Frequently asked questions
What is steel pickling?
Steel pickling is a treatment that is used to remove impurities, rust, and scale from the surface of a material. During hot processes, an oxide layer (scale) forms on the surface of the metal.
What is the process of pickling?
Metal surfaces can contain impurities that may affect usage of the product or further processing like plating with metal or painting. Various chemical solutions are usually used to clean these impurities. Strong acids, such as hydrochloric acid and sulfuric acid are common, but different applications use various other acids. Also alkaline solutions can be used for cleaning metal surfaces. Solutions usually also contain additives such as wetting agents and corrosion inhibitors. Pickling is sometimes called acid cleaning if descaling is not needed.
Many hot working processes and other processes that occur at high temperatures leave a discoloring oxide layer or scale on the surface. In order to remove the scale the workpiece is dipped into a vat of pickle liquor. Prior to cold rolling operation, hot rolled steel is normally passed through a pickling line so as to eradicate the scale from the surface.
The primary acid used in steelmaking is hydrochloric acid, although sulfuric acid was previously more common. Hydrochloric acid is more expensive than sulfuric acid, but it pickles much faster while minimizing base metal loss. The speed is a requirement for integration in automatic steel mills that run production at speeds as high as 800 ft/min (≈243 metres/min).
Carbon steels, with an alloy content less than or equal to 6%, are often pickled in hydrochloric or sulfuric acid. Steels with an alloy content greater than 6% must be pickled in two steps and other acids are used, such as phosphoric, nitric and hydrofluoric acid. Rust- and acid-resistant chromium-nickel steels are pickled traditionally in a bath of hydrofluoric and nitric acid. Most copper alloys are pickled in dilute sulfuric acid, but brass is pickled in concentrated sulfuric and nitric acid mixed with sodium chloride and soot.
In jewelry making, pickling is used to remove the copper oxide layer that results from heating copper and sterling silver during soldering and annealing. A diluted sulfuric acid pickling bath is traditionally used, but may be replaced with citric acid.
Sheet steel that undergoes acid pickling will oxidize (rust) when exposed to atmospheric conditions of moderately high humidity. For this reason, a thin film of oil or similar waterproof coating is applied to create a barrier to moisture in the air. This oil film must later be removed for many fabrication, plating or painting processes.
What is your largest vat?
6 mts x 5 mts 1.5 mts
Can you collect and drop off our products for pickling?
Yes, please get in touch for a quote and to book.
What is metal pickling
Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, precious metals and aluminum alloys.A solution called pickle liquor, which usually contains acid, is used to remove the surface impurities. It is commonly used to descale or clean steel in various steelmaking processes.