened with alcohol. If such bluing was done at home yourself, then you can check its effectiveness using ordinary water. Moisture is applied to the base with a brush, after which not a drop should form, but a uniform film.

Hot way

If the metal can be subjected to high temperatures, then it is first tarred and then burned with a blowtorch. For the process you need to prepare gun or olive oil. This technology is effective, harmless and low-cost. It is worth noting that the effect lasts much longer than when processed using the method described above. During the work, heating should be carried out slowly, everything starts at 200 degrees and ends at around 400 degrees. If you do this kind of bluing at home yourself, a brown and then a black layer will form on the surface. It is important to avoid using excessive amounts of oil, as otherwise stains may form on the surface.

If metal bluing is to be done at home, then the best method for hot processing is a composition that is prepared from 20 parts of grease and one part of sulfur. The resulting mixture should be applied to the surface in as thin a layer as possible, and then the master subjects the product to flameless firing. The formed film will become perfectly uniform.

Burnishing with oxidizing agents

This method involves the use of molten oxidizing agents, these can be nitrites or nitrates. The metal part should be dipped into molten salts, holding it there until the surface turns black. Instead of these substances, which are quite dangerous, you can use alkaline or hot saline solutions.

What else does a master need to know?

Blueing metal at home can be done quite simply, as evidenced by the recommendations described above. Oxidizer technology is a method that is widely used for blackening copper, cast iron and steel products. The former acquire a rich red color after completion of the process. But if you are faced with the task of blackening hardened and heat-sensitive products, then processing them using this method is not recommended.

We should not forget that after bluing the gun at home has been completed, it must be washed using special products, dried, and then lubricated with oil.

Features of bluing

In industrial conditions, bluing of the top layer of metal is carried out by changing the structural composition. Among other things, a protective coating is applied in a special way, which helps protect against corrosion. Using technologies that are used in industrial enterprises at home is not only economically unprofitable, but also impossible. You can fight rusty metal yourself by applying compounds, which are sold in a wide range in stores of the relevant goods. A sufficiently high-quality result can be achieved by using saltpeter. Among other things, you can effectively remove blackening using a special pencil. In some cases, steel bluing is done at home with citric or phosphoric acid.

Secrets of the work

Initially, you need to thoroughly grind and clean the surface. Then degreasing is carried out, for which a special solution should be prepared. The selected product is applied in the next step. After degreasing is completed, the product must not be touched, otherwise all work must be performed with rubber gloves.

Conclusion

Burnishing barrels at home, as a rule, involves the application of substances that are classified as hazardous. That is why the master must follow the rules and provide special conditions that guarantee safety and prevent injury. Due to the fact that the solution used for bluing contains chemically active components and acid, it is necessary to use only special containers. This will prevent damage to the materials in the products and will not cause you unnecessary trouble, which is very important for the successful completion of the work.

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Several ways to do bluing at home

Blueing, or oxidation, has been known for a very long time. Previously, this treatment was used to protect the metal from corrosion, but now it is mainly for decorative purposes. It will not be difficult for a craftsman to carry out bluing at home in order to give a metal product an interesting look or to restore a hunting rifle. To do this, you only need desire and certain knowledge.

Ways to make steel bluing at home

The simplest of them is coating the metal with oil and then heating it. This is done as follows. The workpiece is cleaned and degreased, after which it is rubbed with a thin layer of drying oil (or vegetable oil). Then it is placed in a heating cabinet or a conventional oven and heated to four hundred degrees. The result is a durable decorative film of a dark brown hue.

Another way to perform bluing at home is to boil metal blanks in a strong alkali solution (potassium, sodium hydroxide). In this case, the metal acquires a beautiful blue tint, but the bluing is not very pronounced - light. Therefore, this method is more suitable for small cylindrical metal objects. To obtain a more pronounced blue-black hue, the workpiece must be boiled in a solution consisting of 1 liter of water, a quarter kilogram of sodium nitrite, 700 grams of sodium hydroxide and 200 grams of sodium nitrate.

The most difficult way to do bluing at home, but also one that gives the best results, is to boil the workpiece in molten sodium nitrate. The process must take place at a temperature of 350 degrees Celsius. In this way you can obtain a very durable, beautiful bluish oxide film.

Burnishing gun barrels

All the methods described above for making bluing at home are of little use for restoring gun barrels. For such work there is a special composition that can be purchased in specialized stores. In case such a product is not available in accessible stores or for some reason its use is undesirable, below is a good way to blue the barrels at home.



A stainless steel pipe of suitable diameter and length is used as a container. One end of the pipe is welded.

1. The barrels are cleaned of rust and old bluing using abrasive materials, and then polished with a felt wheel.

2. The barrels are closed at both ends with chemical-resistant plugs. The surface of the workpiece is degreased in two stages. First, it is simply wiped with gasoline, and then the barrels are immersed for twenty minutes in a solution heated to 70 degrees. The composition of the solution is as follows: one liter of water, 50 g of sodium hydroxide, thirty grams of soda ash, the same amount of sodium phosphate and 5 grams of silicate glue.

3. To remove the old oxide film, pickling or light etching is used. The barrel is dipped in a five percent sulfuric acid solution and kept there for one minute.

4. The main process occurs using an aqueous solution of orthophosphoric acid (0.7/100), ammonium chloride (6/100), sodium hyposulfite (8/100) and nitric acid (0.3/100). The trunks are “cooked” at a temperature of 70 degrees. In one hour.

5. To fix the resulting oxide film, the workpiece is immersed for five minutes in a chromium solution (120 g per liter of water). The solution temperature is 70 degrees.

After the procedure, metal bluing at home is completed by thoroughly washing the barrels, and in no case should they be handled with bare hands. With each processing method, special attention should be paid to safety measures! All substances are very aggressive!

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Blueing metal at home. Treatment.

Blueing of steel is a process mainly on an industrial scale. It involves applying a protective layer of iron oxide, which has certain properties, to the metal coating. However, blueing of metal at home also occurs. It, of course, cannot be compared with the process of real oxidation, yet this method is quite successfully used in practice.

There are three ways to blue metal at home:

• cold;
• hot;
• exposure to oxidizing agents.

Let's look at each of them separately:

Cold processing:

If metal parts are not subjected to high mechanical loads during use, they can be blued using a cold method.

Among the solutions available in the home arsenal of craftsmen, there are those that leave dark deposits on metal surfaces. The use of these solutions during certain chemical reactions may cause the formation of black films. One of the most commonly used solutions is “Paris oxide”. When applying the substance with a brush, a black film forms on the metal surface, after which the product must be thoroughly washed. This process is completely inexpensive and does not take long.

If a much longer-lasting effect from the treatment is required, the bluing process must be carried out by complete immersion. After the procedure, the part is thoroughly washed with any detergent, then wiped with a cloth soaked in alcohol. You can check the bluing using ordinary water: water is applied to the surface with a brush, forming not droplets, but a uniform film.

Hot processing:

When using this method, the metal part is first oiled and then burned using a blowtorch. The oil used is linseed, olive or specially used for weapons. The method is harmless, low-cost and quite effective, and the effect lasts longer than with cold processing.

During processing, heating is carried out slowly, starting from 200 - 400 degrees. A brown layer first forms on the surface, and then the necessary black layer. It is important not to use too much oil, as too much can cause stains.

How to install laminate flooring yourself and correctly. - there is more useful information here.

The best hot working method is to use a mixture of 20 parts grease and 1 part sulfur. The resulting mixture is applied to a metal surface in a thin layer and subjected to flameless firing, after which the resulting film will be perfectly uniform.

Treatment with oxidizing agents:

When using this method, metal surfaces are exposed to molten oxidizing agents, mainly nitrates and nitrites.

You will be interested in this article - Roofing with corrugated sheets.

Metal parts are dipped into molten salts until a black color is formed. Instead of these rather dangerous substances, it is also possible to use hot salt and alkaline solutions.

The method is widely used for blackening cast iron, steel, and copper products. The latter, after bluing, acquire a rich red color. However, heat-sensitive and hardened products should not be processed using this method.

After treating metal surfaces using all the methods described above, they must be thoroughly washed with detergents, dried, and then do not forget to lubricate them with oil.

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Burnishing steel with a chemical liquid at home

Steel blueing is a complex procedure that is widely used. It allows you to paint a metal product, protect it from rust and other things. In addition, decorative finishing of materials is carried out in this way. Blueing of steel is carried out in different ways. The most common is the use of chemicals.




As a result, the iron oxidizes and a protective shell is formed on its surface. The latter protects products from damage and exposure to adverse factors. At the same time, the metal can retain its natural color. This can be achieved by oils and acids that are used in the bluing process. The degree of heating of chemical compounds also affects.

Burnishing steel at home

This procedure is mainly carried out in production. Since it is quite labor-intensive, it requires the use of special equipment and materials. But, as practice shows, it is quite possible to do it at home. The main thing is to choose the right oxidation method. There are some that can be done effectively at home. They are carried out quickly and simply using available tools.



In this way, the external appearance of the product can be improved and the metal will be more attractive. In addition, its protective properties are improved. It is resistant to corrosion, since after the procedure a thin protective film is formed on the surface of the product. If work is carried out at home, then citric or phosphoric acid, varnish or oil are usually used. A special solution is prepared from these components and applied to the metal product.




If we talk about industrial technologies, they involve the use of other means. This ensures high quality processing. But, as practice shows, the procedure carried out in domestic conditions is not inferior in this indicator. She is also able to demonstrate excellent results.

Execution Rules

Burnishing steel at home involves chemical surface treatment. Thus, its top layer is removed and a protective layer is applied. Since it involves the use of chemicals, it is quite dangerous. Therefore, when carrying out it, it is necessary to follow some rules. They will protect your hands and other parts of the body from burns that can be caused by substances.

The first thing you should pay attention to is the container in which the mixture is prepared. When choosing it, it is better to give preference to dishes made of porcelain, glass or earthenware. Metal containers are prohibited.




The second rule concerns the mechanical stage of the work. When carrying out this procedure, it is necessary to wear safety glasses and a special uniform. They will protect your skin and eyes from exposure to aggressive chemicals and acids. In this case, you should carefully approach the choice of premises. It should have good ventilation and powerful exhaust.

Surface preparation

Chemical bluing of steel involves performing various interrelated works. First you need to prepare the surface. This stage consists of its high-quality and uniform cleaning. This will remove a layer of dirt, dust and grease. Powdered pumice, sandpaper, and fine-grained sand will help you cope with this task well.




After this, it is necessary to prepare the reagents that will be used for bluing. It is worth considering their properties. Since not any liquid can be used for bluing steel. Some can ruin products. To prevent this, you need to use them correctly.

Chemical oxidation

The most common means for bluing steel is liquid. This method of carrying out the procedure is distinguished by its effectiveness. It allows you to get good results, but subject to compliance with the rules. This method is based on the ability of steel to oxidize.



The process consists of the following work. First, the surface is cleaned and degreased. After this, a special solution is prepared that will be used. It is important to follow the proportions and rules of its preparation. Even the smallest flaws can lead to a deterioration in its properties. As a result, the end result will be of poor quality.

To prepare the solution you will need plain water, sodium nitrate and technical soda. All components are taken in quantities of 100 grams. The solution must be prepared in a porcelain container. All ingredients are thoroughly mixed. After this, the mixture is heated to 130 degrees.



To carry out bluing, the product must be placed in a hot solution. Leave it for a while. 30 minutes will be enough. After which the product must be removed and washed with water. Distilled is good for this job.

The final stage of work is drying the part and lubricating it with oil, which is used for machines. This work can be done with a soft brush. In this case, it is necessary to cover the surface carefully and evenly. The result will be a homogeneous layer, as shown in the photo below. It will have a black color.

Determining the quality of work is easy. Just look at the surface of the metal. If all the rules are followed, it will be smooth. Thus, there is no need to sand the product.

Carrying out bluing is not an easy task. It must be carried out carefully and carefully. Safety rules must be followed. Otherwise, you risk harming your health.

You can watch the bluing procedure in the video below. The subtleties and features of the process are clearly shown here. They will help a beginner get good results when working at home.

To get a good result, you need to choose the optimal method of carrying out the procedure and use high-quality products. This way you can extend the service life of the part. It will be reliably protected from various adverse factors that are inevitable when using metals.

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in saltpeter, clover, rusty varnish, pencil

There is a misconception that it is impossible to blue metals at home, and this technical operation, in any case, should only be performed in factories.

Currently, there are several different ways in which you can effectively deal with rusty metal at home.

This type of processing is necessary in order not only to make the metal more attractive.

With its help, the protective properties against corrosion are significantly increased.

Do-it-yourself steel bluing at home is distinguished by simpler methods of metal processing, which use improvised means.



At its core, this method of dealing with rusty metal involves applying a variety of coatings to the surface being treated, which form a thin protective film on it.

At home, this can be done using citric or phosphoric acid, as well as using varnish or oil from which a certain solution is prepared.

Of course, industrial technology allows for better processing, but some methods of dealing with rusty metal at home show quite good results.

Features of metal bluing

In industrial conditions, the blackening of the top layer of metal is removed by changing its structural composition.

In addition, a protective coating is applied in a special way, providing high-quality protection against corrosion.

Using industrial methods to combat rusty metal at home is not only impossible, but also economically unprofitable.

Independent hot or cold coating is performed by applying some special compounds to the metal surface, which not only remove its blackening, but also form a thin protective film.

The means for bluing can be purchased at any specialized store, and in a fairly wide assortment.

Thus, bluing in saltpeter allows you to achieve a fairly high-quality result; in addition, a special pencil for bluing allows you to effectively remove the blackening from the metal.

In some cases, you can use orthophosphoric or citric acid, and also prepare a solution for treating stainless steel in oil.

Regardless of which technology - phosphoric acid, citric acid or oil - is chosen to combat rusty metal, the entire process can be divided into several separate stages.

First of all, the metal surface is thoroughly polished and cleaned. After this, degreasing is carried out, for which a special solution is used.

It should be noted that depending on the part, its technical characteristics, as well as the chosen method for bluing, certain nuances and subtleties may arise, but the general algorithm of actions always remains unchanged.

It should also be remembered that after degreasing the surface to be treated, it should not be touched, which means that all work is best done with rubber gloves.

Basic processing rules

Blueing is essentially a chemical treatment of metal surfaces, in which not only the blackening is removed, but also a protective layer is applied.

These works are classified as hazardous, and therefore must be performed in compliance with certain rules and under special conditions.

Since the solution used for bluing contains chemically active substances with acid, special containers must be used for it.

In addition, such processing of metal surfaces also involves mechanical work, which means it is necessary to have on hand appropriate means to protect the eyes and skin.

You should also perform metal processing in a room that is equipped with a ventilation system or has a powerful exhaust hood.

In the video posted above, you can see how such processing of metal surfaces should be carried out.

When working with acid and other chemical reagents, you should use only those containers that are made of earthenware, porcelain or glass.

Immediately before starting bluing, you should carry out a uniform and high-quality cleaning of the surface, and also completely remove traces of dirt and grease from it.

In this case, sandpaper, powdered pumice, and fine-grained sand can be used as processing material.

It should be remembered that the liquid contains a variety of chemical elements that, if used incorrectly, can harm the product.

You must also ensure that the solution used does not come into contact with the skin or eyes, as this can cause serious injury or burns.

Chemical oxidation treatment

Most often, metal surface treatment is carried out using chemical oxidation.

This method is quite effective and, if the technology is followed, allows you to achieve a high quality final result.

This method of bluing metal is based on the ability of the metal to oxidize.

At the preliminary stage, it is necessary to mechanically treat the surface of the workpiece, as well as completely degrease it.

After this, the appropriate solution should be properly prepared.

For these purposes, you should take a container of a certain size, which must be made of porcelain.

After this, the solution should be thoroughly mixed and ensure that all components are dissolved in it.

The resulting mixture should be heated to a temperature of about one hundred and forty degrees Celsius, and the workpiece should be immersed in it for about thirty minutes.

After the specified time has elapsed, the part is removed from the solution and thoroughly washed with distilled water.

The metal surface treated in this way will acquire a pronounced black tint with a blue tint.

If the bluing was done correctly and in accordance with the technology, the metal will become smooth and does not require subsequent polishing.

In the video posted in the section, you can see how a metal surface is treated at home using a chemical solution.

Using rusty varnish

Many people use a method for bluing metal that is called “blueing with rusty metal.” With it you can achieve a flat and smooth surface at minimal financial cost.

Its essence lies in placing the workpiece in a corrosive chemical environment.

As a result of this bluing, red and black iron oxides appear on the metal surface.

To remove the red deposits, use a brush with stiff metal bristles, leaving the black oxide behind. It should be noted that this processing method is quite lengthy, but effective.

In any case, first the metal is mechanically processed and degreased, and only after that the product is placed in a special solution.

The liquid for bluing with rusty varnish is prepared in special porcelain containers, and it is necessary to use products to protect the skin.

The solution in this case is prepared on the basis of hydrochloric acid.

It must be poured in a small amount into the prepared container and mixed with iron rust, metal filings and nitric acid.

After this, water and ordinary vodka must be added to the mixture in equal quantities.

The solution must sit for a certain time, after which it must be drained to remove scale and precipitated salts.

Other bluing methods

Very often, a special pencil for bluing is used for metal processing.

Before using a pencil for bluing, the metal surface is treated mechanically and then thoroughly degreased.

Such bluing of steel, if all technological requirements are met, is quite effective and allows you to obtain a smooth and even surface. It is also very common to get rid of corrosion with varnish.

As in all other cases, before treating the surface with varnish, it is treated by mechanical action.

When working with varnish or pencil, it is necessary to use special protective equipment so that the product used does not come into contact with the skin.

You can also perform the treatment by painting the metal surface with a solution called “Clover”.

This method of painting with Clover is quite effective with minor corrosion of the metal surface.

In this case, it is necessary to paint the treated surface with Clover as thoroughly as possible, several times.

The composition Clover is sold in special small tubes. The price of Clover also varies from place to place.



Clover has a gel consistency. The main advantage of using Clover is its ease of use.

Simply sand the part, then degrease it with gasoline, and then apply Clover. After a few minutes, when the gel is absorbed, rinse off the residue with water.

It is best to burnish heavily damaged metal with a solution of saltpeter.

To prepare a solution of nitrate, only stainless steel utensils should be used, and the skin must be protected from contact with the mixture.

As a result of bluing with saltpeter, the metal surface acquires a pleasant reddish tint, which is complemented by a slightly bluish tint.

A solution of nitrate for bluing is prepared from one liter of water and a small amount of sodium nitrate, as well as caustic soda.

This mixture has a rather pungent, pungent odor, and therefore it is better to use a respirator when working with it.

Aluminum Surface Treatment

The method of bluing aluminum is called anodizing and allows you to give the product an aesthetic appearance and completely remove traces of corrosion.

Currently, many different parts are made from aluminum, including those that are susceptible to corrosion and require cleaning by bluing.

As a rule, various acids are not suitable for processing aluminum, since in this case the part may be deformed and damaged.

In some cases, active acids can be used for aluminum, but only in small quantities, generously diluted with water.

The surface of aluminum can be burnished with varnish, but only in a certain way.

A solution prepared from a small amount of sulfuric acid, abundantly diluted in water, is quite effective in bluing aluminum.

The product must be placed in a special container, and then a lead plate connected to a twelve-volt battery must be placed in it.

After bubbles form in the solution, an aluminum part is placed in it for a certain time. After this, the aluminum part is removed from the solution and dipped into blue pigment paint.

This method of bluing aluminum is considered popular, but it is highly effective and allows the metal to be well protected from corrosion during further use.

The processing of any metal by bluing must be carried out in strict accordance with the chosen technology and in compliance with safety regulations.

The final result largely depends on the method of preparing the solution and the quality of the components used.

Some methods of bluing metal at home can be seen in the video posted above.

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Blueing

Steel bluing is a chemical process used to obtain a thin protective film of iron oxides Fe3O4 on the surface of a steel part. It got its name because of the characteristic color of the part after processing (blue-black, raven’s wing); it also has the names “blackening” or “blueing” in the general case, regardless of the color - “oxidation”. The resulting film passivates the surface and protects the part from atmospheric corrosion and exposure to other aggressive environments.

Before bluing the steel, the part is first prepared, cleaned of rust mechanically, polished, degreased and pickled in an acid solution. You can degrease with solvent or alcohol. Etching is needed to remove all excess oxides from the surface, leaving bare metal.

The easiest way is to bluish the steel with oil. There are different methods, but the idea is simple: a thin layer of oil is applied to the part, after which it must be heated to 300-350°C. When oil burns, it leaves an oxide film on the surface. The first time there is no uniform coverage, so the process is repeated until the desired result is achieved. It is important to achieve uniform heating, otherwise the film will become stained, and not to overheat the part, as it may deform or loosen. Many people make the mistake of dipping a heated part into oil; this is wrong. It is necessary exactly the opposite: first smear, then heat. Any oil can be used, from sunflower to transmission or machine oil. This type of steel bluing has low coating strength. It is suitable only for decorative and protective purposes.

Burnishing steel using iron sulfate, iron chloride and nitric acid

To do this, you need to dissolve 15 g of iron, 30 g of vitriol and 10 g of acid per liter of water. A rusty coating will form on the product dipped into the solution; it must be periodically removed with a brush and continued dipping until the required color of the oxide film is obtained. Nowadays, in almost every city there is a store selling chemical reagents, so it is relatively easy to get them.

Blueing of steel using chromium (potassium dichromate). To do this, dilute 200 grams of chromium per liter of water and immerse the part in the solution for 20-30 minutes. After removal from the solution, it must be dried at high temperature (in the oven or over coals). Repeat the process until a uniform blue-black color is obtained. Then wipe the part with an oiled rag. Chrompik is a very common reagent; it is used in the leather industry.

To blue gun barrels, mix 1 part by weight of antimony trichloride with 3 parts of olive oil while heating. Then the mixture is applied to the part and left for a day. The process is repeated 10-12 times, after which the barrel is washed, dried and polished. The color is greenish-brown.

As can be seen from the above, bluing steel at home is a completely feasible and uncomplicated process. It can be used for any steel products in cases where other methods of corrosion protection, for example, painting, are not applicable.

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what is it, basic rules of oxidation and processing

Many people mistakenly think that it is impossible to blue metals at home; this is only done in factories. However, today there are various ways in which oxidation can be carried out quite effectively at home. This type of processing is necessary not only to make the metal quite attractive, but also to significantly increase its protective properties against corrosion. Burnishing metal at home is distinguished by fairly simple processing methods, in which improvised means are used.

This method of dealing with rusty metal involves applying a variety of coatings to the surface being treated, resulting in the formation of a thin protective film. At home, this is done using phosphoric or citric acid, as well as varnish or oil from which the solution is prepared. Industrial technology provides for higher quality processing, however, in domestic conditions, some methods can show quite good results.

What is metal bluing

Steel tends to rust; corrosion can occur even at the slightest contact with water, if the surface is not wiped with an oily rag after that. Even high air humidity can cover metal with rust. To protect it, it is coated with a special anti-corrosion paint, but this method is not suitable for threaded connections and moving parts. Therefore, to protect against corrosion, bluing is used, which many call blackening or oxidation.

Do-it-yourself bluing is done by applying a special composition to the surface of the metal, which forms a thin protective film on its surface. You can purchase the composition at any specialized store; the selection is quite wide. The best quality result is shown by bluing in saltpeter.

Regardless of what technology will be used to combat rusty metal, the entire process is divided into several stages:

• first, grind and clean the metal surface;
• then it is degreased using a special solution;
• then very carefully apply the purchased oxidation agent;
• Finally, surface finishing is performed.

Do not forget that certain subtleties and nuances may arise depending on the chosen method of bluing and the technical characteristics of the part. However, the general processing rules always remain the same. It is also necessary to remember that after the surface has been degreased, it should never be touched, so work is usually done with rubber gloves.

Basic processing rules

At its core, bluing is a chemical treatment of a metal surface, which allows not only to remove the blackening, but also to apply a protective layer. Such work is considered dangerous, so it must be performed in compliance with certain rules. Since the solution used for oxidation contains chemically active substances with acid, it is necessary to use a special container for it, which must be:

• porcelain;
• glass;
• earthenware.

Metal containers are strictly prohibited.

In addition, the processing of metal surfaces involves mechanical work, so you should always use eye and skin protection. Burnishing should be carried out in a room with a ventilation system or powerful exhaust hood.

Before you start bluing, the surface should be thoroughly and evenly cleaned, completely removing traces of grease and dirt. For this you can use:

• powdered pumice;
• sandpaper;
• fine-grained sand.

Before starting work, it is recommended to familiarize yourself with the properties of the reagents used. Fluid for bluing may contain a variety of chemical elements that can harm the product if used incorrectly.

In addition, you must ensure that the solution does not get into your eyes or skin, which could result in a burn or serious injury.

Chemical oxidation treatment

Chemical oxidation of the metal is quite often carried out. This method is quite effective, and if you follow the technology, you can ultimately achieve good results. Oxidation is based on the ability of a metal to oxidize.

The preliminary stage consists of mechanically treating the surface of the workpiece and degreasing it. Then they begin to prepare the solution. It is very important to do this correctly. To do this, take a porcelain container of certain sizes. 100 ml of ordinary water is poured into it and a little sodium nitrate and 100 g of technical soda are added. The solution is thoroughly mixed so that all components dissolve in it. The resulting mixture is heated to a temperature of 140 degrees and the workpiece is immersed in it for half an hour.

After this, the part is removed from the solution, thoroughly washed with distilled water, dried and generously lubricated with machine oil using a soft brush so that the layer is uniform. A metal surface treated in this way becomes black with a blue tint. If oxidation was carried out correctly, in compliance with all the rules, then the metal as a result becomes smooth and does not need to be polished again after that.

Application of rust varnish

There is a method of blueing a metal surface called “rusty metal”. With its help, the surface becomes even and smooth at little financial cost. Its essence is as follows: the product being processed is placed in a corrosive chemical environment. As a result, black and red iron oxide forms on the metal surface.

To remove the red coating, use a brush with stiff metal bristles; the black oxide remains. This method of processing is quite time-consuming, but very effective. First, the metal is mechanically processed, degreased and placed in a special solution.

The liquid that will be used for bluing using the rusty varnish method is prepared in porcelain containers. The solution is prepared on the basis of hydrochloric acid. It is poured in a small amount into a prepared container and mixed with metal filings, rust and nitric acid. Then the solution is thoroughly mixed so that the chemical reaction accompanied by the release of gas completely stops.

After this, water and vodka are added to the mixture in equal quantities. The solution must sit for some time, then it is drained to remove scale and precipitated salts. Then the metal being processed is placed in the mixture for some time and waited until it turns black, and then thoroughly washed under water.

Other bluing methods

Quite often, a special pencil is used to oxidize metal. Before you start working with this chemical pencil, the metal surface should be treated mechanically and then degreased. There should be no traces of grease or dirt left on the metal surface. In this case, it is imperative to use special protective equipment.

In addition, oxidation is often performed by painting the metal surface with a solution called “clover”. This method is quite effective if the metal surface has minor corrosion. In this case, coloring is performed to the maximum, several times.

If the metal is very damaged, then it is best to burnish it with a solution of saltpeter. To prepare it, you must use stainless steel utensils. Take 1 liter of water and a small amount of sodium nitrate and caustic soda. The resulting mixture has a rather pungent odor, so it is necessary to use a respirator for work. As a result of this bluing, the metal surface acquires a reddish tint with a bluish tint.

Conclusion

Metal processing using bluing must be carried out in compliance with all necessary conditions and safety regulations. The effectiveness of the result depends entirely on which method was used and the quality of the components used. Oxidation helps protect the metal from corrosion for a long time.

Many people still believe that bluing metal at home is impossible to do. We hasten to gladden you that this is not the case. In this article we will not only talk about bluing technology, but also tell you about different ways to ensure that the workpiece is gray, blue or black.

Why is this necessary?

By bluing, two problems are solved at once:

1. After processing, the metal has a more attractive appearance.
2. The problem with metal corrosion is solved - the blued part does not rust.

Bluening process

During the bluing process, a film of iron oxide forms on the part. Its thickness depends on the technology used and can range from 1 to 10 micrometers.

There are several ways to process metal:

• Alkaline.
• Acid.
• Thermal.

Alkaline method

In alkaline solutions, bluing is performed with oxidizing agents at a temperature of 130 – 150°C. The basis of alkaline oxidation is the process of iron oxidation.

When boiling, an alkaline solution gives off a very unpleasant odor, so it is better not to work with it in an apartment (or any other enclosed space).

• It is best to use a stainless steel container to prepare the solution.
• Pour 100 ml into this container. water and dissolve 120 g in it. caustic soda and 30 gr. sodium nitrate. Stirring is carried out until the solid sediment disappears.
• The resulting mixture must be heated to 130‒150°C.
• The part is immersed in a boiling solution, but it should not touch the walls of the container.
• After 20 minutes the metal will turn black, after which our part must be removed and washed with distilled water.
• After the part has dried, it must be lubricated with machine oil and then wiped dry.
• The surface is smooth, wear-resistant and does not require additional polishing.

When bluing large parts using this method, finding a stainless container of a suitable size may become a problem.

Acid method

Acid bluing is performed in acidic solutions using chemical or electrochemical methods.

• If the part is rusty, then you need to clean it with sandpaper. You can speed up the cleaning process by using an angle grinder with a wire brush.
• Now you need a cleaning solution. This can be ethyl alcohol with kerosene or kerosene. You can also use sodium triphosphate.
• The part is immersed in the solution for 15 minutes, after which it is washed with running water and dried (or wiped).

While the part is drying, prepare a solution for acid bluing. The following components will be required:

• water – 1 l.
• tannic acid – 2 gr.
• tartaric acid – 2 gr.

Now let's start bluing the metal part.

• The components are mixed and heated to 150°C.
• The part is lowered into the container and left for 15 minutes, after which it must be rinsed with running water.
• You can finally get rid of the solution on the part by dipping it in boiling water.
• The final stage of bluing will be immersing the part in machine oil for 1 hour, after which it must be wiped and can be used for its intended purpose.

The acid bluing method can also be done using the cold method. To do this you will need Iron(III) Chloride or "Rusty Varnish".

Thermal method

Thermal bluing technology is the oldest, and probably the simplest. The essence of the method is to heat a metal product in the open air until the oxygen contained in the air enters into a chemical reaction with the top layer of the part. The stronger the heating, the darker the part becomes, because the oxidation process takes place at a greater depth.

Using oil

The method in question is simple to use at home. We will need the following ingredients:

• Machine oil – 500 ml.
• Metal container for oil.
• A tool for holding the part (pliers, pliers, pliers, etc.).
• Gas-burner. If it is not there, then you can use a gas stove or a hair dryer.
• Paper napkins or rags.

1. The parts must be laid on a non-flammable surface (brick, for example).
2. The hairdryer should be set to high heat.
3. The part needs to be heated as much as possible.
4. The heated metal, held with pliers, must be lowered into the bath so that it is completely immersed in the oil.
5. After removing the part from the oil, place it on a paper towel to absorb the oil.
6. The part needs to be heated again and lowered into the oil - the process is repeated 3-4 times.

Each bluing cycle makes the part darker.

The bluing process described will not turn the part black. In addition, the coating is not durable and is easily damaged. The technology is more suitable for rust protection than for decorative purposes.

How to make steel blue

The technology for blueing metal is more complex and requires not only more effort, but also the presence of some equipment. We'll need a forge. It is very good if it has automatic blowing. It is clear that not everyone has a forge, so if you don’t have one, you can use an ordinary metal barrel, half filling it with chopped brushwood.

So, we have a part, now we need a metal box to fit its size.

• It needs to be filled with fine birch charcoal and placed in a thoroughly heated forge (or in a barrel).
• The part to be treated must be wiped with vinegar and left to dry.
• You should wait until the coal in the container begins to smolder.
• The workpiece is placed in the smoldering coals and left there until a slight blue color appears.
• As soon as the part begins to turn blue, it needs to be pulled out and cleaned with soft charcoal.
• The part is again placed in its place in the drawer and, after changing the color of blue, it is again pulled out and cleaned.
• The work is repeated until the part acquires the desired color.

It is important to monitor the heating process and remove the part in time, otherwise its color will change to gray.

Blue without heat treatment

You can achieve the desired shade of blue without heat treatment - using a special solution.

To complete the work you need 2 reagents and water:

1. Potassium hexacyanoferrate (red blood salt) - 2.5 g.
2. Iron sesquichloride - 2.5 g.
3. Water – 1 l.

Take 2 0.5 liter jars and dissolve each ingredient in them separately. There will be no problems with this, since water is an ideal solvent for them. After this, the solutions are mixed, and a steel part is placed into the resulting mixture. It is necessary to carefully monitor the oxidation process. When the desired shade of blue is achieved, the part is removed from the solution and dried.

2 more ways

1. In order to make a part dark blue, you can melt the sulfur by mixing a small amount of soot into it. The part is placed in this composition, and the process of color change is controlled.
2. By heating the saltpeter to more than 320°C, we will bring it to a liquid state. Further, as in the previous method.

There are many more ways to blue metal, thanks to which you can achieve a beautiful and durable color of the part, but not all of them are suitable for use at home. We tried to describe the simplest and, if possible, safe ones.

Any of the methods described above for bluing metal can cause harm to human health! You need to take safety precautions in advance, remembering that hot metal can cause thermal burns, and reagents can cause chemical burns. In addition, reagents can cause fumes poisoning. Many reagents are flammable and should not be heated, so be extremely careful and follow the instructions carefully.

The simplest ways

Most housewives have vinegar, tea and citric acid at home. And Coca-Cola lovers can not only wash off tar from their cars with it, but also use it to blue metal.

We will not describe each method, since they are almost the same and are most often used for blackening knives and other kitchen utensils. Let us describe the method of bluing a knife.

So, we will need any of these ingredients:

1. Table vinegar.
2. Citric acid – 1 sachet.
3. Coca-Cola (you need to release the gas in advance).
4. Black tea (infusion).

Now about the technology of metal blackening.

• The knife needs to be degreased and poured boiling water over it to keep it hot.
• Any of the listed liquids is filled into a plastic bottle with the neck cut off so that only the handle remains outside.
• The knife must be shaken frequently to ensure that there are no air bubbles on the blade.
• Periodically, the knife should be removed from the liquid and the blade should be wiped, removing oxides in this way.
• When the metal becomes the desired color, the bluing process stops.

The coating is not very durable. If desired, it can be removed and reapplied.

In your comments, you can talk about your method of bluing at home, sharing your opinion and impressions of the work performed.

Video

This video shows how knives are etched in different substances:

See how metal blackening is done using bluing fluid:

Blueing of metal at home is carried out in different ways, which do not require special skills or experience. It is enough just to know the technology for performing this process.

Blueing is also called oxidation. This is a long-known metal processing method that was originally used to protect against corrosion. Now it acts more as a decorative coating - products take on an attractive appearance.

Features of the metal bluing process

By performing bluing at home, you can save a lot of money on paying for the same services at a metalworking company. All you need to do is apply a special composition to the surface. It will blacken and form a protective film.

Before bluing, the metal is processed - it must be cleaned and degreased. When everything is ready, all that remains is to choose the appropriate method and proceed according to the scheme.

To avoid burns and other injuries, you should follow the following safety rules:

• Wear gloves.
• Protect chemicals from accidental spillage and store in original sealed containers.
• Burn medications should be available near the work site to provide assistance if necessary.
• Ventilate the room well.
• Use non-metallic containers.

To work, you will need sandpaper to clean the surface. Then the metal is degreased with a substance inert to it. This can be done with any organic solvent - acetone, B-70 gasoline, perchlorethylene. Its surface is inert (impervious) to these substances.

Metal processing methods

They involve the use of various chemicals, which, when interacting with metal under certain conditions, produce a durable film. The treatment option is selected depending on the desired end result - some add a decorative appearance, others provide good protection against corrosion. The color of the product is also different.

Alkali bluing

The most commonly used method of bluing metal is chemical oxidation with an alkaline reagent. The result is a fairly high-quality and durable coating if you strictly follow the technology. The method is based on the oxidizing properties of the metal. The process takes place at high temperatures - 135-150 degrees, and a specific odor is released.

It is more advisable to carry out bluing using the alkaline method in a non-residential, well-ventilated room or on the street.

The first step is degreasing and thoroughly cleaning the surface of the metal product. Oxidation at home will not be of high quality without preparing the correct alkaline composition. It is prepared as follows:

1. 100 ml of clean water is poured into a porcelain container.
2. Add 100 gr. technical soda and 30 gr. sodium nitrate.
3. The solution is thoroughly mixed and heated to 135-150°C.

The metal is placed in the finished composition for 30 minutes. Then the product must be taken out, rinsed with distilled water, dried and evenly lubricated with machine oil.

As a result, the metal part acquires a bright black color with a blue tint. To obtain a thicker oxide film, the amount of alkali used is increased.

Acid oxidation

Before bluing a metal part, its surface is cleaned with sandpaper, and it can be degreased by placing it in sodium triphosphate or kerosene for 10-20 minutes. While the part is drying, you can prepare a solution:

1. Tartaric and tannic acids in an amount of 2 grams are diluted in 1 liter of water.
2. The solution is thoroughly mixed.
3. Heats up to 140-150°C.

The metal is lowered into the heated mixture for 15 minutes. Afterwards, it should be rinsed with plain water or boiling water - if you need to better rinse off the solution. The final stage is to immerse the metal in machine oil for 1 hour. The part can then be taken out, wiped and dried - now it is ready for use.

Thermal method

This option of metal bluing appeared earlier than the others. In terms of execution technology, it is the simplest, but the result is high-quality. It is based on the property of a metal to oxidize when heated and interacting with oxygen. The intensity of oxidation can be adjusted by heating force.

For thermal exposure you will need:

• 500 ml machine oil;
• capacity;
• construction hair dryer or gas burner;
• pliers;
• paper napkins.

The treatment is carried out on a brick surface. You can choose another place, the main thing is that it is non-flammable.

Algorithm of actions:

1. Keep the metal part under a hairdryer turned on at maximum power.
2. When it warms up, put it in oil. This can be done with pliers so that the metal is completely submerged.
3. Take out and blot the product with a napkin.
4. Repeat this procedure 3 more times in a row.

This simple bluing is used to form a protective film on the metal surface - it protects well from corrosion. It will not be possible to add black color and decorativeness using this method.

Metal bluing in the brown spectrum

If a brown oxide film is enough to decorate the metal surface, then this method will be the best solution. It is based on the properties of the main ingredient - iron sesquichloride, or iron (III) chloride FeCl3. This substance will be required in an amount of 100 grams. The second necessary product is olive oil (1 kg).

After mixing the ingredients, a paste is obtained. The metal is covered with an even layer. After 3-5 hours, you need to sand the surface with a metal brush. The process should be repeated several times.

The resulting composition is coated on a steel product and left to react for a day. Afterwards, wipe the surface with a woolen cloth and reapply the product for 1 day. When time has passed, all that remains is to wipe the product again with wool and polish it with a waxed brush.

You can make this method even simpler - use only iron sesquichloride in the process, which is diluted in water at the rate of 150 grams per 1 liter. The metal is immersed in such a solution for the required time to obtain an anti-corrosion film of the desired brown shade.

Video: Blueing metal in oil

Keeping hunting weapons in order is the responsibility and concern of every owner. Maintenance requires some effort, but for true lovers it is not a waste of time. The ability to extend the service life and eliminate the appearance of traces of corrosion, shells or other defects on gun barrels is of great importance for successful hunting and the owner’s own safety. The traditional way to protect weapon metal from rust is bluing, which has to be done from time to time. Coating application is a technically simple procedure, but requires considerable experience and skills. Many owners blue their weapons at home, which saves time and provides the highest possible quality of protection. Sometimes this option is the only available method of coating, so it is useful for every owner of a hunting rifle to have an idea about it. Let's consider what this procedure is and how accessible it is for independent implementation.

What is bluing?

Burnishing is the application of a thin film of oxides to the previously prepared surface of steel or cast iron parts, protecting against corrosion and giving the metal a bluish-black color. The thickness of the film ranges from 1 to 10 microns; the thicker it is, the deeper and darker the color of the coating. The classic method of bluing, used for several hundred years, is to apply drying oil or linseed oil to the surface of heated metal. The result is a fine-crystalline coating that has protective anti-corrosion properties and a pleasant blue-black color. It is customary to judge the heating temperature by color, although this method is not very accurate. The blue color, most suitable for bluing, appears when steel is heated to 300-320°.

The coating obtained in the traditional way was not distinguished by proper strength, durability, and did not provide complete protection against rust. Over time, other, more effective methods of bluing metal were developed. Most of them were created specifically for weapons, since the specific service of weapon metal did not allow other finishing methods. One of the reasons for the need to use other coating methods was the task of abandoning the heating of weapon barrels, which had a negative impact on the condition of the metal, its physical and chemical properties.

What is it used for?

Initially, the procedure was carried out solely for the purpose of protection against rust, since there were no other types of coating, and the operating conditions of the weapon greatly contributed to the development of corrosion processes. Currently, in addition to its protective functions, bluing is considered as a decorative coating that gives weapons a traditional look. It is noteworthy that the appearance of a weapon is considered by a large number of owners to be one of the most important components of its performance, while protection against corrosion is not considered a problem at all. However, all currently used types and methods of bluing provide a sufficient degree of protection of the metal surface from moisture. It is also necessary to understand that any bluing agent does not create a coating layer, but only promotes the formation of a reaction as a result of which this layer appears on the surface of the metal.

Types of bluing

There are the following types of metal bluing:

• alkaline. The steel surface heated to 135-150° is covered with a thin layer of alkaline solutions, causing an oxidation reaction and the creation of a protective film;
• acidic. Produced by electrochemical or chemical methods using acid solutions;
• thermal. Refers to traditional methods of bluing, although there are more modern technologies with the formation of protective films in vapors of ammonia-alcohol compounds or in molten salts.

There are a huge variety of methods for applying protection, from complex multi-step processes to simpler and faster procedures. All of them are characterized by a limited period of validity and do not provide absolute protection from moisture. The barrels of hunting rifles must be blued from time to time, and the condition of the weapon must be constantly monitored. Coating cannot be considered as a final solution to the problem; it is only a way to somewhat reduce the consequences of contact with water and slow down the rate of rust formation.

What methods are available to perform at home?

Complex technological operations are not possible at home, but simpler procedures are quite possible. There are several basic bluing methods:

• cold;
• hot;
• oxidation.

All three methods can be done at home, for which you need to acquire all the necessary materials and equipment, as well as study and understand in detail the physical and chemical essence of the processes. It is not recommended to get down to business without understanding the meaning of the operations being performed. Any method consists of the same steps:

1. Cleaning, removal of old coating and rust.
2. Grinding, removal of cavities, small scratches, dents.
3. Degreasing. The surface layer of fat is removed, for which various chemical reagents are used. After completing this stage, work with metal only with rubber gloves.
4. Actually bluing.
5. Finishing the metal surface.

The most important point (apart from the coating itself) is degreasing. After this you can start bluing. Let's consider the possible options.

Cold bluing

The principle of cold bluing is simple - a special liquid is applied to a previously prepared surface. There are ready-made formulations:

• raven 3;
• Parisian oxide;
• rusty varnish.

The first two products are sold in stores. With the third, the matter is more complicated - in its finished form it is stored for a long time, but it is practically never on sale, there are only advertisements for the sale of old stocks. Making rusty varnish is a complex and dangerous procedure, since you have to mix 50 ml of hydrochloric and 54 ml of nitric acids, 30 g of steel or cast iron filings, and 20-30 g of scale.

All this is dissolved in 1 liter of distilled water, not immediately, but gradually:

1. A third of nitric acid and a third of chips with scale are carefully poured into hydrochloric acid. The reaction will begin, you must wait for it to subside.
2. Repeat the procedure and wait for the end of the reaction again.
3. Pour out the remaining chips and scale, pour out the last third of the nitric acid. Seal and leave for a day. Then add a liter of distilled water to the resulting brown solution, after which the rusty varnish is ready. You can use it for a long time, it becomes harmless and does not require special precautions.

The composition is applied using a regular brush.. It is necessary to ensure the uniformity and penetration of liquids into all corners and crevices of the parts. After finishing the work, the part is washed and polished.

Hot bluing

This method is the easiest. First, the part is heated, after which it is immersed in oil (as an option, the surface is smeared with a swab dipped in oil). The best option (as it is believed) is linseed or hemp oil, somewhat worse - drying oil. Mineral (machine) oil can also be used, but after it the results are considered the worst. Some masters advise waiting a while after applying the oil, then removing the excess. Others recommend baking the butter with a blow torch, which creates a thick black coating.

There is definitely no best recipe, since everyone has their own conditions for heating and applying oil, different temperatures and other nuances that affect the result. Everyone agrees on one thing: after the first application of oil and a short exposure, it should be thoroughly wiped off. This allows you to remove residual fats, which in any case cannot be dissolved during degreasing. The procedure of heating and applying oil is then repeated several times until the best result is achieved. In this case, you must act carefully, since the properties of the metal change when heated, and you can loosen the barrels too much.

Oxidation

Various types of nitrates or nitrites are used for oxidation. The procedure consists of immersing the prepared part in the molten mixture. The temperature is quite high, which is a serious limiting factor for use, since strong heating is contraindicated for critical parts, and gun barrels are such. There are many recipes for oxidizing agents designed for different temperatures, but to obtain the maximum effect, you must have strictly dosed heating that promotes an optimal reaction regime. It is difficult to organize this at home, so self-blueing by oxidation in artisanal conditions is rarely used.

Safety regulations

Carrying out the bluing procedure at home creates a certain danger both for the master himself and for others. It is necessary to understand that the term “home conditions” itself is quite vague and can be interpreted within wide limits. Any coating method requires heating or the use of aggressive or active chemical compounds. Therefore, it is unlikely that it will be possible to carry out work in an apartment, and, at a minimum, it is not recommended. In addition, it is necessary to protect yourself, your loved ones, and property from possible troubles to the maximum extent possible. At any moment something can go wrong, and you need to be prepared for it.

The use of chemical reagents requires high-quality ventilation and the use of personal protective equipment - goggles, rubber gloves and apron, respirator. All manipulations with acids are best done outdoors, on the windward side. It is also necessary to monitor the direction of the wind so that chemical vapors do not blow into the house.

If heating is required, proper fire safety precautions must be taken. Burnishing using oil must be done with a high-quality hood or in the open air. The smoke produced by burning oil is harmful to health and can cause poisoning.

Self-blueing is sometimes the only available method for refinishing the barrel coating. Therefore, when deciding to perform a procedure, it is necessary to study the technology, obtain as much information about it as possible and carefully consider the procedure. Only after this can you begin preparing materials and tools and choosing a workplace. The result depends on the accuracy and preparedness of the master, the thoroughness of all stages of work.