Metal etching by electrolysis. Etching of circuit boards using water electrolysis. Preparing the part for etching

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

The essence of the method

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

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

Etching 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). Acidic solutions are used. Does not require complex equipment or expensive materials. During operation, fumes that are harmful to health are generated.
• 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 design, and economical consumption of working fluid. Does not form harmful fumes
• Ion plasma (dry). The surface layer is evaporated by a beam of ionized plasma. Used in the production of microelectronic components.

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

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

Galvanic metal etching

The galvanic method of etching compares favorably with the liquid etching method because there is no need to use 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:

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

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 that will serve as an anode is hung on it.

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

Artistic metal etching

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

With its help, masters of folk crafts and simply home craftsmen obtain highly artistic images on edged weapons and firearms, all kinds of forged and cast utensils. For craftsmen making designer hunting and household knives, etching has become an almost mandatory finishing element. Especially popular are hunting scenes, Arabic, runic or abstract geometric patterns. Many craftsmen combine metal etching with bluing, giving the design 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. Using a hot needle, scratch the lines of the design, after which, using tweezers, carefully remove the tape from the areas to be etched. Remains of the adhesive mass must be washed off with a solvent.

Before etching, the part should be thoroughly degreased.

Metal surface preparation

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

• High process speed
• removing metal in an even layer.

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

It is good to combine chemical treatment with mechanical treatment:

• mirror polishing
• sanding with sandpaper. Used when polishing is unavailable. You should make sure that the skin always moves in one direction and that the marks from it are strictly parallel.

Mechanical processing will significantly improve the appearance of the product after etching.

Drawing

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

Nail polish

Popular and affordable method. Has some disadvantages:

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

Primer or bitumen varnish

Primer GF 021, XB 062 or bitumen varnish is used. First, the entire product to be etched is coated with the substance. Next, use a thin pen or marker to transfer the contours of the drawing. A needle should be made from thin wire or a rod of soft alloys, sharpening the end of the wire.

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

Glossy paper

In addition to glossy paper (you can buy it at art supply stores, or you can simply cut a sheet out of a magazine), you will need a laser printer, an imaging application, and an iron. The image of the drawing 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 the smallest details of the image can be accurately transferred.

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

Steel pickling

In addition to the artistic etching of metal, which allows one to obtain exquisite images on steel surfaces, steel etching is also used to remove scale and oxide films. In this case, you should especially carefully observe the requirements of the technological process in everything related to the concentration of etchant solutions and the time of exposure of the part in the mordant or in the electrolyte bath. Over-etching during such an operation is extremely undesirable.

When etching steel, both liquid and electrochemical methods are used. The mordant is prepared on the basis of strong acids, such as hydrochloric or sulfuric. Particular attention should be paid to thoroughly degreasing 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 you should be especially careful and careful when working with varnish. After etching is completed, the unetched areas of the workpiece are cleaned of the protective varnish with a solvent.

Mordants used for steel

Nitric acid is very popular among home picklers. It is used as the only base for mordant, or in a mixture with tartar or salt. A metal etching solution based on a mixture of nitric and hydrochloric acid is very chemically reactive and should be handled with extreme care.

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

For pickling cast iron, solutions of medium concentrations of sulfuric acid are used.

Pickling of non-ferrous metals

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

Both pure copper and copper alloys are etched using sulfuric, hydrochloric, phosphoric, and nitric acid. To increase the reaction rate, chromium or nitrogen compounds are added to solutions. At the first stage of etching, scale and oxide film are removed from the workpiece, then proceed to the actual etching of the metal. Be careful when etching copper at home.

Aluminum and alloys based on it stand out among other metals in that they are etched using alkaline rather than acidic solutions. For molybdenum, alkaline solutions based on sodium hydroxide and hydrogen peroxide are also used.

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

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

PCB etching

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

At home he uses several methods:

1. Ferric chloride. The reagent can be purchased at a chemical 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 tableted hydrogen peroxide.
4. Copper sulfate with the addition of hot water and sodium chloride. This option is the safest, but also the longest. Throughout the entire process, the pickling temperature should be maintained at least 40 o C, otherwise the pickling will take many hours.
5. Electrolytic method. You should take a dielectric container (cuvettes are good for developing photographs), fill it with a solution of table salt, place a board and a piece of copper foil there, which will serve as a cathode.

After etching with the liquid method is completed, the board should be thoroughly washed with a soda solution to extinguish any remaining acid.

Etching process for other materials

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

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

Pickling safety precautions

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

Therefore, when working with them, you need to take special precautions and strictly follow the safety rules when carrying out 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 work clothing, a respirator, and a protective face shield.
• Do not place jars containing acids and alkalis on high shelves and cabinets.
• When diluting acids, ACID is POURED into WATER, and never water into acid.
• When working with acid, have a soda solution on hand, and when working with alkali, have a weak vinegar solution to wash areas of the skin where drops of the solution accidentally fall.
• When working using the galvanic method, before starting work, carefully inspect all electrical equipment used for the absence of mechanical damage and integrity of the insulation.
• Have a working fire extinguisher on hand.

If the etching solution comes into contact with the skin, immediately wash the affected area with an appropriate neutralizing solution. If acid or alkali splashes onto clothing, it should be removed immediately.

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

The basis of the technique is the method of electrochemical etching of metals. Briefly, it is as follows: The part on which the inscription or drawing is made (previously applied with a special varnish) is immersed in an electrolyte solution; it is the anode. That is, the (+) current source is connected to it. The cathode, which is also immersed in the electrolyte solution, is a strip of stainless steel. The (–) current source is connected to it. When the current is turned on, electrochemical etching occurs, that is, the dissolution of the surfaces of the part unprotected by varnish.

The figure schematically shows the principle of the process.

The numbers show:

1. Metal part.

2. Etched area.

3. A layer of varnish keeps the metal unetched.

This is the basis. Now let's look at the whole process in detail.

1. Preparation of the part.

As a rule, it comes down to thoroughly degreasing the surfaces on which the varnish will be applied. Why is this being done? Firstly, the varnish sticks very firmly to the degreased surface, which guarantees that during the etching process it will not be torn off by parts, which will lead to irreparable defects in the form of undesirably etched areas. This can completely ruin the product.

Secondly: if there is a non-greasy area left on the surface to be etched. For example, even your own fingerprint! This fat can act as a layer of varnish, protecting the surface from etching. And then you get an etched fingerprint. This defect is unpleasant, but in most cases it can be eliminated by re-grazing.

And so we will clean the surface from foreign dirt, debris, etc. Be sure to wear rubber gloves so as not to leave fingerprints. And it’s easier to work this way in hot water.

Photo: washing the knife under running water and soap.

Degrease by soaking the part in a solution of soap, washing powder in hot water for some time. Then you need to thoroughly clean the part with a toothbrush (a toothbrush will do) in the same solution. Particular attention to blind (not through) holes. They are very difficult to wash. You can't leave dirt there. Washing is carried out under running water as thoroughly as possible. Don't take off your gloves! From now on, it is generally extremely undesirable to touch the part with hands without gloves, in order to avoid the appearance of the defects described above. If you do touch the part, it is better to repeat the degreasing process. How to check the quality of degreasing? Very simple. Water drains completely from well-degreased metal, leaving no drops or streaks. If drops remain, water sticks to the metal (exact expression), then there is fat in these places. Scrub them with a brush and solution more thoroughly and repeat washing and checking.

Another secret. An ultrasonic bath is used to degrease complex parts that have difficult-to-clean holes, crevices, etc. At home, it can be successfully replaced with a household ultrasonic compact machine. The use of ultrasound significantly reduces degreasing time and improves quality. But in most cases this is not necessary.

Small parts can be degreased by wiping with cotton wool and tooth powder moistened with alcohol. The powder contains soda, which will remove fat. A very quick method of degreasing, but it requires some skill.

Photo: degreasing with alcohol and tooth powder.

2. Preparation of a special varnish.

A special varnish is used to apply inscriptions and designs on metal. The composition and method of preparation have been developed as a result of practical work and, when following these recommendations, guarantee the quality of work. The varnish provides reliable protection of parts of the part from etching and is easily removed at the end of the process. We will need the following ingredients to prepare it:

Tar. The substance is black, fragile. Widely used in construction for roof waterproofing and road repairs. Sold in building materials stores in large pieces of 50 kg. For our purposes, such an amount will not be needed. Therefore, it’s easier to look for a piece of tar at construction sites, ask workers pouring roofs or repairing roads. In such cases, as a rule, fragments remain and are simply thrown away. It is important to find a sample that is clean and free of sand and other debris. The content of foreign impurities is highly undesirable and will significantly reduce the quality of the finished varnish. Main component. The required quantity is almost equal to the volume of the finished varnish.

Rosin. A fragile, amber-colored substance. Made from pine resin. Widely used in soldering electrical products. Inexpensive. Sold in hardware stores, can also be sold as part of soldering kits, together with a soldering iron and tin. The required amount of crushed matchboxes (about 30 cc). Approximately.

Gum turpentine. A flammable liquid used as a solvent for some paints and varnishes. Sold in hardware departments next to paint. Usually in 0.5 liter bottles. One bottle is enough.

As you can see, all three substances are readily available and inexpensive. Also not hazardous to health.

The tar must be crushed (cracked with a hammer) and placed in a metal container with a lid, in which we will prepare the varnish. Add turpentine there and stir to dissolve. You can leave it for a while to dissolve the tar pieces. Rosin is also crushed and mixed with pieces of tar. Although some sources recommend adding rosin to already dissolved tar. The main thing here is to ensure melting and uniform mixing. It is desirable to obtain the viscosity of liquid sour cream. Now you need to heat the mixture for better mixing.

Heating is carried out on an electric stove, at a low heating setting. It is not recommended to use heat on a gas burner due to the risk of fire. I highlight the most important issue of fire safety separately.

Attention! Varnish and its components are flammable!

Do not use open flame sources to heat the varnish and do not cook the varnish near the fire! Fumes from molten tar are also flammable! If grayish-white smoke appears above the varnish melt, this is a signal of dangerous overheating. Do not open the lid! Vapors can flare up at any second even from simple stirring. Immediately and carefully, without jerking, remove the container with varnish from the heated stove and cool. Do not cook varnish in residential areas; it is better to do this in well-ventilated places, as a characteristic odor appears. Just in case, prepare a piece of thick fabric. If your polish catches fire, don't panic! Don't put it out with water! Cover the container with a tight lid or cover the fire with a thick cloth. The flame will go out immediately without oxygen. When extinguishing with water, you can be scalded by water vapor, burning splashes of varnish will fall on the body, clothes and objects, and then burns and a fire in the room are inevitable! Never move away from cooking varnish.

The main reason for all fires is that they forgot the varnish on the tiles and went out to drink tea!

If you take reasonable precautions, you will avoid fire. There are practically no cases of fires at work these days.

Heating with stirring is carried out to a temperature of 60-70 degrees. This ensures that the components are mixed and a varnish with the required properties is obtained. Now the varnish can be cooled and stored in a container with a tight lid. The varnish will thicken slightly as it cools.

Simplified preparation of varnish.

You need to purchase ready-made bitumen varnish. It is also freely available in paint and solvent departments. It is used in everyday life to protect water pipes from rust. The varnish is diluted with turpentine and finely ground rosin is added. Approximately a matchbox of rosin for 0.5 liters of varnish. Stir thoroughly under low heat until completely dissolved. Don't forget about fire safety! Cool and pour into a container for storage.

Before direct use, the varnish is diluted with turpentine to the required thickness. The varnish does not deteriorate during storage for a long time. If it thickens, you can always dilute it with turpentine.

3. Applying a design to a knife (another part).

You will say that only an experienced artist can draw a picture or an inscription. But what about someone who doesn’t have the ability to be an artist? The situation here is not at all hopeless. Even experienced artists resort to simple tricks that can significantly improve the quality and speed of drawing. Using this technique, almost any person (of course, if your hands don’t shake!) can successfully achieve good quality. A little practical experience will greatly increase your confidence in your work.

First you need to decide on the future miniature or inscription. Make a preliminary pencil drawing on a scale of 1:1 (it's called a sketch). At the same time, no one forbids you to cut out a suitable design from a magazine, newspaper, etc. with scissors. You can also run it on a computer, if you are familiar with the necessary programs, set the required scale and print it.

Now let's apply the design to the degreased surface of the knife, details using transfer paper! You just need to use a color translation of yellow, red, white (there is one). The transfer of black and purple colors does not leave marks on the metal.

Photo: The knife is inscribed with yellow transfer paper.

Horizontal lines are also marked for writing straight letters.

Advice from an experienced craftsman: To prevent the design from shifting when copying, secure it and the transfer paper with pieces of tape. Then the drawing is translated using a pencil or pen. The line marks from the transfer paper will allow you to continue varnishing easily and accurately.

4. Painting with varnish.

To draw the future drawing and inscription with prepared varnish, you need to use thin brushes or feathers. By choosing the optimal thickness of the varnish and with a little practice, you can quickly learn how to draw the translated drawing. If you have some experience, you can also freely write with a pen, even without first marking with transfer paper.

Photo: the artist traces the translated inscription with varnish using a brush. Please note: a wooden hand rest is used. A stand in the form of a bench 3 cm high above the table surface. (width 6 cm, length 30 cm). Facilitates precision work and relieves stress, allowing you to work for a long time without fatigue. The stand prevents your hand from touching the grease-free metal surface.

The operation requires some skill and patience. Don't be discouraged if it doesn't work out the first time. You can always easily wash off the varnish using the same turpentine, solvent, gasoline (just use pure unleaded gasoline for nefras or galosh lighters, leaded gasoline is poisonous!) and try again.

Photo: Binocular glasses with 5X magnification.

Photo: The pattern on the knife is painted with varnish. Please note: continuous varnishing of areas not subject to etching has not been completed completely. This is done with the expectation of subsequent surface protection using plasticine!

5. Pre-drying the varnish.

The next technological operation is preliminary drying of the varnish to a semi-solid state. To do this, it is enough to leave the part in a ventilated place for 2-3 hours at room temperature. The varnish will partially dry and thicken.

6. Final elaboration of the drawing.

While applying the drawing with a brush or pen, you may have made some inaccuracies, mistakes and painted over those places that should have been left under the grass. Now you can fix all these defects. Using a sharpened stick made of wood, plexiglass, PCB or a thin metal needle, it is necessary to remove the varnish from excessively painted areas. You also need to clean up the edges of curved lines, making them smoother and more attractive. Trimming the edges of the lines is also important in view of the fact that the layer of varnish at the edge of the drawing is always thinner, and there is the possibility of unwanted etching. By removing varnish from the boundaries of lines, we thereby make the boundary layer of varnish thicker and increase its reliability.

Photo: tools for final elaboration of the drawing. A plexiglass stick, a needle at the end of a stick from an old brush, a fountain pen.

During final processing, an engraving operation is also performed. It involves scratching fine lines using a sharp needle attached to the end of a stick from an old brush. This way you can make very thin etched lines or write an inscription or imitate the knife number.

Removal of grains of excess varnish should be done by blowing off or using cotton wool soaked in alcohol. Alcohol does not dissolve varnish and easily removes debris. If you use turpentine, pure gasoline (galoshes) or any other solvent, the drawing will simply be washed off completely. This way you can delete unsuccessful work results, which is very possible at the initial stage.

Photo: The thin lines scratched with a needle are very clearly visible.

For this operation, it is advisable to use a magnifying glass or binocular glasses.

7. Drying the varnish.

You can finally dry the varnish in various ways. Drying is a very important and responsible operation, the quality of which determines the result of the work.

The most common and reliable method is oven drying. Temperature 100-130 degrees. Drying time - 30-40 minutes. Then cool at room temperature. However, this method is used for large volumes of work. At home, we can recommend drying it in an old electric oven set to the lowest heat setting. Do not use ovens that are used for cooking! The remaining smell will linger for a long time and will make cooking impossible! If you forgetfully exceed the drying time, there may be cases of overdrying of the varnish.

Another way is natural drying. Just leave the part at room temperature in a ventilated place. Usually the varnish dries completely in 3-4 days. Drying is quite high quality, but very long. To speed up the process, tabletop heat fans are used, with the help of which drying occurs in 1-2 hours.

Photo: Drying varnish using a fan heater.

1 - fan heater.

2 - Details.

Then the cold air flow mode is turned on and the part quickly cools down to room temperature. Perhaps this is the only drying method for parts that have elements that are afraid of heating. For example, writing on a knife that already has a handle assembled. You can’t heat such a knife in a drying cabinet; you can simply burn the handle!

A special warning applies to knives in which the handle is attached to the blade using epoxy resin. When heated to 80-90 degrees, the resin softens and collapses. When it cools, it will not harden again. You can work with such a knife only after disassembling it. How to remove the handle? It’s very simple: heat the blade to 80-90 degrees and pull out the handle!

With natural drying there is practically no danger of over-drying the varnish.

A high-speed drying method is possible using an electric stove. The part is held with the help of a heat-insulating device (you can use pliers) above the heated surface of the electric stove 5-10 cm. The method is quite dangerous due to overheating of the varnish and its fire. The end of heating is considered to be the moment the temperature reaches 100-130 degrees. At this temperature, a drop of water falling on a heated part hisses and rolls along the surface. Which can serve as a simple heating indicator. This is then followed by cooling to room temperature. If you overheat a part, you can very easily dry out the varnish.

A well-dried varnish becomes rigid and does not leave a dent when pressed with the tip of the nail.

8. Danger of overdrying the varnish.

If it overheats or takes too long to dry, the varnish becomes too strong to such an extent that it becomes impossible to remove it with gasoline or any other solvent! This varnish turns into a durable coating, which can only be removed mechanically: by sanding with sandpaper or even using sandpaper!

This can very easily damage a part or a knife. Don't forget about the part located in the drying cabinet or above the tile! Better set a timer for reminders!

Forgetfulness is the main cause of dryness and fires!

Don't forget about fire safety rules! All the above precautions remain relevant during this operation!

Carefully inspect the quality of the dried varnish. It is very possible for bubbles to appear due to very rapid heating. They need to be tinted and dried for a short time.

Photo: part after etching; bubbles that arose during drying led to the appearance of undesirable etched spots (highlighted in red). The defect is irreparable.

9. Operation after drying.

Before subsequent weeding, it is necessary to additionally rinse and degrease the part, which is done by lightly wiping with cotton wool moistened with alcohol and a small amount of regular tooth powder. Then finally with pure alcohol. We have already discussed the need for this in the chapter devoted to surface degreasing. You will also additionally check the strength of the dried varnish.

10. Preparing the part for etching.

It is not at all necessary to paint over all other surfaces with the same varnish. It is enough to limit yourself only to the area around the inscription or drawing. For protection, you can successfully use plasticine, polyethylene and other available materials. Plastic lids and packaging for mayonnaise and other products can be very useful, from which it is convenient to cut out the necessary templates. Carefully wrap the knife handle with plastic wrap, securing it with electrical tape and tape. Plasticine, ordinary, for children, will reliably protect metal surfaces from etching. In general, it is necessary to try, if possible, to protect large painted surfaces with an additional layer of plasticine, which will provide additional protection against unwanted mordants. Looking ahead a little, we note that you immediately need to take care of securing the electrode, and the place of fastening also needs to be protected. At this stage there cannot be any specific recommendations; it all depends on your capabilities and the properties of a particular part. The main requirement is to provide hermetically sealed protection for parts not subject to etching.

Photo: the knife is prepared for etching the inscription. The handle is protected by a layer of polyethylene and tape. The blade is protected with plasticine. Only the etched inscription is left open.

Photo: the part is prepared for etching. Protection with plasticine. The wire for connecting the current is clearly visible.

11. Installation for etching.

The general design of the installation can be seen in detail in the diagram. It consists of a direct current source, a vessel (bath) for etching with electrolyte, stainless steel electrodes (cathodes), the part to be etched and conductors connecting the current source to the electrodes.

Let us explain in more detail.

DC source.

In general, the source must provide a constant current of 3-10 amperes; an ammeter that constantly shows the current is required. It is desirable to have protection against short circuits due to negligence, which can be successfully provided by a fuse of the appropriate rating. In practice, there is no need to purchase an expensive current source with a digital display and a built-in timer. An excellent solution is a device for charging car batteries. It is very possible that you have had it in your garage for a long time. And it's inexpensive to buy. Typically, such devices are equipped with an ammeter, a fuse and a current switch. For craftsmen familiar with electrical circuits, we can recommend assembling a homemade rectifier. I note that smoothing capacitors at the output of the current source are not at all necessary; rectified current with ripple is quite suitable. For pulsed current sources, a capacitor is still needed.

Pickling bath.

It is desirable that the bath be made of non-conducting material. For example: polyethylene, plastics, etc. The main requirement: the part must fit freely in the bath completely immersed in the electrolyte. It is possible to carry out the weeding in a metal container, but it is necessary to isolate both the electrodes (cathodes) and the part from electrical contact with each other. Remember that this significantly increases the risk of electric shock! Do not touch the metal bath while the current is on! Such a bath must be grounded. The safest way is still to use non-metallic utensils. Get creative. For example, to weed long blades of swords, sabers, checkers, use a piece of polyethylene pipe with a diameter of 150-200 mm and the required length as a bath. The bottom of the pipe is, of course, capped. Often, for weeding a single copy of a knife, it is quite possible to use a 1.5 or 2 liter plastic bottle of mineral water or beer, having previously cut off the top part. Although the electrolyte is quite harmless, it is still not recommended to use food utensils for pickling.

Electrolyte composition.

A simple solution of table salt is suitable for weeding most modern stainless steels! For a liter of plain (not distillate) hot water, add 3-5 tablespoons of salt and mix thoroughly. Sometimes it is recommended to add 8-10 milliliters of hydrochloric acid (concentrated) to such an electrolyte. Use extreme caution when handling acid! Although in practice, weed works just fine without it.

To pickle rusting types of steel, copper, brass, aluminum, add a tablespoon of copper sulfate to the salt solution. It is sold in hardware departments, fertilizers (bluish-green powder). I note that aluminum will be etched without any current being connected at all, releasing a large amount of heat. The electrolyte may boil.

The electrolyte is relatively harmless to health, you can work without gloves, but there will be stains that are difficult to wash off. After work, you still need to wash your hands with soap and warm water. It is quite possible to flush the used electrolyte into the city sewer, along with a large amount of water. The electrolyte has a limited service life. That is, during the etching process it is saturated with metal salts and gradually loses its properties. Insoluble brown and green precipitates also accumulate and contaminate the drawing and interfere with observing the process. This electrolyte needs to be replaced. Or let it sit and carefully pour, discarding the sediment.

Previously, solutions of strong acids were used for etching without the use of electric current. We don't recommend doing this. This is a rather dangerous and unhealthy process that requires exhaust ventilation; it is necessary to work with glasses and protective equipment. In addition, modern steels are so resistant to acids that it will take a lot of time with no guarantee of results.

And our simple, safe electrolyte copes with any steel!

Electrodes (cathodes, -).

The most suitable material for manufacturing is mild stainless steel. It is used to make dishes, thermoses, water tanks, spoons, and forks. Most often, the electrodes are strips of sheet steel located on both sides along the walls of the etching bath. If the part has an etched pattern on one side, it is necessary to place the electrode opposite the etched surface, otherwise etching with different (uneven) depths is possible, which is a noticeable defect. Accordingly, if we etch two opposite sides of a part (knife) at once, the electrodes should be on two opposite sides. The size of the electrodes (their surface area) is not particularly critical. The main thing is that the electrode must exceed the area being etched, otherwise an uneven etching depth may be obtained. To etch a small inscription on a knife, the author successfully used an old stainless steel tablespoon. (True, then it took a long time to clean it with sandpaper!) The service life of the cathodes is not limited. They do not dissolve during operation, but only become dirty. Metal salts are deposited on them; when brass is etched, a layer of copper is deposited on them.

Photo: brass etching. A layer of copper appeared on the electrode after 15 minutes from the start of the process, which can be easily removed by washing in hot water. After which the etching continued.

U The next step is to wash them with hot water and clean them a little with emery cloth. The cathode plates must have holes to which the terminals for connecting the conductors are attached. A simple and reliable way is to clamp the wire using a screw with a nut and washers. Ensure reliable contact! A weak contact causes heating, sparking, and the electrode can turn off without you noticing! And then you will wonder why one side of the part was etched well, and the other very poorly.

Conductors.

There are two requirements: they must withstand current up to 10 amperes without heating and have waterproof insulation.

OSG 06-05-2008 23:18

So we need details! How, what, in what...

Konstantinich 06-05-2008 23:22

Alhim 06-05-2008 23:37

So, can this be done on desktop boxes?

mexanicus 06-05-2008 23:39

Well, not for himself!!!
Technology in the studio. And even better is a worklog.

Vorkuta 06-05-2008 23:45

quote: Originally posted by Konstantinych:

So, can this be done on desktop boxes?

I think it’s possible on anything that is metal.

I did it simply as described on the “help for beginning knife makers” thread.
1. I took a liter jar, poured three heaped tablespoons of salt (you can’t spoil the porridge with oil), and poured hot water from the kettle.
2. Take a regular battery charger, “+” terminal on the blade and “-” on another piece of metal (I took a piece of brass 140X30X1 mm)
3. I set the charger to 6V, the distance between the materials is 4-6 cm, as you like.

But the main thing is not to forget the ink on the blade: what you paint over will remain a drawing!!!

I read a lot about what to paint over, spat, took Tikkurilovsky varnish (urethane-alkyd varnish for wood) and found it in the pantry. And with a brush I applied a design for testing. The jar says it takes 1 day to dry, but I waited 40 minutes (I couldn’t stand it), so I put it in the jar, connected everything, and after 5-10 minutes the result was obvious.

dblsav 06-05-2008 23:50

The pampering was a success, congratulations.
Can't stop now.

Forex 06-05-2008 23:52

Wonderful result!!!
The technology has been mastered...

Kuzya 06-05-2008 23:53

"Congratulations to you, Gleb Georgievich" (C)

In general, a start has been made

Vorkuta 06-05-2008 23:57

quote: Originally posted by Alhim:

Then it will be quite difficult to remove the varnish from all the holes IMHO, but so... why not?

There were no problems with this, I took regular vaporizer and wiped everything off with a cloth, normal. it really stinks of infection.

occasion 07-05-2008 01:26

It turned out fine. I like it....

Nasgul 07-05-2008 06:41

Less stress means better results. To etch small surfaces, you can wrap a piece of cotton wool around the negative electrode, soak it in the same saline solution, and simply wipe the etched area. Pros: it’s fast and you don’t have to bother with banks; it’s easier to control the result. This is how I etch marks on blades using a quick cutter

Vorkuta 07-05-2008 09:13

You can wrap cotton wool around the negative electrode, soak it in the same saline solution and simply wipe the etched area

I tried it, but I didn’t like it. Maybe, of course, I didn’t do it right, well, it took me a long time to wipe it for sure. It was not etched deeply, and then I tried it with a jar

Vorkuta 07-05-2008 09:14

quote: Originally posted by occasion:

Lenin dabbled in boiling water, and Vorkuta dabbled in electricity....

At the age of 5, I put tweezers into a socket and it sparkled like a charm. Since then I have not been friends with electricity.

Serjant 07-05-2008 09:23

I took it to the archives.

Vorkuta 07-05-2008 11:11

Thank you for your attention

Chroniculus 07-05-2008 12:17

inmemories

Nick_Ross 07-05-2008 14:51

In 2004, using a similar technology, I etched inscriptions and logos on anniversary daggers for the 10th anniversary of the office.
I didn’t take any special photos of the etching, but you can see it here.
The drawing was made using photography. Same as for printed circuit boards.
Too small details on the logo...

Truddum 07-05-2008 18:34

quote: Originally posted by Nick_Ross:

The drawing was applied by photo method

What is the technology for transferring images, if not a secret?

Nick_Ross 07-05-2008 19:23

I took a can of positive photoresist from a friend (he bought it for circuit boards at the radio market). Sprayed it onto a degreased surface and let it dry in the dark.
I printed the picture onto plain paper and soaked it in paraffin for transparency (this transparency is already enough). Then the picture is placed on a photoresist (press tightly) and exposed to ultraviolet light (I used a currency detector).
It would have been better, of course, on transparent film, but I didn’t have it on hand.
I had to make do with improvised materials...

Unexposed photoresist is washed off with an alkali solution. And then - into the electrolyte.
You just need to select the current so that it etches evenly. And, of course, place the cathode as parallel to the surface of the future picture as possible.
material in the photo - 4X13

serg-pl 07-05-2008 20:00

quote: Originally posted by Nasgul:
Less stress means better results. To etch small surfaces, you can wrap a piece of cotton wool around the negative electrode, soak it in the same saline solution, and simply wipe the etched area. Pros: it’s fast and you don’t have to bother with banks; it’s easier to control the result. This is how I etch marks on blades using a quick cutter

my father always did this and I sometimes, it’s really easier but there is a minus. when you paint a small pattern, the temperature rises in the process and the pattern may float or the varnish may even come off (then the work is all a waste, try sanding it) but this, of course, depends on the varnish. We use our own homemade varnish (resin + rosin), I can’t tell you exactly the proportions, but you can estimate it yourself from the properties of these substances. the blade is heated and coated with this varnish (the varnish in a solid state in the form of a rod melts on a moderately heated blade) then it is advisable to cover the blade on top of the varnish with soot (for example, from a candle or burning petroleum products) so that the wettability of the varnish is poor. Well, of course, the drawing must be scratched with a needle the first time, if it’s ruined, you won’t be able to stick it on (it will probably stick over in the process). They say you can also print a pattern on glossy paper using a laser in the most wasteful version, then glue it to the blade with an iron, soak the paper and remove it. I’ve never done this myself, but I’ve seen other people’s robots, quite neat.

Nick_Ross 07-05-2008 20:17

quote: they say you can also print a pattern on glossy paper using a laser in the most wasteful version, then glue it to the blade with an iron, soak the paper and remove it. I’ve never done this myself, but I’ve seen other people’s robots, quite neat.

I tried this until I learned about photoresist from a friend
But I liked the other method better.
Food-grade aluminum foil is glued onto a sheet of paper (the glue should not float like a fox from the heat.) It is best to wrap the edges of the foil over the front and back edges of the paper.
Then you print and transfer with an iron.
and then just remove the foil.
Toner adheres to steel much better than to aluminum. Probably due to the oxide film

serg-pl 07-05-2008 20:25

Is it normal for small parts to come off the foil?

Nick_Ross 07-05-2008 20:29

Millimeter wide lines are normal.
but less depends on your luck.
That's why I did it using photographs.
I warn you right away.
I played with an aluminum base on pictures 2x2cm and smaller.
I don’t know how it will behave over large areas...

Alhim 07-05-2008 23:11

Below is the voltage breakdown at the outputs of standard connectors:

That's all...

Boule 27-08-2009 22:22

quote: Well, in general it’s even simpler: any yellow is +12V, blue is -12V
That's all...

hmm... blue, why touch it? take a lot - black

Volcosob 27-08-2009 22:39

I found a rectifier, took it from the printer, but the bullshit there are three wires at the output and which of them is which?

Kneht33 27-08-2009 22:51

are there red and black? - they are needed, if not, the LED is in your hands!

Volcosob 27-08-2009 23:03

termist 27-08-2009 23:10

There is no black and red - everything is yellow, but I’ll try with a diode.

try it with a tester

Volcosob 28-08-2009 12:44

You can try, but I only have an indicator screwdriver.

termist 28-08-2009 11:51

quote: Originally posted by Volcosob:

, but I only have an indicator screwdriver.

how many volts does it run on?

Volcosob 28-08-2009 14:17

The thing is that from 220.

termist 28-08-2009 15:43

quote: Originally posted by Volcosob:

The thing is that from 220.

then ask your friends for a tester

car-bon 28-12-2009 05:34

On a quick cutter, the pattern turns out black due to the fact that the carbon that is present in the steel remains, but in stainless steel it is absent or small. This carbon can be easily removed with a wire brush on a drill, and then with a polishing attachment. It also gradually wears off naturally, which is why I rip it off right away so that it doesn’t come off in spots later.

Balamutishche 03-01-2010 12:00

and if you poison on Damascus what will happen????????????? who will answer

termist 29-10-2010 22:42

yes, and don’t forget to put the green one on ground to turn it on

hmm which one exactly, I’m sitting with the block in my hands, I don’t know what to do, how to launch it ((((((

termist 29-10-2010 23:51

I’m answering my own question. if you run the block according to advice

quote: Originally posted by Buhl:

Boule

failed, load with 12 volts or 5 volts, or light bulbs from a car, or a cooler (as I did)

Emi1 23-03-2011 06:56

Question about the charger from the printer, there are 3 wires coming from the converter, which ones do we need? The extreme ones?

Drogmoth 23-03-2011 08:00

I did it a little differently. Instead of a jar of electrolyte, a gauze swab was attached to one of the wires, which was periodically moistened in the solution. and led them along the iron.

termist 23-03-2011 09:40

quote: Originally posted by Emi1:

There are 3 wires coming from the converter

black and red are there, they are yours

SH-Andrey 23-03-2011 09:52

4. I used a charger for car batteries as a DC source (produces 12 volts, there are 2 modes: 4 and 6 amperes. I worked at 4 amperes);

5. I used a piece of aluminum as an electrode;
6. Well, then everything is according to the scheme: minus to the electrode, plus to the workpiece (IMPORTANT!!! The electrode and the workpiece must not touch. Maybe this goes without saying for everyone, that’s why they don’t write about this in any instructions on Hansa, but I I didn’t even think about this. I’m an absolute nerd when it comes to electricity and in general I’m terribly afraid of it. Thanks to the kind people for the advice);
7. When everything was finally ready, I turned on the device. The electrolyte immediately began to bubble and some kind of dregs began to stand out. As I understand it, these were particles of varnish. It's a terrible sight, I'll tell you;

8. After 2 minutes I pulled it out, rubbed it with sandpaper and... Oh, miracle! Happened!

9. Inspired by success, I decided to try etching in reverse, that is, etching not the drawing, but the background. The technology is the same. I painted a rectangle with varnish, with the letter “S” in it. The same two minutes of boiling. It worked again.

I came to a conclusion for myself: the most difficult thing in all this is to create a clear drawing. You need to either make a stencil or ask some artist you know (preferably a tattoo artist) to scratch out what you want with a steady hand. Another thought arose: there is such a service as engraving. In our city, I know a couple of places where they do engravings, I even ordered inscriptions on gifts from them a couple of times.
You can ask the engraver to make the desired design on the blade, then cover it with colorless varnish and scratch all the engraving lines with a needle. What will come of this is interesting, considering that engraving already leaves grooves in the metal, albeit not so deep.

three times on 09-04-2012 09:22

quote: Originally posted by sansem80:

I concluded for myself: the most difficult thing in all this is to create a clear drawing

“Ot immanno, oot immanno!” (c) Khryn Morzhov.
A quality drawing is the cornerstone of etching and scrimshaw.

rudy3 28-06-2012 10:23

quote: Originally posted by Ivaldan:
The first experiment in electrochemistry turned out to be shit, but I still want to “brag”

The blade was painted over with spray paint, then the ricun was scratched. Photo after a little cleaning, it was completely scary. There are pores in the paint, the entire blade has spots, especially on the butt. The paint has peeled off in some places. In addition, there was a problem with currents, I had to turn it off after 3 minutes.
It’s not for nothing that I’m afraid of electricity.

rikitikitavi666 29-06-2012 22:13

prim2005 29-11-2013 15:55

quote: The only thing is that it is not clear how a blade with a mixture from “Mole” will behave.

Actually, “Mole” is needed to remove photoresist; it can be removed simply with acetone or solvent

Ulman@Serjan 30-11-2013 13:45

Alyoshenka1986 13-08-2014 20:18

quote: Originally posted by Ulman@Serjan:

Or maybe someone can tell me how to do etching so that it looks like this kind of coating?

I’ll join, I’m very interested too)

Metal engraving! Basic principles.

The basis of the technique is the method of electrochemical etching of metals. Briefly, it is as follows: The part on which the inscription or drawing is made (previously applied with a special varnish) is immersed in an electrolyte solution; it is the anode. That is, the (+) current source is connected to it. The cathode, which is also immersed in the electrolyte solution, is a strip of stainless steel. The (-) current source is connected to it. When the current is turned on, electrochemical etching occurs, that is, the dissolution of the surfaces of the part unprotected by varnish.

The figure schematically shows the principle of the process.

The numbers show:
1. Metal part.
2. Etched area.
3. A layer of varnish keeps the metal unetched.

This is the basis. Now let's look at the whole process in detail.

1. Preparation of the part.

As a rule, it comes down to thoroughly degreasing the surfaces on which the varnish will be applied. Why is this being done? Firstly, the varnish sticks very firmly to the degreased surface, which guarantees that during the etching process it will not be torn off by parts, which will lead to irreparable defects in the form of undesirably etched areas. This can completely ruin the product.

Secondly: if there is a non-greasy area left on the surface to be etched. For example, even your own fingerprint! This fat can act as a layer of varnish, protecting the surface from etching. And then you get an etched fingerprint. This defect is unpleasant, but in most cases it can be eliminated by re-grazing.

And so we will clean the surface from foreign dirt, debris, etc. Be sure to wear rubber gloves so as not to leave fingerprints. And it’s easier to work this way in hot water.

Photo: washing the knife under running water and soap.

Degrease by soaking the part in a solution of soap, washing powder in hot water for some time. Then you need to thoroughly clean the part with a toothbrush (a toothbrush will do) in the same solution. Particular attention to blind (not through) holes. They are very difficult to wash. You can't leave dirt there. Washing is carried out under running water as thoroughly as possible. Don't take off your gloves! From now on, it is generally extremely undesirable to touch the part with hands without gloves, in order to avoid the appearance of the defects described above. If you do touch the part, it is better to repeat the degreasing process. How to check the quality of degreasing? Very simple. Water drains completely from well-degreased metal, leaving no drops or streaks. If drops remain, water sticks to the metal (exact expression), then there is fat in these places. Scrub them with a brush and solution more thoroughly and repeat washing and checking.

Another secret. An ultrasonic bath is used to degrease complex parts that have difficult-to-clean holes, crevices, etc. At home, it can be successfully replaced with a household ultrasonic compact machine. The use of ultrasound significantly reduces degreasing time and improves quality. But in most cases this is not necessary.

Small parts can be degreased by wiping with cotton wool and tooth powder moistened with alcohol. The powder contains soda, which will remove fat. A very quick method of degreasing, but it requires some skill.

Photo: degreasing with alcohol and tooth powder.

2. Preparation of a special varnish.

A special varnish is used to apply inscriptions and designs on metal. The composition and method of preparation have been developed as a result of practical work and, when following these recommendations, guarantee the quality of work. The varnish provides reliable protection of parts of the part from etching and is easily removed at the end of the process. We will need the following ingredients to prepare it:

- Gudron. The substance is black, fragile. Widely used in construction for roof waterproofing and road repairs. Sold in building materials stores in large pieces of 50 kg. For our purposes, such an amount will not be needed. Therefore, it’s easier to look for a piece of tar at construction sites, ask workers pouring roofs or repairing roads. In such cases, as a rule, fragments remain and are simply thrown away. It is important to find a sample that is clean and free of sand and other debris. The content of foreign impurities is highly undesirable and will significantly reduce the quality of the finished varnish. Main component. The required quantity is almost equal to the volume of the finished varnish.

- Rosin. A fragile, amber-colored substance. Made from pine resin. Widely used in soldering electrical products. Inexpensive. Sold in hardware stores, can also be sold as part of soldering kits, together with a soldering iron and tin. The required amount of crushed matchboxes (about 30 cc). Approximately.

- Gum turpentine. A flammable liquid used as a solvent for some paints and varnishes. Sold in hardware departments next to paint. Usually in 0.5 liter bottles. One bottle is enough.

As you can see, all three substances are readily available and inexpensive. Also not hazardous to health.

The tar must be crushed (cracked with a hammer) and placed in a metal container with a lid, in which we will prepare the varnish. Add turpentine there and stir to dissolve. You can leave it for a while to dissolve the tar pieces. Rosin is also crushed and mixed with pieces of tar. Although some sources recommend adding rosin to already dissolved tar. The main thing here is to ensure melting and uniform mixing. It is desirable to obtain the viscosity of liquid sour cream. Now you need to heat the mixture for better mixing.

Heating is carried out on an electric stove, at a low heating setting. It is not recommended to use heat on a gas burner due to the risk of fire. I highlight the most important issue of fire safety separately.

Attention! Varnish and its components are flammable!

Do not use open flame sources to heat the varnish and do not cook the varnish near the fire! Fumes from molten tar are also flammable! If a grayish-white smoke, this is a signal of dangerous overheating. Do not open the lid! Vapors can flare up at any second even from simple stirring. Immediately and carefully, without jerking, remove the container with varnish from the heated stove and cool. Do not cook varnish in residential areas; it is better to do this in well-ventilated places, as a characteristic odor appears. Just in case, prepare a piece of thick fabric. If your polish catches fire, don't panic! Don't put it out with water! Cover the container with a tight lid or cover the fire with a thick cloth. The flame will go out immediately without oxygen. When extinguishing with water, you can be scalded by water vapor, burning splashes of varnish will fall on the body, clothes and objects, and then burns and a fire in the room are inevitable! Never move away from cooking varnish.

The main reason for all fires is that they forgot the varnish on the tiles and went out to drink tea!

If you take reasonable precautions, you will avoid fire. There are practically no cases of fires at work these days.

Heating with stirring is carried out to a temperature of 60-70 degrees. This ensures that the components are mixed and a varnish with the required properties is obtained. Now the varnish can be cooled and stored in a container with a tight lid. The varnish will thicken slightly as it cools.

Simplified preparation of varnish.
You need to purchase ready-made bitumen varnish. It is also freely available in paint and solvent departments. It is used in everyday life to protect water pipes from rust. The varnish is diluted with turpentine and finely ground rosin is added. Approximately a matchbox of rosin for 0.5 liters of varnish. Stir thoroughly under low heat until completely dissolved. Don't forget about fire safety! Cool and pour into a container for storage.

Before direct use, the varnish is diluted with turpentine to the required thickness. The varnish does not deteriorate during storage for a long time. If it thickens, you can always dilute it with turpentine.

3. Applying a design to a knife (another part).

You will say that only an experienced artist can draw a picture or an inscription. But what about someone who doesn’t have the ability to be an artist? The situation here is not at all hopeless. Even experienced artists resort to simple tricks that can significantly improve the quality and speed of drawing. Using this technique, almost any person (of course, if your hands don’t shake!) can successfully achieve good quality. A little practical experience will greatly increase your confidence in your work.

First you need to decide on the future miniature or inscription. Make a preliminary pencil drawing on a scale of 1:1 (it's called a sketch). At the same time, no one forbids you to cut out a suitable design from a magazine, newspaper, etc. with scissors. You can also run it on a computer, if you are familiar with the necessary programs, set the required scale and print it.

Photo: Preparing a sketch on the computer.

Now let's apply the design to the degreased surface of the knife, details using transfer paper! You just need to use a color translation of yellow, red, white (there is one). The transfer of black and purple colors does not leave marks on the metal.

Photo: The knife is inscribed with yellow transfer paper.
Horizontal lines are also marked for writing straight letters.

Advice from an experienced master: To prevent the design from shifting during copying, it and the transfer paper are secured with pieces of tape. Then the drawing is translated using a pencil or pen. The line marks from the transfer paper will allow you to continue varnishing easily and accurately.

4. Painting with varnish.

To draw the future drawing and inscription with prepared varnish, you need to use thin brushes or feathers. By choosing the optimal thickness of the varnish and with a little practice, you can quickly learn how to draw the translated drawing. If you have some experience, you can also freely write with a pen, even without first marking with transfer paper.

Photo: the artist traces the translated inscription with varnish using a brush. Please note: a wooden hand rest is used. A stand in the form of a bench 3 cm high above the table surface. (width 6 cm, length 30 cm). Facilitates precision work and relieves stress, allowing you to work for a long time without fatigue. The stand prevents your hand from touching the grease-free metal surface.

The operation requires some skill and patience. Don't be discouraged if it doesn't work out the first time. You can always easily wash off the varnish using the same turpentine, solvent, gasoline (just use pure unleaded gasoline for nefras or galosh lighters, leaded gasoline is poisonous!) and try again.

Photo: Binocular glasses with 5X magnification.

Photo: The pattern on the knife is painted with varnish. Please note: continuous varnishing of areas not subject to etching has not been completed completely. This is done with the expectation of subsequent surface protection using plasticine!

5. Pre-drying the varnish.

The next technological operation is preliminary drying of the varnish to a semi-solid state. To do this, it is enough to leave the part in a ventilated place for 2-3 hours at room temperature. The varnish will partially dry and thicken.

6. Final elaboration of the drawing.

While applying the drawing with a brush or pen, you may have made some inaccuracies, mistakes and painted over those places that should have been left under the grass. Now you can fix all these defects. Using a sharpened stick made of wood, plexiglass, PCB or a thin metal needle, it is necessary to remove the varnish from excessively painted areas. You also need to clean up the edges of curved lines, making them smoother and more attractive. Trimming the edges of the lines is also important in view of the fact that the layer of varnish at the edge of the drawing is always thinner, and there is the possibility of unwanted etching. By removing varnish from the boundaries of lines, we thereby make the boundary layer of varnish thicker and increase its reliability.

Photo: tools for final elaboration of the drawing. A plexiglass stick, a needle at the end of a stick from an old brush, a fountain pen.

During final processing, an engraving operation is also performed. It involves scratching fine lines using a sharp needle attached to the end of a stick from an old brush. This way you can make very thin etched lines or write an inscription or imitate the knife number.

Removal of grains of excess varnish should be done by blowing off or using cotton wool soaked in alcohol. Alcohol does not dissolve varnish and easily removes debris. If you use turpentine, pure gasoline (galoshes) or any other solvent, the drawing will simply be washed off completely. This way you can delete unsuccessful work results, which is very possible at the initial stage.

Photo: The thin lines scratched with a needle are very clearly visible.
For this operation, it is advisable to use a magnifying glass or binocular glasses.

7. Drying the varnish.

You can finally dry the varnish in various ways. Drying is a very important and responsible operation, the quality of which determines the result of the work.

The most common and reliable way- This is oven drying. Temperature 100-130 degrees. Drying time - 30-40 minutes. Then cool at room temperature. However, this method is used for large volumes of work. At home, we can recommend drying it in an old electric oven set to the lowest heat setting. Do not use ovens that are used for cooking! The remaining smell will linger for a long time and will make cooking impossible! If you forgetfully exceed the drying time, there may be cases of overdrying of the varnish.

Another way- this is natural drying. Just leave the part at room temperature in a ventilated place. Usually the varnish dries completely in 3-4 days. Drying is quite high quality, but very long. To speed up the process, tabletop heat fans are used, with the help of which drying occurs in 1-2 hours.

Photo: Drying varnish using a fan heater.
1 - fan heater.
2 - Details.

Then the cold air flow mode is turned on and the part quickly cools down to room temperature. Perhaps this is the only drying method for parts that have elements that are afraid of heating. For example, writing on a knife that already has a handle assembled. You can’t heat such a knife in a drying cabinet; you can simply burn the handle!

A special warning applies to knives in which the handle is attached to the blade using epoxy resin. When heated to 80-90 degrees, the resin softens and collapses. When it cools, it will not harden again. You can work with such a knife only after disassembling it. How to remove the handle? It’s very simple: heat the blade to 80-90 degrees and pull out the handle!

With natural drying there is practically no danger of over-drying the varnish.

A high-speed drying method is possible using an electric stove. The part is held with the help of a heat-insulating device (you can use pliers) above the heated surface of the electric stove 5-10 cm. The method is quite dangerous due to overheating of the varnish and its fire. The end of heating is considered to be the moment the temperature reaches 100-130 degrees. At this temperature, a drop of water falling on a heated part hisses and rolls along the surface. Which can serve as a simple heating indicator. This is then followed by cooling to room temperature. If you overheat a part, you can very easily dry out the varnish.

A well-dried varnish becomes rigid and does not leave a dent when pressed with the tip of the nail.

8. Danger of overdrying the varnish.

If it overheats or takes too long to dry, the varnish becomes too strong to such an extent that it becomes impossible to remove it with gasoline or any other solvent! This varnish turns into a durable coating, which can only be removed mechanically: by sanding with sandpaper or even using sandpaper!

This can very easily damage a part or a knife. Don't forget about the part located in the drying cabinet or above the tile! Better set a timer for reminders!

Forgetfulness is the main cause of dryness and fires!

Don't forget about fire safety rules! All the above precautions remain relevant during this operation!

Carefully inspect the quality of the dried varnish. It is very possible for bubbles to appear due to very rapid heating. They need to be tinted and dried for a short time.

Photo: part after etching; bubbles that arose during drying led to the appearance of undesirable etched spots (highlighted in red). The defect is irreparable.

9. Operation after drying.

Before subsequent weeding, it is necessary to additionally rinse and degrease the part, which is done by lightly wiping with cotton wool moistened with alcohol and a small amount of regular tooth powder. Then finally with pure alcohol. We have already discussed the need for this in the chapter devoted to surface degreasing. You will also additionally check the strength of the dried varnish.

10. Preparing the part for etching.

It is not at all necessary to paint over all other surfaces with the same varnish. It is enough to limit yourself only to the area around the inscription or drawing. For protection, you can successfully use plasticine, polyethylene and other available materials. Plastic lids and packaging for mayonnaise and other products can be very useful, from which it is convenient to cut out the necessary templates. Carefully wrap the knife handle with plastic wrap, securing it with electrical tape and tape. Plasticine, ordinary, for children, will reliably protect metal surfaces from etching. In general, it is necessary to try, if possible, to protect large painted surfaces with an additional layer of plasticine, which will provide additional protection against unwanted mordants. Looking ahead a little, we note that you immediately need to take care of securing the electrode, and the place of fastening also needs to be protected. At this stage there cannot be any specific recommendations; it all depends on your capabilities and the properties of a particular part. The main requirement is to provide hermetically sealed protection for parts not subject to etching.

Photo: the knife is prepared for etching the inscription. The handle is protected by a layer of polyethylene and tape. The blade is protected with plasticine. Only the etched inscription is left open.

Photo: the part is prepared for etching. Protection with plasticine. The wire for connecting the current is clearly visible.

11. Installation for etching.

The general design of the installation can be seen in detail in the diagram. It consists of a direct current source, a vessel (bath) for etching with electrolyte, stainless steel electrodes (cathodes), the part to be etched and conductors connecting the current source to the electrodes.

Let us explain in more detail.

DC source.

In general, the source must provide a constant current of 3-10 amperes; an ammeter that constantly shows the current is required. It is desirable to have protection against short circuits due to negligence, which can be successfully provided by a fuse of the appropriate rating. In practice, there is no need to purchase an expensive current source with a digital display and a built-in timer. An excellent solution is a device for charging car batteries. It is very possible that you have had it in your garage for a long time. And it's inexpensive to buy. Typically, such devices are equipped with an ammeter, a fuse and a current switch. For craftsmen familiar with electrical circuits, we can recommend assembling a homemade rectifier. I note that smoothing capacitors at the output of the current source are not at all necessary; rectified current with ripple is quite suitable. For pulsed current sources, a capacitor is still needed.

Pickling bath.

It is desirable that the bath be made of non-conducting material. For example: polyethylene, plastics, etc. The main requirement: the part must fit freely in the bath completely immersed in the electrolyte. It is possible to carry out the weeding in a metal container, but it is necessary to isolate both the electrodes (cathodes) and the part from electrical contact with each other. Remember that this significantly increases the risk of electric shock! Do not touch the metal bath while the current is on! Such a bath must be grounded. The safest way is still to use non-metallic utensils. Get creative. For example, to weed long blades of swords, sabers, checkers, use a piece of polyethylene pipe with a diameter of 150-200 mm and the required length as a bath. The bottom of the pipe is, of course, capped. Often, for weeding a single copy of a knife, it is quite possible to use a 1.5 or 2 liter plastic bottle of mineral water or beer, having previously cut off the top part. Although the electrolyte is quite harmless, it is still not recommended to use food utensils for pickling.

Electrolyte composition.

A simple solution of table salt is suitable for weeding most modern stainless steels! For a liter of plain (not distillate) hot water, add 3-5 tablespoons of salt and mix thoroughly. Sometimes it is recommended to add 8-10 milliliters of hydrochloric acid (concentrated) to such an electrolyte. Use extreme caution when handling acid! Although in practice, weed works just fine without it.

To pickle rusting types of steel, copper, brass, aluminum, add a tablespoon of copper sulfate to the salt solution. It is sold in hardware departments, fertilizers (bluish-green powder). I note that aluminum will be etched without any current being connected at all, releasing a large amount of heat. The electrolyte may boil.

The electrolyte is relatively harmless to health, you can work without gloves, but there will be stains that are difficult to wash off. After work, you still need to wash your hands with soap and warm water. It is quite possible to flush the used electrolyte into the city sewer, along with a large amount of water. The electrolyte has a limited service life. That is, during the etching process it is saturated with metal salts and gradually loses its properties. Insoluble brown and green precipitates also accumulate and contaminate the drawing and interfere with observing the process. This electrolyte needs to be replaced. Or let it sit and carefully pour, discarding the sediment.

Previously, solutions of strong acids were used for etching without the use of electric current. We don't recommend doing this. This is a rather dangerous and unhealthy process that requires exhaust ventilation; it is necessary to work with glasses and protective equipment. In addition, modern steels are so resistant to acids that it will take a lot of time with no guarantee of results.

And our simple, safe electrolyte copes with any steel!

Electrodes (cathodes, -).

The most suitable material for manufacturing is mild stainless steel. It is used to make dishes, thermoses, water tanks, spoons, and forks. Most often, the electrodes are strips of sheet steel located on both sides along the walls of the etching bath. If the part has an etched pattern on one side, it is necessary to place the electrode opposite the etched surface, otherwise etching with different (uneven) depths is possible, which is a noticeable defect. Accordingly, if we etch two opposite sides of a part (knife) at once, the electrodes should be on two opposite sides. The size of the electrodes (their surface area) is not particularly critical. The main thing is that the electrode must exceed the area being etched, otherwise an uneven etching depth may be obtained. To etch a small inscription on a knife, the author successfully used an old stainless steel tablespoon. (True, then it took a long time to clean it with sandpaper!) The service life of the cathodes is not limited. They do not dissolve during operation, but only become dirty. Metal salts are deposited on them; when brass is etched, a layer of copper is deposited on them.

Photo: brass etching. A layer of copper appeared on the electrode after 15 minutes from the start of the process, which can be easily removed by washing in hot water. After which the etching continued.

Caring for them consists of rinsing with hot water and sanding a little with emery cloth. The cathode plates must have holes to which the terminals for connecting the conductors are attached. A simple and reliable way is to clamp the wire using a screw with a nut and washers. Ensure reliable contact! A weak contact causes heating, sparking, and the electrode can turn off without you noticing! And then you will wonder why one side of the part was etched well, and the other very poorly.

Conductors.

There are two requirements: they must withstand current up to 10 amperes without heating and have waterproof insulation.

Pickling room
(Click on the picture to enlarge it)

Hidden camera photo: pickling room at the enterprise.
1 - Current sources.
2 - Bath for pickling stainless steels.
3 - Plasticine.
4 - Bath for pickling brass - small. Made from a 50 liter polyethylene tank. Covered with polyethylene.
5 - Bath for pickling brass - large.
6 - Exhaust ventilation. Used for acid etching. Currently not working.

12. Etching process.

We assemble the installation according to the diagram. We pay special attention to correct polarity. We firmly fix the part and electrodes in the bath. Let's check if there is a short circuit between them. The current strength for etching a pattern on one medium-sized knife is about 3 amperes. It is necessary to set the battery charging device to the minimum current value. Increasing the current will lead to faster etching, but is still not recommended due to the possible phenomenon of varnish stripping. Monitor the process constantly. The appearance of pieces of varnish on the surface of the electrolyte indicates a possible partial separation of the varnish. It is necessary to stop the process, remove the part, carefully rinse it under a layer of water and carefully inspect it. Places where the varnish has been torn off must be repainted and dried again. Then continue the process. If you are etching a large drawing or inscription, you will need to increase the current accordingly. The etching time required is 30-60 minutes. On average, in 45 minutes you can achieve a sufficient etching depth. Check the depth visually, removing the part from time to time. To apply a knife number or a thin inscription, a small depth and time of 15-20 minutes are enough. Over time, you will gain experience and be able to accurately determine when to complete the etching.

Photo: etching in a glass jar.
The electrode and the part are secured using clothespins. The electrode is located only on one side, which is not entirely correct. However, the process was surprisingly successful.

13. Washing.

Disconnect the etched part from the electrodes (after turning off the current!), remove the plasticine and other protective equipment. The varnish is washed off with a cloth soaked in turpentine. The final, final rinsing is done with galosh gasoline (for lighters).

The resulting drawing and inscription have a gray-matte background. It should be noted that in the background of the picture there are metal salts and other indelible substances and etching products. They are not harmful to health and this knife can be used to cut food. For most purposes the job can be considered complete.

Photo: Finished drawing on the knife. Etching time 30 minutes. Current strength is 2.5 Amperes. There are no defects.

Photo: Brass part. Etching is complete.

Photo: Same detail. The plasticine was removed, the varnish was washed off with turpentine. The etching depth is clearly visible. Etching time 45 min. Current strength is 1.2 Amperes. The process was successfully completed in a glass jar!

14. Additional operation for processing the background surface of the picture.

With a little work, you can give the background of the picture a metallic shine by clearing it of weed products.

Photo: The polished design has a shiny background and looks more attractive.

This is done by polishing the design, and the rest of the knife does not interfere with bringing it to good condition. Why do we need the following materials:

1. Electric emery or electric drill with a device for attaching to the table.
2. Nap circle with synthetic bristles.
3. Diamond polishing paste. The grain size is 10-40 microns or 7-10 microns. The colors of the pastes correspond to grey, blue and green. Diamond pastes have colors that correspond to the grain size. You can use pastes with a fine grain of 2-3 microns (yellow color), it will give a very good shine, but you will have to work longer.

Photo: Polishing the pattern with diamond paste with a grain size of 7-10 microns (green). Homemade emery is made on the basis of a washing machine motor.

As you probably already guessed, you need to fix the circle on sandpaper or a drill and carefully polish the design using diamond paste. The operation is so simple that it does not require a detailed description. We just need to remind you that you need to wear protective glasses and gloves when working. Hold the knife tightly! There is a great danger of cutting yourself, especially if it is well sharpened! From time to time, wipe the surface with a cloth soaked in gasoline. Quite quickly the background, as well as other surfaces, will acquire a metallic sheen.

Photo: giving final shine using diamond paste with a grain size of 2-3 microns (corresponding to yellow color). Please note: a soft fabric circle is used.

In conclusion, it can be noted that small inscriptions can be polished without using sandpaper, etc. An old toothbrush will successfully replace a polishing wheel. However, such cleaning will require much more time.

Photo: polishing a design with an old toothbrush.

15. Conclusion.

In this guide, we examined only the most important, key points of the method. In each specific case there may be deviations depending on the tasks and your capabilities. Don't be afraid to improvise and experiment! (Of course not on the customer’s things). It's safe to say that a little practice will give you confidence and allow you to achieve excellent results.

Photo: Examples of successfully completed work.

Every buyer of this technology has the right to ask questions that may have arisen while reading the material to the author of the book.

You can also count on my tips in the practical application of this technique.
Questions, suggestions and complaints should be sent to mail to [email protected].
I will try to answer as quickly as possible.