jgourlay
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Making mystery glass ware foodsafe?
Folks: is there a procedure for taking glassware of unknown contamination, and stripping it clean enough to be able to use it for food related
chemistry?
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querjek
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Wash it with acid, base, oxidant, reductant, and non-polars?
(please, don't take that too seriously)
it's all about chemistry.
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kclo4
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That is probably what you've have to do though. Clean it with a strong oxidizer such as piranha acid to get any organics, and then do something to get
any possibly toxic metal contaminants. I don't know how you'd go about doing that, perhaps EDTA(sp?) or a strong acid/base that could dissolve the
metal oxides.
You may also have to worry about contaminants that you'll introduce while cleaning it. Perhaps the NaOH you've used to clean it has some mercury
contaminants?
It probably isn't that big of a deal, I doubt there would be something so toxic, and horrible on the glass in enough quantity to do anything
noticeably bad to you. Assuming it doesn't have any residues and looks sparkling clean 
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hissingnoise
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If the contamination isn't visible run it through the dishwasher a couple of times.
If you can see it, get an angle grinder. . .
(please don't take that as seriously as querjek's solution(s))
Consuming the precipitate. . . interesting. . .
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woelen
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If the glass looks clean, then it should be OK to wash it with a mix of HCl(30%) and H2O2(30%) or HCl(30%) and bleach, which destroys organics. Next
put it in the dishwasher to get rid of the chlorine and then you should be safe eating from it.
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Globey
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All good suggestions. Picric in H2SO4, acidic dichromate as well. Even bleach. But if it's radio contamination, well then we don't know.
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Panache
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Simply wash it thrice (love that word) in whatever you intend to cook in it. For instance if you're intending a lovely little brew of Russian Caravan,
throw out the first three brews and enjoy the fourth knowing there will be little let to leach.
That is a joke.
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chief
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Worst case scenario would be: Glassware is from a radiochemical lab.
I would _never_ use any glass with lab-history for food ; but if I had to I would subject it to lengthy boiling in strong soda-solution, and also
NaOH-solution.
Then I would etch it with HF, boil in soda again, and repeat that procedure until I would feel safe about it.
The last step would be boiling 2 times with Soda, and in between once with HF, to remove any fluorides ...
This should work for most contaminated glasses ; but there are exceptions: Glass is possible to have electrolysis at Temps. as low as 200 Celsius ; if
such was done on it, then elements might have travelled deeply into it ...
And there is such a thing as glass-chemistry: A Glass with some contamination may be more "soluble" than one thinks (Sodium metasilicate as an extreme
example ...), and if that contamination would eg. be something very toxic, such as Beryllium (which may be a bad example for ingestion, but not
studied too far and at least _very_ poisonous for inhalation), then a smaller solubility might do some busines.
Also maybe the acidic solubility of such a contamination might be nonnegligible, eg. for juices ...
I wouldnt trust any lab-glassware of unknown contamination.
Also: Not every glass even contains any silicon, GeO2 as an example. Also Boron-glasse are known ... ; a whole world of glass-chemistry out there ...
[Edited on 12-4-2009 by chief]
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woelen
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Actually, I would not be as paranoid as chief. If I just think about it, how much contaminant could possibly be adhering to the glass. Most likely you
express that in micrograms or less. Even the most toxic substances hardly have any effect at those amounts. Also, there is no risk of long-term
exposure. If there were long-term exposure, then it would be so low that the natural background exposure to toxic substances is higher.
Just be sure that the glass really looks clean, do a wash with oxidizing acidic solutions (like the ones I suggested before) and a wash in the dish
washer to get rid of the chlorine remains.
Only exception I would make is when the glass could have been used for radioactive isotopes. These can be really harmful even in nanogram quantities.
But if you can be sure that the glass has not a radioactive history, then I see no real problem.
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Arrhenius
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Having worked extensively with radioisotopes, here is my thought on that. Very few labs use anything except 14C and 3H, both of which are
incorporated into organic molecules as radiotraces. In that light, you can wash these isotopes out of glassware exactly as you would a 'cold' organic
molecule. A flask containing 10^9 DPM 14C activity can effectively be cleaned to background by soaking in soapy water for several days, running
through a dishwasher and rinsing with acetone. Radioactivity isn't really appropriately expressed in nanograms, but I wouldn't be too scared about
ingesting 14C or 3H. Uranium, maybe, but not many people are cooking this up in their lab; not even at universities.
I don't know what edible something you might be thinking to produce, but if I were forced to eat out of a beaker using lab spatulas, this is what I
would do:
1.) Base bath with saturated NaOH in isopropanol (soak to get rid of organics + metals)
2.) Wash with hot soapy water.
3.) Rinse with acetone.
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Saerynide
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Mystery glassware make excellent smoking implements  Take it to parties and
everyone will agree you have the most awesome hookah 
"Microsoft reserves the right at all times to monitor communications on the Service and disclose any information Microsoft deems necessary to...
satisfy any applicable law, regulation or legal process"
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chief
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There is also such a thing as _inorganic_ radiochemistry ; and some of the elements used there are said to be quite nasty, going into everything ..
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jgourlay
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Gents, thanks for all the good answers. Some more pedigree on the piece and purpose. In the last issue of "Make" magazine, there was an article on
"vintage" coffee extraction. The process involved a thistle funnel, boiling flask, and beaker. It "works" but the coffee was crappy. However, it
was the "I can see potential" kind of crappy. The process was basically using heat to push water out of the boiling flask into the coffee, then using
the cooling of said flask to "suck" the coffee back in. The thistle funnel was used to give you something to wrap a coffee filter around inside the
beaker where the grounds were.
So I want to take a step further which would involve boiling flasks a, b, and c. "A" would be the water delivery and coffee receiving vessel. "B"
would be a "push" vessel to allow the coffee to stay hot while still being "pulled" and to leave less in vessel "C" which holds the thistle and
coffee. In this scenario, the ground container has to hold pressure (i.e., take a cork) but also has to have a large enough mouth to allow the
thistle funnel in.
All my glassware so far was purpose bought new and marked "FOOD ONLY" and kept in the kitchen. However, the only big mouth boiling flask I've been
able to find is from an ebay seller. She claims "my grand-dad was a compounding pharmacist, and I"m selling his estate. He always kept antique lab
glassware in a display case behind the register to impress the customers, and this piece comes from that collection."
So, who the hell knows? This thing could have never been used, or it could have been used to fractionate ichorated phlogiston....
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