im a huge fan of pickling paste, get it from a welders supplies, its not cheap and is highly dodgy tackle but takes off all tarnishing, any rust contamination, and heat marks from welding. i bought a bottle when i made my nav frame as when i had finished it i cleaned the whole thing with a steel wire wheel - result was that it turned a nice orange colour!
dont forget that stainless is rust proof all the way through - dont be confusing it with a coating such as galv or chrome.
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