[meteorite-list] Orange to green desiccant beads and chlorine content

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Wed, 2 Jan 2013 16:39:34 -0500
Message-ID: <CAKBPJW9EpeueCm4b+x0GGWYtgaz2qL-cOTbmYkGW69HcutSbmA_at_mail.gmail.com>

Hi Mendy and List,

I use "rechargeable" color changing dessicant packs in my specimen
cabinet. I have used them for years without any negative issues.
Each pack is sealed in a metal cartridge-like housing that is
perforated with holes. There is also a small viewing window to see
the color state of the dessicant. It changes from blue when dry, to
pink when saturated. On average, I recharge them about once every 10
days. Previously, I did it about once or twice a month, but now I do
it more often. My cabinet is not air-tight, and I live in South
Florida, so keeping the humidity down is a priority, but also a losing
battle. If I can reduce the humidity in the cabinet by 20-30%, then I
consider that a small victory. If I keep the cabinet closed and don't
open it frequently, the dessicant is more effective.

I think it is important to make sure the dessicant is not in direct
contact with the specimens and if possible, the dessicant should be
placed at least a few centimeters away from anything in the case or
cabinet.

Each cartridge I use holds approx. 50 grams of dessicant. and I have
about a half-dozen of them scattered about in my cabinet. I bought
all of them from the same vendor a few years ago, and can't seem to
find the link now. It was a coin and stamp supply store. Valley Coin
might have been the name, I am not sure.

Best regards,

MikeG

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On 1/2/13, Mendy Ouzillou <ouzillou at yahoo.com> wrote:
> Thank you Dr. Korotev.
>
> I wanted to make sure it was not an issue and, based on your response, does
> not seem to be especially since the chlorine is trapped int the beads which
> are never in actual contact with the specimen.
>
> Regards and happy New Year.
>
> Mendy Ouzillou
>
>
> ----- Original Message -----
>> From: Randy Korotev <korotev at wustl.edu>
>> To: Mendy Ouzillou <ouzillou at yahoo.com>
>> Cc:
>> Sent: Wednesday, January 2, 2013 11:20 AM
>> Subject: Re: [meteorite-list] Orange to green desiccant beads and
>> chlorine content
>>
>> Mendy:
>>
>> Methyl violet contains 8.7% ionic chlorine by mass, so that's 0.017%
>> "max" chlorine in the product you describe.  That compares with 64%
>> (!) chorine in common anhydrous calcium chloride desiccant, which often
>> contains
>> cobalt chloride.
>>
>> Silica gel without a coloring agent can be obtained.
>>
>> Randy Korotev
>>
>>
>> At 12:40 PM 2013-01-02 Wednesday, you wrote:
>>>  I've been researching the desiccant beads we typically use to draw
>> moisture away from meteorites and needed to ask a question from more
>> knowledgeable people on the list. These orange to green desiccant beads
>> are the
>> ones generally recommended as they supposedly do not contain chlorine.
>> http://www.desiccantpackets.com/pounds-loose-bulk-orange-indicating-silica-gel-desiccant-2-4-mm-beads-moisture-absorber-dehumidifier.html.
>>>
>>>  I asked the company specifically if the product contained chlorine and
>>> they
>> said no chlorine and no cobalt.
>>>
>>>  The composition is from the MSDS they sent is as follows:
>>>
>>>  Chemical Description: Orange to Green Indicating Silica Gel
>>>  Formula: SIO2 + H20 + C25H30CLN3
>>>  CAS (R Phrase Classification): 112926-00-8 amorphous silica 98.2%,
>> activated coloring agent 0.2% max.
>>>
>>>  The coloring agent is called methyl violet and the chemical formula
>>> clearly
>> shows chlorine is present. The amount is obviously very small but still
>> present.
>>>
>>>  Is this an issue? Is there a different desiccant that is also orange
>>> that
>> has no chlorine?
>>>
>>>  Thank you!
>>>
>>>  Mendy Ouzillou
>>
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Received on Wed 02 Jan 2013 04:39:34 PM PST