Progressive corrosion of materials leads to their deterioration, which poses a major safety risk. Moreover, damaged infrastructure can also result in significant financial losses. Corrosion is caused both by unfavourable environmental conditions, such as high levels of humidity or salinity, and by dirt on the steel. In order to clean the steel surface of grease or after welding, and also wherever the chromium content of the surface has been reduced, it is advisable to etch the material.
Etching of steel is a process during which all discoloration, impurities and also oxides are removed from the surface. Before etching of steel, it must be cleaned by using degreasing agents. Typically, etching is carried out by using a mixture of acids such as nitric acid, hydrofluoric acid and sometimes sulphuric acid. The acids are mixed in the correct proportions. The addition of reagents that contain chlorides, such as hydrochloric acid, should be avoided, as this could contribute to pitting corrosion.