The removal of part of the surface layer of a metal product by a chemical reaction is called etching. This technology has been known to man for several millennia, along with chasing and blackening, it was used to finish metal parts of weapons and household utensils, jewelry and ritual items. Nowadays, metal etching is used in art crafts, for electroplating, for creating images and inscriptions on metal products.

The essence of the method

Before etching, on those parts of the metal surface that should not be etched, a protective coating is applied that is resistant to the etching substance (mordant).

Next, the part is exposed to an acidic environment or immersed in a container with an electrolytic liquid. The longer the part is processed, the greater the layer of metal is corroded by the aggressive environment. Metal etching can be carried out in several stages, this is the so-called multilayer etching.

Etching of images on metal is carried out both in industrial and at home conditions.

Metal etching methods

Based on the materials used to corrode the metal layer, there are such methods of etching metals as:

• Chemical (liquid). Acid solutions are used. It does not require complex equipment and expensive materials. Vapors that are harmful to health are produced during operation.
• Electrochemical. An electrolyte solution is used and an electric current is passed through it. It is characterized by a higher speed of the process, more accurate execution of the details of the pattern, economical consumption of the working fluid. Does not produce harmful fumes
• Ion-plasma (dry). The surface layer is evaporated by an ionized plasma beam. Used in the production of microelectronic components.

The ion-plasma method requires high-precision and expensive equipment and is used only in industrial production. Liquid method, electrochemical metal etching and even electrochemical engraving are available at home.

With the help of galvanic etching, you can independently make a printed circuit board that is almost as good as an industrial one.

Metal galvanic etching

The galvanic etching method compares favorably with the liquid etching method because it does not require the use of acids that produce harmful fumes. Depending on the workpiece material, different electrolytic solutions are used:

• Steel and iron - ammonia and iron sulfate
• Copper and its alloys (bronze, brass) - copper sulfate
• Zinc - zinc sulfate.

To carry out the process at home, you will need:

• Electroplating bath made of non-conductive material.
• Power supply for 5 volts DC.
• Metal cathode (from the same metal as the workpiece.)
• Wire hangers for workpiece and cathode. The workpiece should not touch the walls or bottom of the tub.
• Two conductive rods longer than the tub.

One rod is connected to the negative terminal of the power supply and the cathode is hung on it.

The other rod is connected to the positive terminal and a product is hung on it, which will serve as the anode.

When voltage is applied, the process of electrolytic transfer of metal from the product to the cathode begins. It will occur from areas of the surface that are not covered with a protective varnish.

Artistic metal etching

Artistic etching of metal is carried out both by galvanic and liquid methods.

Masters of folk crafts and just home craftsmen receive with its help highly artistic images on cold steel and firearms, all kinds of forged and cast utensils. For craftsmen who make author's hunting and household knives, etching has become an almost indispensable element of decoration. Hunting scenes, Arabic, runic or abstract geometric ornaments are especially popular. Many craftsmen combine metal etching with bluing, giving the pattern a bluish, black or yellowish tint.

To transfer images, both the method of coating the part with varnish and glossy paper are used. Another method is also used - gluing the part with tape. The lines of the pattern are scratched with a hot needle, after which the adhesive tape is carefully removed from the areas to be etched with tweezers. The remains of the adhesive mass must be washed off with a solvent.

Before pickling, the part must be thoroughly degreased.

Metal surface preparation

Before etching, the surface must be prepared. This will ensure:

• High process speed
• removal of metal in an even layer.

During surface treatment, all mechanical and chemical contaminants are removed from it. A warm soapy solution is used for it, any detergent will do. After the surface has dried, it must be wiped with a rag soaked in a solvent or degreaser. This will remove residual liquid and oil films.

Chemical processing is well combined with mechanical:

• mirror polishing
• sanding. Used when polishing is not available. It should be ensured that the skin moves in the same direction all the time and the traces of it are strictly parallel.

Machining will significantly improve the appearance of the product after etching.

drawing

There are several methods for this operation. All of them are united by a common principle: protecting part of the surface from the corrosive action of the mordant, and distinguishes between the substance used to apply the pattern.

Nail polish

Popular and affordable way. Has some disadvantages:

• The high viscosity of the varnish makes it impossible to draw fine details and fine lines.
• Requires a steady hand and skill in drawing.
• It is very difficult to correct erroneously applied details.

Primer or bituminous varnish

The primer GF 021, XV 062 or bituminous varnish is used. First, the entire etched product is covered with the substance. Next, with a thin pen or marker, the contours of the drawing are transferred. From a thin wire or soft alloy rod, a needle should be made by sharpening the end of the wire.

Those areas of the image that should be etched are scratched to the metal. Care must be taken to ensure that the primer does not chip off.

Glossy paper

In addition to glossy paper (you can buy it at art supply stores, or you can simply cut out a sheet from a magazine), you will need a laser printer, an imaging application, and an iron. The image of the picture should be mirrored and printed in full size. The image is applied to the surface and ironed several times. After the workpiece has cooled, the paper is washed off with warm water, and the toner remains on the surface of the part. The back and side surfaces that are not subject to etching must be protected with varnish or plasticine.

The main advantage of the method is that you can accurately transfer the smallest details of the image.

The main disadvantage is that you can only work with flat or cylindrical workpieces in this way. The method is very popular in the manufacture of printed circuit boards.

Steel Pickling

In addition to artistic metal etching, which allows obtaining exquisite images on steel surfaces, steel etching is also used to remove scale and oxide films. In this case, it is necessary to carefully observe the requirements of the technological process in everything related to the concentration of pickling solutions and the exposure time of the part in the pickle or in the electrolyte bath. Overetching during such an operation is highly undesirable.

When pickling steel, both liquid and electrochemical methods are used. Pickling is prepared on the basis of strong acids, such as hydrochloric or sulfuric. Particular attention should be paid to thorough degreasing of the surface. A missed oil or grease stain can render the workpiece unusable. To protect parts of the workpiece that are not subject to etching, I use varnishes based on rosin, turpentine, and tar.

These components are highly flammable, so when working with varnish, you should be especially careful and careful. At the end of etching, the unetched parts of the workpiece are cleaned of the protective varnish with a solvent.

Picklings used for steel

Nitric acid is very popular among home craftsmen - picklers. It is used as the only basis for pickling, and mixed with tartar or salt. A metal pickling solution based on a mixture of nitric and hydrochloric acid is very reactive and must be handled with extreme care.

For the treatment of hard and special steel grades, mixtures of nitric and acetic acid are used. The processing is carried out in two stages. First, a special preliminary dressing is prepared - glyphogen, which is a mixture of water, nitric acid and ethyl alcohol. In it, the part is kept for several minutes. Next, the workpiece is washed with a solution of ethyl alcohol in distilled water and dried thoroughly. After that, the main etching is carried out.

Sulfuric acid solutions of medium concentrations are used for pickling cast irons.

Pickling of non-ferrous metals

Based on their atomic weight and the physicochemical properties of the substance determined by it, for each metal and alloy they select their own mordant that best affects it.

Both pure copper and copper alloys are pickled using sulfuric, hydrochloric, phosphoric, and nitric acid. Chromium or nitrogen compounds are added to the solutions to increase the reaction rate. At the first stage of etching, scale and oxide film are removed from the workpiece, then proceed to the actual etching of the metal. Care must be taken when pickling copper at home.

Aluminum and alloys based on it are distinguished from other metals by the fact that not acidic, but alkaline solutions are used for their etching. For molybdenum, alkaline solutions based on caustic soda and hydrogen peroxide are also used.

Titanium stands even more apart - at the first stage of preliminary pickling, alkali is used, and at the main stage, acid is already used. For titanium, I use the strongest acids - hydrofluoric and concentrated sulfuric and nitric. Titanium blanks are pickled to remove the surface layer of oxides immediately before being electroplated.

To pickle metals such as nickel or tungsten, an aqueous solution of hydrogen peroxide and formic acid is used.

PCB etching

The blank for the printed circuit board is a textolite sheet, coated on one or both sides with a layer of copper foil. The purpose of etching printed circuit boards is to create conductive traces of copper foil exactly according to the drawing. The tracks are covered with a protective varnish, the rest of the foil is removed by etching.

At home, it uses several methods:

1. Ferric chloride. The reagent is purchased at a chemical supply store or made independently. Iron filings should be dissolved in hydrochloric acid. Before use, the solution should be kept until the iron is completely dissolved and mixed thoroughly.
2. Nitric acid.
3. An aqueous solution of sulfuric acid mixed with hydrogen peroxide tablets.
4. Copper sulphate with the addition of hot water and sodium chloride. This option is the safest, but also the longest. Throughout the entire process, the temperature of the pickle must be maintained at least 40 ° C, otherwise the pickling will last for many hours.
5. electrolytic method. You should take a dielectric container (cuvettes for developing photographs are well suited), fill it with a solution of sodium chloride, place a board and a piece of copper foil there, which will serve as a cathode.

After etching with a liquid method, the board should be thoroughly rinsed with a solution of soda to extinguish the remaining acid.

Pickling process for other materials

In addition to metals, other materials are subjected to etching operations. Glass etching is most common for decorative purposes. Etching is carried out in vapors of hydrofluoric acid, the only one capable of dissolving glass. At the stages of preparation, a preliminary acid polishing of the surface of the product is carried out, then the contour of the future image is transferred to it. Protective coatings for glass are made from a mixture of wax, rosin and paraffins. After applying a protective coating, the workpiece is dipped into a pickling container.

The use of hydrofluoric acid creates a beautiful matt structure on the surface. To obtain a smooth, transparent surface, concentrated sulfuric acid is added to the pickling mixture. To obtain a relief, deep pattern, the operation is repeated.

Pickling Safety

In metal etching, extremely chemically active substances are used - strong acids, alkalis and their solutions. If handled incorrectly, they can cause serious bodily harm and significant property damage.

Therefore, when working with them, special precautions must be observed and the safety rules must be strictly observed during work:

• Work is carried out only in the presence of good ventilation, preferably a fume hood.
• It is mandatory to use personal protective equipment: rubber gloves and an apron, thick industrial clothing, a respirator, a protective face shield.
• Do not place jars with acids and alkalis on high shelves and cabinets.
• During the dilution of acids, ACID is poured into WATER, and never - water into acid.
• When working with an acid, have a soda solution on hand, and when working with an alkali, a weak acetic solution to wash areas of the skin that accidentally got drops of the solution.
• When working with the galvanic method, before starting work, carefully inspect all used electrical equipment for the absence of mechanical damage and the integrity of the insulation.
• Have a proper fire extinguisher handy.

In case of skin contact with pickling solution, immediately wash the affected area with an appropriate neutralizing solution. If acid or alkali splashes on clothing, it should be removed immediately.

If the pickling solution gets on the mucous membranes, you should immediately seek medical help. Delay in such cases can cost health or even life.

Artistic electrochemical metal etching- one of the methods for applying a pattern to metal products (amulets, knives, blades, etc.), compared to engraving, it is less painstaking and takes less time. In this article, you will learn how to decorate the blade of a knife.

Step 1

Let's start by creating a sketch, which we will transfer to the knife blade. You can choose any theme of the sketch - see what other blades have, come up with your own, transfer some drawing, etc. - it all depends on your fantasy and imagination.

After you have chosen a pattern, you need to transfer it to the blade. To do this, place the knife blade in the scanner, scan and open the scanned image in a graphical editor, outline the outlines of the blade; apply the selected pattern, image and edit it. The resulting sketch should be duplicated in a mirror image and printed.

Step 2

Take a knife blade and cover it with varnish, the varnish can be diluted with a nitro thinner, so the varnish dries faster and apply to the blade with an airbrush or brush. We use varnish, because. it retains plasticity during the day and does not crumble.

We cut out the sketch to make it easier to fit it to the blade, "blacken" the back side with a pencil and attach it to the blade with masking tape.

Step 3

We scratch the pattern on the surface of the varnish with the help of scrubbers with different sharpening. Important: do not damage the blade with a scrubber, otherwise it will be scratched.

Step 4

As a power source, you can use a variable transformer, for example, from a toy railway (voltage limit - 12V). Heat-shrinkable cambric serves as insulation. Flannel: copper/brass plate - approx 100/7mm.

Metal etching begins with the fact that we put the fabric on the plate and soak it all in saline. After that, we begin to poison - with a quick touch, you should not hold it for a long time, because. varnish may overheat. When the drawing has a finished look, turn off the machine and wipe the blade with a solvent.

This method of metal etching is good because it is easier to control the process, unlike etching in the vessel as a whole, it is enough to go over the drawing several times.

You can transfer a beautiful and author's drawing to a knife blade at home, but it is very important to observe safety precautions and the principle of drawing a drawing. If you skip these points, at best, your drawing will not work out or you will ruin the knife, at worst, you will get burned. So, all the subtleties and details of how to make drawings on metal by etching, further.

materials

For work you will need:

• • knife with a collapsible handle;

• • iron chloride;

• • distilled water;

• • Plastic container;

• • varnish, vinyl sticker or electrical tape;

• • acetone;

• • cotton pads;

• • plastic tweezers or dental floss;

• • latex gloves;

• fine-grained sandpaper.

Step 1. Completely disassemble the knife, leaving only the blade for further work. Leaving the handle, you risk ruining it during operation.

Step 2. Treat the knife blade with acetone. To do this, soak a cotton pad in it. Wipe the surface carefully so that your fingers do not touch the metal. It is important. If the blade leaves natural oil marks from contact with the skin, the design will be spoiled.

Step 3. Create a drawing template on the knife blade. Those parts that should remain intact, cover with a vinyl sticker, electrical tape, or paint over with quality nail polish. Apply a protective coating to the joints of the blade parts if it is a folding pocket knife. The chemical solution, hitting this part, will hopelessly ruin the product and you just have to throw it away.

Step 4. Put on rubber gloves. In a plastic container, mix distilled water and ferric chloride in equal proportions. Dilute the pickling solution in a well-ventilated area. It is caustic, as are the vapors that will be released during the reaction of the interaction of the composition with the metal.

Step 5. Using dental floss or plastic tweezers, lower the prepared blade into the solution container. We recommend doing this at the following intervals:

• • 20 seconds - metal in solution;

• • 10 seconds - let the solution drain from the blade;

• • 10 seconds - rinse under running water;

• 10 seconds - let the water drain.

This frequency will allow you to adjust the intensity of the resulting pattern. During the etching process, do not touch the part with bare hands, you will get burned.

Step 6. If you only need to etch one side of the knife or transfer a small pattern, do it differently. After mixing the solution, soak a cotton pad in it and attach it to the desired area of ​​\u200b\u200bthe knife. Hold the sponge for 10-30 seconds. When the metal reacts with ferric chloride, the disk will begin to turn dark. After that, also rinse the blade with running water and repeat the procedure if necessary.

Hi all! I will show you a method of electrochemical engraving, with which you can transfer a drawing printed on a laser printer to a knife, cleaver, or any other metal surface. I will transfer the drawing from the computer to the spatula for clarity of the process.

Search for a picture

Printing a pattern

Translation of the picture into metal

Electrochemical etching of the pattern

• - water 50 ml.
• - salt, ordinary kitchen - half a teaspoon.

The result of transferring the pattern to metal

Afterword