Chemical etching of a metal means the removal of flux or oxide residues from its surface. Such a process involves the use of a solution of chloride salts, alkali or an acid solution. Regardless of which aggressive chemicals are used, metal etching requires extreme caution and accuracy from a person, since such substances are quite dangerous and can cause chemical burns if they come into contact with the skin . Nevertheless, with proper preparation, this process can well be carried out at home. Etching of metals allows you to reproduce any plot, text, in-depth or embossed ornament on almost any metal surface. The products that result from it are really worth it to devote some free time to studying this technology.
The essence of the process
Etching of metals can be either complete, which is usually used for simple cleaning, or partial, which is often used to decorate objects. In the latter case, the so-called resist is used to protect areas that should not be subjected to such processing. Etching of metals can be carried out either by chemical or galvanic methods. In the first case, the product is immersed in the solution. Processing time depends on the required etching depth and the type of material itself. After extraction, the metal is thoroughly washed with cold water, to which an aqueous solution of soda is sometimes added. Thanks to this, you can be sure that traces of acid will not spoil the result.
Metal Art Etching
It was used in the Middle Ages to decorate weapons and armor. By their beauty, such products are often not inferior to the creations of the hands of skilled jewelers. For this type of metal surface treatment, the second, that is, the galvanic method, is best suited. This method avoids the emission of gases harmful to humans that occur during chemical treatment, and is much more effective, since it makes it possible to make the edges of the etched pattern more clear.
Galvanic etching in practice
In order to show your talent and begin this process at home, the first thing you need to find a direct current source, whose voltage is approximately equal to 4-7 volts. The ideal option is a household power supply with a switch. Then you need to get a bath of insulating material, which will contain electrolyte. As the latter, a saturated solution of ordinary salt can be used, but sulfate solution is usually used for this purpose . Iron is used for iron and steel, and copper - for bronze, brass and copper.
The metal workpiece must be degreased in advance. To do this, a
copper wire is soldered to it
, holding on to which they lower it for 5 minutes in a solution of sodium hydroxide, heated to a temperature of 50 ° C. Then the workpiece is transferred for several minutes into a liquid with a 15% sulfuric acid content, after which it is thoroughly washed with hot water. The last preparatory stage is the preparation of mastic. In a tin box, mix var, rosin and wax in a 4: 2: 3 ratio and melt until a homogeneous mass is obtained. When it cools down, wrap it in a strong thin cloth and drive along a slightly warmed blank until it is covered with an even thin layer. After all this has hardened, apply the desired drawing
with watercolor paint and scrape off the mastic with a knife where the recesses should turn out. Now place it in the electrolyte by connecting a terminal with a positive pole to it, and suspend any metal object to the wire with a minus sign and also lower it into the electrolyte. Upon completion of etching, unsolder the wire, rinse the resulting masterpiece with turpentine and perform the final finish (grinding and polishing).