Explanation: http://www.vecom.co.uk/pickling.htm

"Pickling [...]
Pickling after the construction phase will restore the corrosion resistance to the same level as of the basic material. This is achieved by stripping the contaminated oxide layer via etching and allowing a new layer to form under controlled conditions, passivation.
[...]
Passivation:

[...]After pickling and complete removal of oxide scale/contamination, stainless steel will passivate spontaneously when exposed to air. [...] We accelerate this process and ensure the oxide layer reforms free from any contaminants. This process usually leaves the stainless steel with a *white* matt appearance."


The term "white pickled" is widely used in codes, such as the NORSOK STANDARD M-630, e.g. Material Data Sheet D41 for duplex stainless steel: "Surface finish: White pickled"


Example of usage in germany: http://www.scheco-ent.ch/produkte_bodeneinlau...

"Bodeneinlauf [...] Aus rostfreiem Stahl 1.4404 (V4A) gebeizt und passiviert."