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Thread: Silica gel (may be off topic!)

  1. #1
    davidedric's Avatar
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    Silica gel (may be off topic!)

    Often, when I open a new piece of kit, a sachet of silica gel drops out (the last example was in a tripod!). Now, I know the idea is to keep things dry, but..... When I used to work in a lab, and we had to keep samples dry, usually, under vacuum, the gel might perform for a few days and then need to be dried out for re-use. I find it hard to believe that these little sachets in camera gear do any good whatsoever. Or does someone know differently?
    Last edited by davidedric; 6th February 2013 at 10:57 PM.

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    DanK's Avatar
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    Re: Silica gel (may be off topic!)

    Presumably, they do some good or manufacturers would not bear the expense, but I suspect that they are fully hydrated and useless either by the time the package is opened or soon after. I use these when I store my equipment in a sealed case in a very humid environment. They have a colorant that turns clear as the gel reaches its capacity. They can be recharged by heating them to 300 degrees Fahrenheit for a while.

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    Re: Silica gel (may be off topic!)

    Another option for obtaining lots of those little silica packages is to talk to your pharmacist and ask him/her to save some for you... I put a note up at work and had more than I could reasonably use in no time.

    Electronics going into long term storage get placed in a ziplock baggie along with several dessicant packs. The the whole thing goes inside another baggie again loaded with dessicant packs.

    Overkill perhaps, but I do live in a rainy climate....

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    Re: Silica gel (may be off topic!)

    The thing to do when gear has been out in the cold. To avoid condensation when returning gear to warmer temperatures, place everything in a ziploc with a bunch of dessicant packs.

    Great idea there Martin - will speak to a pharmacy about that.

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    CP140's Avatar
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    Re: Silica gel (may be off topic!)

    Thanks... couple words of warning... some of the dessicant packs may have activated charcoal instead of dessicant... they'll be blacker in colour (oddly enough) and should be discarded.

    Lastly... if you have allergies to any medications... don't handle any of the packs

    (oh, and don't lick your fingers after handling them hoping for a fun experience of dug induced psychelic experiences.... )

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    Administrator Manfred M's Avatar
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    Re: Silica gel (may be off topic!)

    A few comments - the silica gel desiccant is not poisonous or hallucinogenic. It is a special form of silicon dioxide (more commonly known as sand). That being said, it can be treated with other chemicals that might be poisonous, so I will heed the “do not swallow” warnings on the packages, just in case.

    The activated charcoal sachets that are sometimes included in packages have a totally different use from the silica gel. Many manufactured products emit odours due to off-gassing and these odours can accumulate in the packaging. This is especially true in plastic products. The charcoal absorbs the odours so that our newly purchased goods doesn't emit any unpleasant odours when we open the box.

    Bobo – when bringing gear in from the cold, you actually don’t need to put silica gel in the wrappings. The outside air is cold and dry and the condensation occurs when warm and humid inside air hits the cold equipment and condenses. If you wrap your gear before bringing inside any condensation will form on the outside of the wrapping and will protect the equipment from the condensation. Just don’t unwrap things until they have warmed up to ambient temperature.

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    Glenn NK's Avatar
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    Re: Silica gel (may be off topic!)

    Manfred:

    Good advice I think.

    When I lived in a much colder climate, fogging of lenses, cameras, eyeglasses, was a daily occurrence. For most of that time, the winter temps regularly dipped to -30 C (-22F).

    Fogging of eyeglasses was a nuisance easily removed when they warmed up. In fact it aided in cleaning them with a tissue or soft cloth.

    Cameras and lenses are a different matter - avoid fogging if at all possible as bacteria can actually grow on a lens - I've seen examples posted on other sites.

    The simple remedy I used (and still use) is to leave lens caps on, and leave all gear in the zipped up camera bag for an hour or two. The gear warms up slowly in the bag and moisture won't condense on the gear.

    I'm guessing that using zip-lock bags will soon be found to be an irritating nuisance. I certainly am not suggesting that they won't work - the theory is correct and they work very well, but I've never found them to be necessary. Re-drying silica gel packs for re-use may also be a nuisance not worth the bother. How many belts as suspenders is enough?


    Glenn

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    Re: Silica gel (may be off topic!)

    Thanks Manfred. Now I do not have to go beg for discards. hehe

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    Re: Silica gel (may be off topic!)

    Now I do not have to go beg for discards
    I wouldn't. You have no way of knowing whether they are still useful. They look the same regardless of whether they can still absorb water or not. If they really matter in a given circumstance, I would only use new ones (you can buy them sealed in plastic) or something with an indicator, like the Pelican ones. Otherwise, you could fool yourself into believing that you have protected your gear.

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    CP140's Avatar
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    Re: Silica gel (may be off topic!)

    Quote Originally Posted by GrumpyDiver View Post
    A few comments - the silica gel desiccant is not poisonous or hallucinogenic. It is a special form of silicon dioxide (more commonly known as sand). That being said, it can be treated with other chemicals that might be poisonous, so I will heed the “do not swallow” warnings on the packages, just in case.
    LOL... I wasn't suggesting the silica gel is a problem... but rather the trace amounts of medication that could be on the external packaging could be an issue if someone with a serious allergy handled the package.

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    Re: Silica gel (may be off topic!)

    Adding to the discussion from what I know (as a retired pharmacist)- THe little bags of silica gel in new equipment is only good until the packaging is opened- (funny that I have seen them still in the bottom of camera bags 20 or more years old.!)
    Silica gel crystals absorb moisture until saturated- so in a closed sealed environment they can 'suck' the moisture from cameras and lenses to help prevent fungus or mould growing on your valuable gear. They cannot continue to absorb moisture once saturated- left in the open they cannot absorb all the moisture in the world's atmosphere!. The good thing is they can be 'recharged' by drying using heat of some kind- I have used ovens, frying pans and microwaves. The best type of siclica gel crystals to buy have a colour indicator added that makes the crystals brilliant blue when dry (ready for use) and they turn pink as they become saturated with moisture.
    My use has been to place the blue crystals in air-tight containers with cameras etc, and when they have turned pink- microwave or frypan heat until dry once again. (use heat slowly to prevent crystals splitting).
    My wife has successfully used the same crystals to help her cake icing set on cakes- especially in wet weather- just enclose the crystals in an air-tight container with the cake.

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    Moderator Donald's Avatar
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    Re: Silica gel (may be off topic!)

    Quote Originally Posted by GrumpyDiver View Post
    A few comments - the silica gel desiccant is not ... hallucinogenic.
    Damn!

    Quote Originally Posted by wobert View Post
    Adding to the discussion from what I know (as a retired pharmacist)- ...
    One of the things I love about this forum is that you are always learning things.

    I'm one of the 'still in the bag after 20 years' people. Not because I didn't know that there was a saturation level, but because I didn't know what to do about it ... or that anything could be done, except keep buying more packets. I'm off to find those coloured cyrstals.

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