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silica gel for moisture control?  RSS feed

 
drew msmith
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We use silica gel in our gun safe to keep things dry and rust free. We swap it out once a year as a precaution even though it's no where near saturated.  I was thinking I'd out scaled it up you might be able to avoid mold issues during the winter months.  It can be refreshed by heating it to 250 degrees for an hour or so and is also very cheap to purchase in bulk.
 
                                        
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Location: 5 Amandas Teal Dr,Bridgeville,DE 19933
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Upto what extent the moisture is been controlled by the above method ?
How long the things remain rust free ?
 
drew msmith
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ryan69beach wrote:
Upto what extent the moisture is been controlled by the above method ?
How long the things remain rust free ?


The silica gel is replaced yearly,  and the firearms have been rust free for quite a while now.  The gun safe is fairly small though. Maybe 50 to 75 gallons in capacity.  It would require some scaling up to be viable in a house,  but might be worth looking into as an unpowered way to dehumidify your indoors.
 
John Polk
steward
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Location: Currently in Lake Stevens, WA. Home in Spokane
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Silica gel is mis-named, as it is NOT a gel. Silica gel is simply silicic anhydride, SiO2.  Most of us are familiar with those little packets that come with cameras and high end electronics.  How much can it absorb?  Twenty (20) percent of its own weight.  One pound of silica gel can absorb 3.2 ounces of water from the atmosphere.

Those familiar packets we know in the US, that turn from blue to pink once they have absorbed their maximum water, have been outlawed in the European Union.

Here is a cut/paste from an article on long term seed saving @
http://www.seedcontainers.net/a_guide_to_long-term_seed_preservation.html

QUOTE:

The colour usually shown by silica gel is due to an indicator,
added to see directly when it is dehydrated and when it has absorbed moisture.
For many years, cobalt chloride (Cl2Co) has been used.
This substance gives the dehydrated gel a strong blue colour and a pale pink colour
to the gel having absorbed moisture. Recently, the European Union banned its use
because of considering it carcinogen through inhalation. A search for
new alternatives led to some iron salts, where the change in colour can be poorly
distinguished. At present, the most advisable alternative is methyl violet, which
gives the dehydrated gel an orange colour and a green colour to the hydrated gel.

END  QUOTE

As a side note, silica gel will also absorb some toxins from the atmosphere.  Given the reputed carcinogetic nature of the readily available form in the US, I consider it a "trade-off".  I have NOT researched price/availability of the methyl violet version in the US, but would suggest that you do so if you want to go this route for home use.

For reference, the "green" color they refer to looks more like olive drab to me.
Here are views of (L) untreated, (next 2) the type common in US, and (right2) the euro version.



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Ran Prieur
Posts: 66
Location: Spokane and near Diamond Lake, WA
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I've been using this trick for several years, mostly in a dead fridge that I use for storage on my land. I buy crystal cat litter, fill the foot parts of socks, and tie off the ankles to close them. On sunny days I'll stick them in the solar oven to drive the moisture out. Haven't tried the colored stuff -- I just guess at the water saturation. But now that I think about it, if you have a fixed quantity of silica, you could find out how much water is in it by weighing it.
 
                                
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Silica Gel is very safe and it NOT a "gel". It will remain a solid even when fully absorbed with moisture. It is used everyday in regular goods and even food. You will find in spices "anti-caking agent" which is normally Silica Gel powder used right in with the foods.

There is some Silica Gel that is BLUE in color that contains Cobalt Chloride. This stuff has been "which is classified as a IARC Group 2B carcinogen." (via http://www.silicagelpackets.com/indicating-silica-gel-packets/ ) so it would be wise to avoid this stuff or throw it away if you have it!

They seem to make other stuff that is Orange Indicating Silica Gel that does NOT contain Cobalt Chloride. Please use this!
 
a wee bit from the empire
The Earth Sheltered Solar Greenhouse Book by Mike Oehler - digital download
https://permies.com/wiki/23444/digital-market/digital-market/Earth-Sheltered-Solar-Greenhouse-Book
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