How to polish iron at home. How to polish stainless steel to a mirror at home - methods and expert advice

Polishing is the final process of manufacturing a part, carried out using various methods in order to remove a minimum layer of metal to achieve a mirror-like shine on surfaces. These are interrelated physical, chemical, electrical influences, the choice of which depends on the type of material, the tool used and characteristics external environment. The required quality is achieved by replacing abrasives and methods of exposure. Polishing time depends on the initial quality of the metal.

GOST requirements for metal polishing

Requirements for the quality of metal and coatings are defined in GOST 9.301-86. The surfaces should be free of shells, pores, rust, cracks after grinding, scale, and burrs. To the degree of gloss regulatory requirements No.

At enterprises involved in metal processing, input control surfaces. If necessary, the following is carried out:

• treatment with compressed air containing abrasive (steel shot) (rust and scale are removed);
• treatment with metal brushes to remove oxides and etching sludge;
• degreasing heated in organic solvents (chlorinated carbons) to remove grease;
• degreasing in alkali solutions (removal of mineral oils);
• degreasing in electrolyte (electrochemical).

At home, surfaces are wiped with a solvent, processed with a file or grinder with a disk with the appropriate grain size.

Metal polishing class

The polishing class is determined by the surface roughness (the height of the unevenness in microns) of a particular part. The roughness corresponds to the area of ​​use. There are 14 cleanliness classes in total, which are designated in the drawings by an equilateral triangle. Numeric values roughness after metal polishing is specified in GOST 2789-59.

Metal polishing class

In industry, special instruments are used to measure the height of irregularities: profilographs and microscopes. At home, roughness is determined “by eye”.

Existing methods of metal polishing

The most common methods of polishing metal:

• mechanical (abrasive);
• chemical (pastes, solutions);
• electrochemical (in electrolytes);
• ultrasonic.

Mechanical polishing of metal can be dry or wet.

The process can be carried out:

• manually;
• in semi-automatic mode;
• automatically.

Important! At manual processing you can monitor the process and influence the result. Reach High Quality and performance is impossible.

A semi-automatic machine requires special equipment and a qualified specialist. Processing is carried out on metal polishing machines; technological parameters are changed manually. With automatic processing in mass production, human intervention is not required. The work is carried out very quickly and with high accuracy. The volume of defects is minimized.

Manually polish small parts at home. Apply the paste to a cloth and rub the surface in a circular motion. For surfaces large sizes Most often, grinders (grinders) or drills equipped with attachments of various grain sizes are used.

You can install various attachments on the disk. If the nozzle is made of felt or fabric, it is moistened with paste. Professional tools are used in auto repair shops, as they allow you to process fairly large surfaces. On small businesses When processing metal, machines equipped with polishing belts or felt (cloth) wheels are used.

Mechanical methods also include abrasive technology for polishing metal in vibrating drums filled with dry abrasive or solution. Rotation and vibration can quickly reduce roughness. If the method is dry, then the solution is replaced with oak or ash sawdust, pieces of felt or suede. If a solution is used, then in addition to polishing steel balls, alkali can be added to it (for example, a solution laundry soap), speeding up the process.

But mechanical polishing has a number of disadvantages:

• there is a possibility of the introduction of abrasives into the metal structure;
• high costs for installations and resources;
• processing consists of several stages;
• the process is difficult to manage;
• requires significant manual labor and time.

Important! Chemical polishing has a higher potential, especially when it comes to elements of decorative finishing of premises made of various alloys or expensive metals.

When using this method, metal products are immersed in solutions of a certain temperature. When chemical reactions occur, the roughness melts within a few minutes. Manual labor Almost no, no power tools or equipment for polishing metal are required. The surface is processed evenly, the configuration of the part does not matter.

But there are also disadvantages. A mirror shine is not achieved (the surface is rather matte), the solution needs to be changed frequently, it is quite aggressive (most often it is an acid). Work can only be carried out in special clothing; the room must be equipped with a high-quality ventilation system.

During electrochemical polishing, parts are also immersed in a solution, but an electric current is passed through it. Since the surface is uneven, the oxide film is thicker in microcavities. The solution processes smooth parts of the surface with a thin layer of oxide faster. At the end of the process, the surface is perfectly smooth. A small investment of time makes it possible to increase productivity.

The disadvantage is high energy consumption. If the surface is rough, mechanical grinding is required. It is necessary to carefully monitor the quality and temperature of the solution, and current density. Solutions are created from acids, so safety regulations must be followed. To reduce costs, it is advisable to pre-process the material mechanically.

On large enterprises They are trying to automate and robotize polishing. This can be done using ultrasound, which increases productivity by 30 times and eliminates the need to purchase wheels and pastes. Energy consumption is lower than when using chemical or electrical chemical method.

Metal polishes

The technology of manual metal polishing requires the purchase of equipment (drills, grinders) and various attachments.

The main means for polishing metals mechanically are various pastes containing silicon, zirconium or titanium carbide, diamond chips, and chromium oxide. Solid pastes must be diluted with oil. The costs are high, since the process consists of several stages, each of which requires different attachments.

If a chemical or electrochemical method is used, large containers and acids are needed for preparing solutions, and special clothing. Nitric, hydrochloric, sulfuric, phosphoric acid, glycerin, and benzyl alcohol are used. For household These are quite expensive purchases, so chemicals are used only in enterprises.

Metal polishing machines

All polishing machines are divided into 2 groups: with wheels and belts. Belts and wheels consist of abrasives; the selection takes into account the requirements for surface roughness after processing. The equipment is semi-automatic or automatic. Automatic machines can become part of lines used in mass production.

Any machine is equipped with a bed (platform) that does not change position during operation. An electric motor is mounted on the platform, driving the shaft. You can work with sharpening abrasives and wheels. The sharpening angle is adjusted manually or automatically. Some designs are equipped with a water tank necessary for cooling.

Machines available for processing raw materials (steel sheets, aluminum, brass, profiles) and finished products:

• ship fittings;
• plumbing equipment;
• metal cornices and railings;
• door handles, parts of candlesticks;
• bicycle parts;
• tables and chairs;
• mufflers for motorcycles and cars.

The power of industrial models is 700-950 W, they are connected to a 220 V network. The rotation speed is 90-150 rpm. The adjustment is made depending on the characteristics of the material being processed and the wheel format. At the first stages of processing, large circles are used, small circles are used for finishing. The package includes a cable and extension cord. During work, tools for measuring angles, stabilizers, and pastes may be required.

Polishing the metal will significantly improve the aesthetic appearance of the product. If it is not possible to turn to professionals, then you can polish it yourself, at home, the main thing is to follow the technological process.

The process of polishing to a mirror at home

There are several proven methods for polishing metal at home. One of them is chemical (without the use of mechanisms). It does not require much effort, the main thing is that it follows safety requirements. Polishing metal at home using a chemical method occurs in the following order:

1. Sulfuric acid is diluted with water in a ratio of 1:20. The volume of the resulting mixture should be sufficient to completely cover the item being polished;
2. Dip the object to be polished into the resulting solution for a few minutes, and, after removing it, rinse it in running water. Next, place it in a container filled with sawdust;
3. We lower the metal object dried in sawdust for 2-3 seconds. nitric acid, after which we rinse thoroughly again;
4. After the next drying in sawdust, carefully wipe the metal.

After such simple procedures, the metal object will look like new. A smooth and shiny surface will be perceived by the eye as a mirror.

TIP: Before putting a metal item into acid, you need to remove all elements made from other materials from it. Acid can have a detrimental effect on other materials and destroy them.

One of the most popular types of home polishing of metals is processing using GOI paste. This paste was created in the last century and is successfully used to this day. Initially it has a solid form and comes in varying degrees of granularity. For better application, it is recommended to dilute it with a few drops of machine oil.

For hand polishing of soft metals, it is recommended to use a soft flannel cloth with a fine-grain paste applied to it. Ferrous metal can be polished with a piece of tarpaulin or denim with coarse pasta. To get results faster, instead of a rag, you can use a felt circle attached to a hand drill, or a small wooden block.

Required equipment and chemicals

For getting good result at home you will have to spend a little money and stock up on some chemicals, devices and mechanisms. Depending on the method by which you will polish the metal to a mirror shine with your own hands, you will need several items from this list:

• Sulfuric acid;
• Nitric acid;
• Water;
• Sawdust;
• Paste GOI;
• Felt circle;
• Drill;
• Wooden block;
• Textile.

Polishing process

Polishing metal to a mirror shine at home is a rather lengthy process; the main thing here is not speed. If you carry out the process (mechanical) without the use of electrical assistants (after all, some metal objects can be “wiped”), then you should carefully and for quite a long time, with extreme caution, “wipe” every square centimeter of the product.

Advice! For items with indentations, you can use an old toothbrush coated with GOI paste. It is convenient for her to reach hard-to-reach places.

Safety precautions

When using a chemical polishing method, be sure to use special gloves, respiratory protection, and special utensils that do not react with acid. Polishing metal to a mirror shine with a grinder or drill should be carried out using eye protection. And most importantly, you must strictly adhere to technological process. Must always have on hand medical kit, with which you can provide first aid before the arrival of the ambulance, although it is advisable to prevent such cases.

Result

Grinding and polishing of metal at home, carried out in compliance with all technical requirements, is capable of completely restoring the appearance of a metal object. With minimal financial costs and a certain skill, you can achieve high results.

If you need to compare your work with the ideal result, you can always watch a video on the Internet - “Grinding and polishing metal at home”, where you can find lessons on in various ways polishing They tell in detail about all the nuances of polishing metals at home.

Surfaces metal products they are trimmed not only to make them beautiful appearance, but also to protect against rusting, corrosion by acids, alkalis, etc. In one case it is enough to file the product, in another it is necessary to bring the surface to a shine by grinding and polishing, in the third it is necessary to cover it with paints and varnishes, all this can be done yourself at home.

Fig. 1. Finishing of metal surfaces: A - sanding; B - grinding with a file; B - grinding of round products; G - polishing with paste.

After processing metals with a file, more or less deep marks from the notch teeth always remain on them. To make the surface cleaner, smoother and even shiny, it is sanded and polished.

METAL GRINDING

At home, metals are polished with emery cloths after carefully treating the surface with a personal file. To make the skin comfortable to hold, it is wrapped around a wooden block (Fig. 1, A) or a wide file; The ends of the skin are held with the thumb and forefinger of both hands. Convex cylindrical surfaces can be sanded by wrapping sandpaper around them.

First, the surface is processed in different directions, with coarser, coarse-grained skins, then with finer ones. The final grinding is carried out in one - longitudinal - direction using sandpaper with the finest grain. When grinding, the product must be held motionless.

METAL POLISHING

A mirror-like shine is imparted to metal products by polishing. Without preliminary grinding, only surfaces that have been carefully processed with personal and velvet files can be polished. The file should be rubbed with chalk. The surface is first processed across the strokes on it. When the strokes along and across are the same, the direction is changed by 90° and this is repeated several times. The surface treated in this way, as well as the grinding surface, is polished with special polishing pastes.

The industry produces polishing pastes under the GOI brand. They consist of fine abrasive powders (chromium oxide, iron oxide, etc.), soft plastic substances composed of wax, stearin, kerosene and other materials. GOI pastes come in coarse (dark, almost black), medium (dark green) and fine (light green). First, they polish with a coarse paste, which makes the surface matte, then with a medium and, finally, a fine paste, bringing it to a mirror shine. The paste is applied to a felt swab, cloth or linen cloth and rubbed onto the surface to be polished.

You can make your own polishing pastes. For polishing steel products, the following composition is recommended (in parts by weight):

Stearin - 32

Beeswax - 6

Technical lard - 5

Lead oxide - 3

Chromium oxide - 80

For polishing and glossing brass and nickel-plated surfaces, use pastes of the following composition (in parts by weight):

Stearin - 5

Technical lard - 1

Chromium oxide - 14

The polished surface is wiped with a rag soaked in kerosene, and then dry with a clean rag.

Typically, metal polishing is done when color has been lost, rust has appeared, or some tarnishing has occurred. This labor-intensive operation is performed only on a sanded surface. Its main task is to give the product a mirror shine. Any room that has well-polished metal objects will appear most attractive. Such things will play with light, like a mirror. However, to make this a reality, you will need a special metal polishing paste or powdered substances that are mixed with a viscous solution.

At the first stage, metal polishing involves cleaning from various contaminants. To do this, use a soft cloth soaked in water. You can also use them to remove not only dust, but also stubborn dirt. It is enough to apply just one drop of the product onto a napkin. Next, the metal product must dry so that the paste or powder is successfully distributed over the surface. A soft towel or hair dryer will help speed up the drying process. As for polishing agents, they can be purchased at almost any hardware store.

Next, the metal itself is polished. Apply a small amount of paste to a soft cloth. This is quite enough for a not very extensive surface. The paste is rubbed from both sides to the center. Not a single centimeter of surface should remain without it. Using this method, it is quite possible to bring a metal product to a mirror shine. To eliminate gaps and achieve maximum results, it is necessary to reapply the polishing agent. If you do this every six months, then all metal objects will be in perfect condition and sparkle in the sun.

You need to know that polishing precious metal requires the use of a special polishing pad made of hematite or high-quality steel. This tool is a rounded working part with a wooden handle. You can make it yourself if you take rollers and balls from bearings. Thanks to this process, the treated surface acquires a rich shine. The polishing pad moves only in one direction, but after finishing the work is repeated in the transverse direction. In this way, metal objects gain their true beauty.

However, in order to make any metal object, metal comes to the rescue, allowing you to achieve efficiency and a high level of productivity. IN Lately more and more attention is being paid to it, since it has managed to prove its worth in practice. The plasma arc, which performs the main function, arises as a result of the use of technical gases. Argon and helium are especially popular, as they provide high-quality protection in the welding zone.

There are many options for polishing a knife to a mirror shine. Some of them are aggressive, others are softer and gentler. Polishing can be carried out using ordinary natural stones, wet and dry paper. The work is carried out as carefully as possible using special pastes of domestic and foreign production.

Manual polishing

In the past, craftsmen from all over the world did not have specialized equipment, but they performed their work efficiently. But how to polish a knife without special equipment? After heat treatment, craftsmen used natural abrasive materials (such as stone or a metal device).

Polishing manually Helps achieve a perfectly smooth surface. In this way you can get the correct shape of the blade. Even using a special polishing and grinding device, it is not always possible to achieve a similar effect. It is believed that hand polishing is the final finishing of a knife.

How to polish a knife at home correctly using the manual method? Before proceeding to manual processing, it is necessary to polish the knife on a tape, the grit of which should not be less than 320. Using sandpaper, scratches are first removed. They may appear on the surface of the product after machine processing.

Features of sanding

How to polish a knife to a shine using sandpaper? The first step is to polish at an angle of 90 degrees. In this case, irregularities may appear on the surface of the knife. This may occur due to the accumulation of grain on the surface. Sometimes the unevenness cannot be removed with slightly abrasive paper. In this case, you need to move on to coarser material again.

To carry out the work as efficiently and carefully as possible, it is necessary to ensure quality lighting, and the whole process must be carried out under a magnifying glass. When all the shortcomings have been eliminated, you can move on to standard processing again.

During the polishing process, you can use different types of sandpaper. The main thing is that the transition between grain sizes is insignificant. First, the polishing is carried out with a material with a grain size of 600, then it is increased to 800. You can stop, or you can continue polishing with a material with a value of 2000.

Abrasive stones

How to polish a knife blade using a stone? Abrasive materials of this type have different grain sizes. The most popular indicators are 320, 400 and 600. To properly level the knife, experts recommend using Indian bench stones.

This simple device is still used today, although it was first used in the Stone Age to remove excess material from weapons. At that time, not only stones were used, but also sand and soil.

For polishing, only those stones were used that were harder in structure than a knife. Some craftsmen prefer a square shape, while others like a round one. The most popular stone for polishing is sandstone.

How to use stones correctly?

When polishing, rough and thin stones are used. The coarse material has a grain size of 80, and the fine one - 15. You can examine the structure of the stone in detail under a microscope. How to polish a knife this way? A rough stone is used to remove scratches that most often appear on a knife after a file. Another type of stone is usually applied before heat treatment. To prevent the surface of the stone from clogging, it must be periodically moistened with water.

To understand how to polish a knife to a mirror shine, you need to pay attention to Arkansas stones. Their grain size can reach 1000. This material is ideal for finishing. If polishing is just beginning, it is better not to use such stones, as they work slowly. You can achieve a mirror shine using Japanese wet stones. In addition, you can find on sale not only natural, but also fairly high-quality artificial stones.

Quick polishing by hand

You can also polish a knife by hand. Movements must be made along the blade. It is this tactic that helps get the job done as quickly as possible. Often double-sided is used for these purposes.

The blade of a knife can be polished thanks to rapid friction. This method has many disadvantages. The surface of the knife is imperfect; rough undulations and scratches can be seen on it.

Such defects can be eliminated, but to do this, all scratches must be in the same direction. After rough processing, it is necessary to prepare a small piece of leather and a special polishing compound, with the help of which the finishing process is carried out.

Application of dry and wet paper

Polishing work is carried out with both dry and wet paper. The material should be slightly damp so that it does not deteriorate or become greasy during the polishing process. For a certain type of work, you need to use only dry paper.

How to polish a knife at home using paper? To do this, it is recommended to purchase a whole set, which usually consists of fifty sheets. This option is considered the most economical. It should be borne in mind that waterproof material is more durable than non-waterproof material. Paper treated with crushed silicon carbide is ideal for polishing metal products.

To make it convenient to work with the material, you must proceed as follows:

• fold the paper in half lengthwise;
• the material is secured with clamps to a small steel plate;
• If you fold the paper in half and place it on the plate, it will not slide off while you work.

Experts recommend making small templates and blanks first. If the master needs to treat the area near the handle, small strips are not folded, but are applied across the entire width. To prevent the tape from tearing during the polishing process, the back side of the material is covered with masking tape.

Mirror processing

Knives of any type look amazing when they have a perfect mirror surface. But how to polish a knife blade at home so that it has such an excellent surface? Each master uses his own polishing methods. Whatever method is used, the ideal surface of the knife indicates a high level of skill.

Often, to achieve an ideal surface, the product is first polished by hand to 800 grit, and then a special grinding wheel is used. Such processing is necessary in order to remove all irregularities and prepare the knife for final mirror polishing.

You need to work with grinding wheels carefully. Too high a speed may damage the product. In most cases, the grinding wheel should have a soft surface. For some types of work, hard is used. It is also dangerous to work with loose polishing wheels. They have one unpleasant feature - they often grab blades and some other parts of the product.

Security measures

Many people think about how to polish a knife at home safely. The most important condition is not to install the polishing machine directly on the workbench. The fact is that during work, the polishing wheel often catches the blade, which can bounce off and harm the master.

Experienced craftsmen who often polish and grind knives additionally install special protections on polishing wheels. In this case, residual material in the form of polishing compound and dust will fly onto the floor and not onto the master.

Using GOI paste

This method well known to craftsmen who make knives. How to polish a knife with GOI paste? To do this, you need to choose the appropriate type of polishing material, which depends on the type of metal. In addition, you need to remember several polishing rules.

GOI paste has been used for over a hundred years. It is used to polish metal, plastic, ceramic and even glass products. Previously, the paste was presented in green color and was made from chromium oxide. However, this substance was found to be toxic, and at the moment the paste is made from aluminum oxide. The paste is available in red and white.

Types of pasta

Previously, there was only one type on sale. But now specialists have much more choice. The paste is produced with different abrasiveness:

• No. 4 - is used specifically for rough work that is carried out on initial stage polishing;
• No. 3 - helps to achieve a matte surface;
• No. 2 and No. 1 are used for finishing.

Green paste is sometimes found on sale, but it is difficult to find. Previously, such polish was produced both in liquid form and in the form of bars. The two types of paste are identical in effectiveness. Green has one advantage - low cost.

Preparation for polishing

Before you understand how to polish a knife, you need to familiarize yourself with the preparation for this process. It must be remembered that the paste has many particles, thanks to which polishing is carried out. Sometimes they can accumulate and damage the product. To prevent this from happening, you need to take a small amount of the substance and rub it on an old piece of metal. In this way, large pieces of grain can be broken, otherwise the surface of the knife will not be polished, but will be scratched.

First you need to take a soft cloth and lightly moisten it in gasoline. In this case, the fabric should be as soft as possible. Flannel is perfect for these purposes. Often the paste is applied directly to the polishing wheel. It cannot be applied to the product itself. The knife should be lightly lubricated with special oil.

How to use the paste?

So how to polish a knife using GOI? When the fabric and paste are ready, you can move on to the main steps. You just need to rub the product with this composition. Do not press too hard on the surface of the knife. Otherwise, there will be small scratches on it.

For the same reasons, it is not recommended to make very sudden movements. The work is completed when the surface of the product is perfectly smooth. While working, you need to stop from time to time and apply a little industrial oil to the knife.

If the surface of the knife has many flaws, in this case you will need to purchase several types of paste. First, the treatment is carried out with paste No. 4, thanks to which deep scratches are removed. After this, move on to number 3, and then to paste No. 2 and 1. The last type of paste helps to carry out finishing grinding and achieve a mirror surface.

At the end of the work, you need to rinse the knife in running water. Experts recommend using kerosene, which can be purchased at a pharmacy, for this purpose rather than water. The knife must be thoroughly dried. Some craftsmen additionally coat the surface of the knife with tsapon varnish. This substance helps prevent oxidation of the material. The last stage is polishing the product with genuine leather.

Knife handle processing

If everything is clear with the blade, then how to polish the knife handle? IN in this case you need to act with extreme caution. For these purposes, use the finest grit sandpaper. You need to act carefully so as not to damage the handle. This is a rather fragile element.

Now about the material. Which one is better to choose to perform this operation? GOI paste will be an excellent polishing agent. But which type should you choose for processing the knife handle? In this case, you need to use paste numbers 1 and 2. To make the handle shiny, it needs to be polished with a small piece of leather.

If the handle is made of wood, additional impregnation is necessary. This will help preserve its original appearance for a long time. Typically, impregnation is carried out using regular or special oil, which is sold in an artist store. In addition, you can simply coat the handle with a protective varnish.

Conclusion

So, we found out how to properly polish a knife. As you can see, there are many ways to do this operation. The main thing is to properly prepare for the procedure and follow the recommendations of specialists. This is the only way to achieve the desired result.