Etching of metals: theory and practice

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Chemical etching of metal means the removal of flux or oxide residues from its surface. Such a process involves the use of a solution of chloride s alts, alkali or acid solution. Regardless of what 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. However, with proper preparation, this process can be carried out at home. Metal etching allows you to reproduce any plot, text, in-depth or relief ornament on almost any metal surface. The resulting products are truly worth spending some time learning about 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 lastIn this case, to protect areas that should not be subjected to such treatment, a so-called resist is used. Pickling of metals can be done either chemically or galvanically. In the first case, the product is immersed in a solution. The processing time depends on the required etch 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.

Artistic metal etching

It was used in the Middle Ages to decorate weapons and armor. In terms of their beauty, such products were often not inferior to the creations of the hands of skilled jewelers. For this type of metal surface treatment, the second method, that is, the galvanic method, is best suited. This method avoids the release of gases that are harmful to humans, which occur during chemical processing, and is much more effective, since it makes it possible to make the edges of the etched pattern more distinct.

Etching in practice

In order to show your talent and start this process at home, the first thing you need to do is find a DC source, the voltage of which 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 the electrolyte. As the latter, a saturated solution of ordinary s alt can be used, but usually for thistargets use a solution of vitriol. Iron is used for iron and steel, and copper is used for bronze, brass and copper.

Metal billet must be degreased in advance. To do this, solder a copper wire to it, holding on to which it is lowered for 5 minutes into a solution of caustic sodium, 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 ratio of 4:2:3 and melt until a homogeneous mass is obtained. When it has cooled, wrap it in a strong, thin cloth and run over the slightly heated workpiece until it is covered with a uniform thin layer. After all this has hardened, apply the desired pattern with watercolor paint and scrape out the mastic with a knife where the indentations should be. Now place it in the electrolyte by connecting a terminal with a positive pole to it, and hang any metal object from the wire with a minus sign and also lower it into the electrolyte. Upon completion of the pickling, desolder the wire, rinse the resulting masterpiece with turpentine and perform the final finishing (grinding and polishing).