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Thread: Recommended Dry Box/Dry Cabinet Humidity Setting Guideline...

  1. #1

    Post Recommended Dry Box/Dry Cabinet Humidity Setting Guideline...

    Since this there has been a lot of interest lately in humidity settings for dry box/cabinet, for the benefit of everyone, I have copied the general/recommened Dry Box/Dry Cabinet Humidity Setting Guideline (from Bossmen) for your reference...


    45%RH~55%RH - Disks, magnetic belts, VCD, camera, lens, projectors, VCRs, Telescopes, films, negative, slides, microfilm, tapes, videotapes, antique books, oil paintings, stamps, coins, antiques, CD, LD, contruction maps, leather goods, industrial design maps.


    35%RH~45%RH - Precision instruments, electronic and electric wares, measurement tools, precise moulds, semiconductor products, electric capacitor, wolfram wires, EL, batteries, optics, platted membranes and element, trasistors, light source, PCB, detectors, electricity-chargers, precise bearings, salt plates, optical lens.


    35%RH below - Individual experimental agents, samples, filtering plates, standard products, seeds, flower powder, dried flowers and spices, ten products, coffee, dried food.

  2. #2

    Thumbs up

    To add, if you store you cam/lens in too low humidity, lubricants in your camera body and lenses may harden or bind, rubber parts may crack as a result extremely dry condition. Therefore as pointed out by Mocha, 45% to 55% RH work best for camera.

    Cameras work best if they are also exercised periodically, say every four to six weeks or so.

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    Question: If the hygrometer on the dry box shows 50/55% and a separate electronic hygrometer shows 35%, which should I believe?

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    get a third opinion borrow another hygrometer to compare :P

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    Quote Originally Posted by alangoh
    Question: If the hygrometer on the dry box shows 50/55% and a separate electronic hygrometer shows 35%, which should I believe?
    this is a real tough question, especially when the quality/accuracy of both are equally dodgy, unless the digital one is a professional device.

    *shrug* trust the one that comes with a 5-year warranty?

  6. #6

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    Quote Originally Posted by alangoh
    Question: If the hygrometer on the dry box shows 50/55% and a separate electronic hygrometer shows 35%, which should I believe?
    IMO, electronic hygrometer should be more accurate (provided they are made by reliable manufacturer). Analogue hygrometer has to be calibrated before they leave the factory, sometimes they are not. You could try the calibrating by using the method(s) below.


    Calibrating a hygrometer.
    If you have a analog hygrometer (the kind with a needle and dial) there are two ways to calibrate your hygrometer.

    1.)Place it in a moist towel. Take it out after 15 minutes. It should read between 98% and a 100%. Whatever the difference add or subtract in the future or adjust the settings thru the hole in the back.

    2.)You can opt for using a cap (using a coke bottle screw cap will work)take iodized salt and fill the cap. Next take just one or two drops of water and place them in the cap of salt. Put your cap in a plastic bag (ziploc) with with your hygrometer, seal the bag, and the next day your hygrometer should read 75% humidity. If it doesn't adjust accordingly thru the hole in the back.

    With digitals hygrometer they are electronically accurate usually within 1% and 2% with a good battery operating the hygrometer.

  7. #7

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    ....a more precise & elaborated instructions:


    Hygrometer Calibration

    Analog (dial-type) hygrometers are often shipped from the factory out of spec. To calibrate, you need plain table salt, a few drops of water and a Ziploc or see-through Tupperware container with a tightly fitting lid.

    Place about 1 teaspoon of salt in a small shallow open container, such as the cap to a jar. Add a few drops of water to the salt. You DO NOT want a solution or to dissolve the salt, only get it damp. Place the container with the salt solution in the Tupperware container. Next, place the hygrometer in the Tupperware container/Ziploc face down. This will allow you to view and check the reading of the hygrometer before you open the container. CAUTION - do not spill any salt or solution on your hygrometer! Place the lid on the Tupperware container making sure it fits tight. Allow to stabilize for at least 6 hours. Without opening the container, check your reading. It should read exactly 75%. If not, note the deviation and or adjust the hygrometer.

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    Thanks Mocha. The analog hygrometer has two holes at the back but does not seem to have any sort of dial, what should I look out for?

    By the way, I assume that it doesn't matter whether the moist towel is hot or cold, or does it?

    Thanks much.

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    Quote Originally Posted by alangoh
    Thanks Mocha. The analog hygrometer has two holes at the back but does not seem to have any sort of dial, what should I look out for?

    By the way, I assume that it doesn't matter whether the moist towel is hot or cold, or does it?

    Thanks much.
    Your analogue hygrometer should have a little screw like thing for you to turn with a tiny spectacle screw driver. You ought to calibrate with the salt method, more reliable.

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    Thanks. I will try that.

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