Combined Pickling and Passivation
A combined chemical process in which disruptive oxide layers are removed and the passive protective layer is established in a single operational step. This minimizes processing effort for stainless steel components.
When welding stainless steel, the protective oxide layer burns off in the heat-affected zone. You can see it by the blue or brown discoloration. That's scale, which ruins corrosion resistance. With pickling, you apply an acid paste or gel that etches away this scale. Then rinse the part thoroughly with water. Only through pickling does the chromium layer come back to the surface, protecting the steel from rust. Don't leave the pickling agent on too long, or it will eat into the material. Always wear gloves and safety glasses when working; the acid is aggressive. After rinsing, the part should look clean and uniformly matte – then you've done everything right.