Silica Gel Desiccant packet use - - - WARNING !

[Gus Lazzari]

Hadn't used this particular Hasselblad body & lens for at least 2 years. Knowing that I wasn't going to use this combo, I stored the body & a black 50mm Distagon lens into an airtight bag along with a 'Desiccant packet' (North Carolina is a four season environment that is subject to humidity). Retrieving it to once again put it back into the rotation, I was horrified to see that a desiccant packet negatively reacted with the metal that it came in close contact with (see the provided images; paint fade, rust, corrosion and the removal of the black anodize treatment). 

Maybe someone out there understands technically why this corrosion occurred.

My guess is that the 'silica gel' material did indeed absorb moisture, but this moisture became concentrated into the desiccant material (it didn't leave the airtight ZipLock bag) and being so close to metal, corrosion was the result - - -

So a lesson learned and a BIG warning to anybody who employs this same naïve technique :

So, don't allow desiccant materials to make ANY contact with your valuable equipment !

Edited December 7, 2022 by Gus Lazzari
Misspell of a word.

[za33photo]

Ooooh - THAT HURTS , thanks for the tip , I did not think that this could happen.

 

[rick_drawbridge]

Ouch! Many thanks for bringing this to the attention of the Forum!

[gordon_yee]

There are several materials used as desiccants. I suspect the packet you used was not silica gel but one containing a salt:

List of desiccants - Wikipedia

Silica gel is pretty inert. I guess the lesson here is to only use a desiccant packet if you know for sure what the material is. Sorry about your 'Blad.

Edit: Gus, do you remember where your desiccant pack came from? Just found this:

Active Clay Desiccant, Clay Desiccant, Absorbent. - Shanghai Betpak Packaging Material Co.,Ltd. - ecplaza.net

Described as a clay-based desiccant.

Edited December 8, 2022 by gordon_yee

[robert_ante]

I avoid keeping equipment in airtight containers. Better to let air circulate. I also live in area with four seasons...lots of rain and snow..  Room dehumidifiers help. Keep some photo stuff in gun safe (which becomes air tight only in case of fire) fitted with small safe heater to promote dryness. Both guns and cameras require similar storage conditions.

[robert_ante]

instead of “promote dryness”,:should have written “promote proper humidity”. Too much dryness is bad for string instruments.

[Julio Fernandez]

Silica gel definitely does not react with metals. However a common dissicant for short term storage is calcium chloride, CaCl2. It will produce a salt solution as it absorbs humidity, and that solution would produce results like those you suffered. 
 

I live in a climate very similar to the Carolines and use a lot of silica gel packs. Never saw this issue.

[chuck_foreman1]

Wow.. I wouldnt have expected that.. but apparently it does happen.. I have lots of these around the selves to promoted dryness. Athough I have varied weeather conditions.... the window of high and lows is limited. It rarely goes below 0 celcius  or much above 30. As mentioned by one poster, I would also be leery of "air-tight" containers. Many and most of my cameras are in the never-ready cases...  (some love them - some hate them) they are bunched together in cabinets and shelves and I toss these bags of silica gel all around to insure ...or perhaps wishful thinking.. a dry environment.  My enemy is dust.. but it would probably be unwise to introdce humidifier etc. 
I've generally just collected these packets as different things ordered arrived so I definitley have a mixed bag so to say.. and I suspect now they're of different contents. I assumed "silica-gel" was ..well silica.. that there are variations is a surprise and thank you Gus for educating us .

 

[Farside]

It was brought up some time ago either here or another camera forum that dessicant packs, in doing their job, end up being moisture concentrators.

I've usually kept the ones with indicator colour-change crystals as they're invaluable for tipping you off, provided you inspect them often enough.

[glen_h]

That does leave the question, of whether your dessicant was dry before you used it.

 

It is a favorite to put CoCl2 in dessicants, which is blue when dry, and pink when wet.

(It is a favorite for invisible ink in kids' chemistry sets, too.)