What does the pickling process involve?

The pickling process is primarily focused on the removal of rust, scale, and other impurities from the surface of steel or other metals. This is achieved through the use of acidic solutions, specifically hydrochloric or sulfuric acid. During pickling, the metal is immersed in these acids, which dissolve unwanted materials and leave a clean surface. This process is essential prior to further treatments such as painting or coating, as a clean surface significantly enhances adhesion and overall performance of the coatings applied thereafter.

In contrast, immersing steel in a caustic solution or a hot water bath does not serve the intended purpose of removing surface contaminants as effectively as the acidic pickling process. Similarly, while biocidal solutions are used for different applications, they do not facilitate the removal of rust and scale in the manner that pickling does. Thus, the use of hydrochloric or sulfuric acid is the distinguishing factor that accurately defines the pickling process.