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Thread: Silica gel

  1. #1

    Default Silica gel

    Will silica gel stop absorbing water when the RH reaches a certain level?

    Because once the RH in my drybox reaches 48%... it doesn't drop anymore. Yet when I opened it up to check the silica gel it is bluish purple. Nowhere near pink.

    I used a hair dryer to get it more to blue than purple... and again the RH stops at 48%.

    So I'm just wondering... will a silica gel regulate the humidity by halting the absorption process?

  2. #2

    Default Re: Silica gel

    This sounds like some humidity equilibrium qns to me..

    Are you using an electronic drybox or just an air-tight container with silica gel?

  3. #3

    Default Re: Silica gel

    RH% will not affect silica gels absorption. Silica gel like tissue paper will absorb till it is saturated (pink in your case). However as the silica gel turn pink purple (60/40), the absorption rate slows down but will continue to do so. Not all silica gel will turn all pink (80/20) at best.

    Silica gel absorption efficiency is depending on surface area and amount. E.g a small seal container with 15% area filled with fresh silica gel will reach near zero RH.
    So you need to explain how much silica, how was it placed and drybox size. Normally I would not trust the cheap analogue hygrometer as they tends not to problem measure low humdity.

    It would be illogical to use hair dryer because once the hot silica turn blue and cools immediately, condensation kick in immediately on the container surface. The moment you pour the hot/warm silica back into the drybox, the whole box will be moist. Silica gel must be cooled in a slow semi sealed compartment where condensation does not occur immediately.

    If you still have doubts but do not wish to ponder further, just drop 2 packs of thirsty hippo packet form into the drybox. If you are curious to find out more, go to the film developer shop buy 500mg silica gel and put half into it (** remember put some plastic/foam sheet between the silica and equipment.)

  4. #4

    Default Re: Silica gel

    Quote Originally Posted by J-Chan View Post
    This sounds like some humidity equilibrium qns to me..

    Are you using an electronic drybox or just an air-tight container with silica gel?
    Air-tight container... bought for $23 from MS color.

    Quote Originally Posted by spheredome View Post
    RH% will not affect silica gels absorption. Silica gel like tissue paper will absorb till it is saturated (pink in your case). However as the silica gel turn pink purple (60/40), the absorption rate slows down but will continue to do so. Not all silica gel will turn all pink (80/20) at best.

    Silica gel absorption efficiency is depending on surface area and amount. E.g a small seal container with 15% area filled with fresh silica gel will reach near zero RH.
    So you need to explain how much silica, how was it placed and drybox size. Normally I would not trust the cheap analogue hygrometer as they tends not to problem measure low humdity.

    It would be illogical to use hair dryer because once the hot silica turn blue and cools immediately, condensation kick in immediately on the container surface. The moment you pour the hot/warm silica back into the drybox, the whole box will be moist. Silica gel must be cooled in a slow semi sealed compartment where condensation does not occur immediately.

    If you still have doubts but do not wish to ponder further, just drop 2 packs of thirsty hippo packet form into the drybox. If you are curious to find out more, go to the film developer shop buy 500mg silica gel and put half into it (** remember put some plastic/foam sheet between the silica and equipment.)
    Thirsty hippo... hmm... will those no-brand cheaper alternatives work? My mum uses those... she says they are cheaper than thirsty hippo...

  5. #5

    Default Re: Silica gel

    You really need to visit NTUC hypermart more often. They are only 2 brands (although 4 at least) with packet form that is consider home price. You go and figure with is cheaper.

    Quote Originally Posted by fterh View Post

    Air-tight container... bought for $23 from MS color.

    Thirsty hippo... hmm... will those no-brand cheaper alternatives work? My mum uses those... she says they are cheaper than thirsty hippo...

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