Etching metals: theory and practice

Chemical etching of the metal means the removal of residues of fluxes or oxides from its surface. This process involves the use of a solution of chloride salts, alkali or an acid solution. Regardless of which aggressive chemical reagents are used, pickling of metals requires extreme caution and accuracy from the person, since such substances are quite dangerous and, if ingested, can cause chemical burns. Nevertheless, with proper preparation, this process can be carried out at home. Etching metals allows you to reproduce any subject, text, deepened or relief ornament on almost any metal surface. The products that are obtained as a result are really worthwhile to devote a certain amount of free time to studying this technology.

The essence of the process

The etching of metals can be either complete, which is usually used for simple cleaning, and partial, which is often used to decorate objects. In the latter case, a so-called resist is used to protect areas that should not be subjected to such treatment. The etching of metals can be carried out either by chemical or galvanic means. In the first case, the product is immersed in a solution. The processing time depends on the required etching depth and the type of material itself. After extraction, the metal is thoroughly washed with cold water, into 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 their beauty, such products are often not inferior to the creations of skilled jewelers. For this type of metal surface treatment, the second, i.e. galvanic, method is best suited. This method avoids the release 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 their talent and start this process at home, the first thing to do is to find a DC source whose voltage is approximately 4-7 volts. Ideal option - 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 common salt can be used, but usually a solution of vitriol is used for this purpose . Iron is used for iron and steel, and copper is used for bronze, brass and copper. The metal workpiece must be degreased beforehand. For this, copper wire is soldered to it , holding it for 5 minutes in a solution of caustic sodium, heated to a temperature of 50 ° C. Then the workpiece is transferred for a few minutes into a liquid with 15% sulfuric acid content, and then 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 cools down, wrap it in a sturdy thin fabric and drive over a slightly warmed preform until it is covered with a uniform thin layer. After all this hardens, apply the watercolor paint to the desired pattern and scrape the mastic with the knife where the recesses should be. Now put it in the electrolyte, connecting a positive pole terminal to it, and hang any metal object in the wire with a minus sign and also lower it into the electrolyte. After completing the dressing, solder the wire, rinse the masterpiece with turpentine and perform the final finish (grinding and polishing).