Metal etching sometimes replaces casting and engraving; it makes the whole process substantially simpler. You can get a pattern as concave - embossed, and convex - bas-relief. Etching metal at home can be chemical and galvanic. The first option is more toxic when used at home, so for starters we will use the second, it is also called electrochemical.
Equipment
You need to take a power supply or transformer, which can output from 4 to 7 V. In addition, you need a dielectric bath, it must contain the necessary part and a second metal object, which is connected to the anode.
To etch a pattern on metal, it is necessary to use a solution of iron sulfate as an electrolyte . If the pattern is needed on a copper or brass surface, then copper sulfate is used. You can also use ferric chloride. The main thing is that the water be distilled.
Preparing a part for etching
In order for the etching to be uniform and in the right places, the part must be cleaned of dirt and also degreased. For more convenient work, a copper wire is soldered to the part with tin, it will be convenient to hold an object for it. To clean the surface, you need to lower the converted object in 10% sodium hydroxide, the temperature of which is 50 ° C, then in a 15% sulfuric acid solution and hold it there for two minutes, then rinse with hot water. When the procedure is completed, the surfaces of the object will become completely cleaned, and of course, you can not touch them with your hands.
Electrochemical metal etching
We need to protect places that should not be pickled. To do this, apply special mastic to these surface areas. It is made of three parts of wax and two - rosins, they are melted in a tin can, stirring. After everything turns into a homogeneous mass, it is allowed to cool and divided into fragments. Each of them is placed in gauze so that later, when pressed, as much mastic as possible can leak through it. After that, the workpiece, which we will etch, is heated. Now we take the created mixture, which was placed in cheesecloth, and we rub the surface with an even layer.
After cooling, the mastic becomes hard. From above it is covered with light water-soluble paint. It can be watercolor or gouache white. After which the coating should dry. Then you can apply the drawing, it will hold well on the paint. It can be depicted with a pencil or transferred through a carbon copy. Then this contour must be scratched with a needle to the metal itself.
Now the metal is etched by electrolysis, we connect one rod to the anode - plus, the other to the cathode - minus. To the first we connect the part on which the image will be applied, to the second any steel plate. After this, the process of etching the metal begins where the image was scratched.
If you need to create a multi-level drawing, everything is done in the same way as described above. Only the contours are checked each time, and when the smallest of them are etched to the required depth, the part is removed and painted over with heated mastic using a brush. When it hardens, everything is repeated again until the next level of the picture. In the process, an image is gradually created.
In this way, the metal is etched at home, after which the surface is washed with turpentine, and then polished, giving the product a complete look.
Chemical etching
Now consider how to create a pattern on a metal surface without the use of electrical appliances. To do this, we need chemicals that are freely sold in hardware stores. So, let's begin. For etching we need:
- "White Spirit";
- paint that does not dissolve in White Spirit;
- acetone;
- resin, which is used to cover roofs;
- common salt;
- copper sulfate.
Part cleaning
To begin with, the part where the image is planned is cleaned with fine emery paper and degreased. When the surface is ready, you need a place where the drawing will be applied, stick it with duct tape or something like that. After that, the rest of the surface where chemical etching should not affect the metal is painted over. It can be of any color, the main thing is to be resistant to the White Spirit.
When the paint dries, you can remove the adhesive tape. Beneath it is pure metal, ready to create a picture on it. Now on this "mini-canvas" you need to apply the image. It is made using resin, which is dissolved in White Spirit, until it becomes liquid, like paint. She draws the desired image with a brush. What makes such an impromptu paint good is that if something doesn’t work out in the drawing, you can remove it by dampening a cloth or cotton swab in White Spirit. If the picture has very small details that did not work well with a brush, they can be corrected with a needle, scraping off excess after drying.
In this way, you can etch a knife, keys, in general, any metal object. Now that the drawing is completely ready, you can proceed to the etching itself.
Pickling solution
We need a liter of water, in which we need to dissolve 100 g of copper sulfate, and then add salt. It needs to be strewed until it stops dissolving. The resulting mixture will have a blue color. However, after a metal object is immersed in it, the color will begin to change to green.
So, immerse the part. The chemical process begins immediately. In all this production no harmful substances are emitted, therefore such etching of metal at home is safe.
Chemical reaction
During the reaction, a plaque forms, which will become more and more. It slows down the whole process, so you need to periodically wash it off with water. You should not do this with various brushes, brushes and other tools, because you can damage the paint. But she seemed to hold the whole drawing, and it would be a shame if, by etching a knife, for example, you accidentally damage the drawing on it. This is a very delicate job requiring a steady hand and patience.
The depth of the pattern directly depends on the time during which the metal will remain in solution. There are no exact criteria, therefore, each master must himself observe the progress of the chemical reaction. And only after doing this several times, it will be possible to say with confidence what time is needed for the manifestation of the desired picture to the intended depth.
Advantages and disadvantages of electrochemical and chemical etching
The advantages of electrochemical metal etching at home include the fact that the created pattern is clearer, it can be clearly seen if you look at it with magnification. However, the minus is that this method requires an electric device, which not everyone can have.
The advantages of chemical etching include the fact that everything you need can be bought at a hardware store. These ingredients are cheap, and, most importantly, you do not need to look somewhere for a power supply or other devices that can deliver from 4 to 7 V. However, the imperfect edges of the picture are a minus.