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I bought an used stainless steel really large pot (>90 liters) that was used for cooking, but had some kind of water stains inside.

On a (stupid) attempt to clean it, I had it sand blasted, which completely removed that nice, reflective surface that the stainless steel have, leaving an opaque darkish gray surface.

Is this fixable somehow, maybe by polishing or chemical treatment? If its not, is it still safe to use it?

Update. This is what it looks like now:

enter image description here

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Do you have some pictures? –  jards Sep 22 '14 at 2:55
    
You can get a mirror finish on stainless steel with sand paper. Use wet/dry paper, and lubricate with water. You'd have to start with a coarse grit (60? 100? Depends on what size holes the sand-blasting made), and move to progressively finer grits, 200, 400, 800, etc. ending around 2000 grit. If you stop at 400 or 800, you'll get a satin finish instead. It's a lot of work. You could probably use a power tool of some sort for the outside of the pot, but I can't imagine how to do this for the inside. –  Tobias Patton Sep 22 '14 at 14:17
    
Thanks @TobiasPatton. I will try that. Shouldnt that be an anwser instead of a comment? So that I can accept it if it works? –  romaia Sep 22 '14 at 19:52
    
You can get abrasive wheels and brushes for electric drills that should work well on the inside. –  TMN Oct 10 '14 at 15:15

5 Answers 5

up vote 1 down vote accepted

I have seen stainless steel handrails and pipelines fixed and welded on site, to get the finish back the guys use abrasive strips of varying grades until it shines. I imagine you only need to get the finish back to a point where there are no areas that bacteria could hide in the rough finish, so a satin finish should be fine and then make double sure with the sanitising before using the pot each time.

Hope this is helpful

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Thanks. I haven't had the chance to test this yet (as Tobias also sugested the same method), but when I do I will post the results (and accept the answer) –  romaia Oct 6 '14 at 21:10

I think you've ruined it. Sorry.

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Do you speak from experience? I mean, did that happen with you as well? I am questioning since Tobias gave some hopes for fixin it using sand paper. –  romaia Sep 22 '14 at 19:57
    
No, I don't speak from experience. I guess you have nothing to lose by trying. –  Denny Conn Sep 22 '14 at 21:14

If that was my kettle I would go with various grades of abrasive, in whatever form (powdered might also work), in progressively finer grades. Then, if the results looked halfway promising, I would use polishing compound and some sort of power buffing arrangement to put a mirror finish on the interior at least, or as close to a mirror finish as I could manage or stand.

I'm no metallurgist, but it's my understanding that the finer the surface finish, the less likelihood there is of (toxic) nickel leaching out of the stainless and into your brews.

[ edit/afterthought: long, long ago I had a closed stainless kettle fabricated by a welder who advised me to soak the interior with vinegar: in a kind of pseudo-pickling process. I don't know whether it did any good, but I figured it couldn't hurt, and didn't. ]

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I think that the pot is beyond redemption, unless you want to put many, many hours of labor into the project. Even with a powered buffer you are still looking at a couple of days labor. What is your time worth? Getting into where the side joins the bottom is going to be a special PITA. I would say scrap it or use it for a flower pot.

In the future, if I were to have such a problem, I would have the item soda blasted (essentially baking soda instead of sand) as the soda is a softer medium and therefore much less abrasive to the metal. It will also leave an almost satin sheen to the metal that is much easier to polish.

                       Cubrunrick
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Do you know what grade the material was? I believe this would be grade 202 or 304 as these cannot withstand lot of heat.

I would suggest you should not use this material as now the pot can get rusted and this may lead to problems later on.

Your best bet would be to try getting another pot instead because health concerns.

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