Imagine a metal that, when immersed in a solution, is cleaned of every imperfection, making it suitable for use in various sectors. This is the magic of pickling, a process of cleaning the surface layer of an object to remove all impurities and oxidation left by previous treatments.
Used in many sectors, from medical to construction, pickling is essential to ensure that materials are not only aesthetically pleasing but also functional and durable. Why subject metals to pickling? The answer, after these premises, is simple: to remove the oxidized layers that form during processing such as forging, rolling, and welding. These processes, although necessary to shape the metal, leave behind layers of oxides and impurities that can compromise the performance and aesthetics of the final product. So, pickling, as already mentioned, is not just a matter of aesthetics.
The methodologies applied by BAMA range from total immersion in acid baths to manual application via spray.
- Titanium – Also used for industrial purposes, titanium is widely used in the watchmaking, jewelry, and eyewear sectors. The pickling treatment of titanium can be done manually or by immersion in a tank containing various acids. An alternative to tank pickling is our Bama GelTitan Strong product, specifically for titanium alloys, which allows pickling even on tanks.
- Stainless Steel – Stainless steel is used in the food and agri-food sectors, as well as in the pharmaceutical and naval sectors. Pickling on stainless steel can be done manually using a brush, with the spray technique, or by immersion.
- Carbon Steel – The most frequently treated artifacts are prefabricated pipes for the passage of gaseous elements or for hydraulic use, but valves and tanks are also often treated. BAMA has developed a specific product for pickling carbon steel alloys, Bama Carbogel Quick, which should always be followed by a passivation treatment with alkaline or phosphoric solutions.
- Aluminum – Through aluminum pickling, it is possible to eliminate machining residues or uneven oxides on the surface of the aluminum alloy artifact (chips or rust formed during previous processing stages). The application of pickling products can be done with three techniques: spraying (with acidic or basic solutions), manually (useful technique to reach all hidden points of the object), and by immersion.
At BAMA, we also treat artifacts made of nickel and zirconium alloys through pickling.
How Pickling Works
The pickling process is based on chemistry: metals like stainless steel, aluminum, copper, and titanium are immersed in calibrated acid solutions to remove oxidized layers without damaging the underlying material. These solutions, rich in agents like hydrochloric, sulfuric, or phosphoric acids, react with the oxides, transforming them into soluble salts that are then easily removed from the metal surface.
For the most stubborn cases, for example when oxides resist chemical action, BAMA resorts to manual pickling using specific chemical products, such as Bama Gel Steel Strong or Bama Carbogel Quick, formulated as gels for better surface adhesion. These methods are ideal for large artifacts or on-site interventions, allowing us to offer flexibility and precision in treatment.
An Innovative Method Developed by the BAMA Spray Pickling
Always attentive to innovation, in recent years, our technical department has developed a new processing method: spray pickling and passivation. Among the main advantages offered by this technique are the reduction of the volume of pickling liquid used (compared to traditional immersion pickling) and the ability to use smaller amounts of pickling gels, thus reducing environmental impact and reaction times.
Moreover, the new procedure eliminates the need for manual application by the operator, avoiding potential risks associated with the use of aggressive substances.
Pickling, Passivation, and Electropolishing: A Winning Team
Pickling is a treatment that can be performed without further steps but gives its best when combined with other treatments such as passivation and electropolishing.
For example, passivation combined with pickling is a winning solution in light carpentry, meaning the treatment of artifacts with sheet metal less than 3 millimeters thick. Together, the two processes are complementary because they equip the metal with a protective shield against corrosive or atmospheric agents. This principle also applies to stainless steel, an alloy often chosen for its anti-corrosive characteristics but at risk of losing its function if not adequately treated. Passivation, in fact, favors and accelerates the natural creation of a protective chromium oxide film on the surface of stainless steel.
Electropolishing, in turn, can be combined with passivation and pickling treatments for optimal finishing results. It is a process based on electrolysis that adds further value to surfaces, improving the roughness profile and providing additional protection to the surface, giving a typical finish highly appreciated in industrial environments.
Choosing the treatments to be performed and the pickling methods requires experience and expertise: contact us for a consultation or a quote!
