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  • 1.  Humidifiers for winter

    Posted 01-07-2025 01:51 PM
    Hello friends,

    As a museum in Florida, and with the temperatures plummeting, we are experiencing low humidity in our galleries and were considering complementing with portable humidifiers. Does anyone have experience with this, and if so, any recommendations?


    YLVA ROUSE
    SENIOR CURATOR
    MOCA JACKSONVILLE 
    University of North Florida
    Jacksonville, Fl 32202




  • 2.  RE: Humidifiers for winter

    Posted 01-07-2025 03:50 PM

    Hello Ylva,

    Over my decades working in museums, I have had the opportunity to deal with most of the types of humidifiers in existence, but I have also had discussions with many conservators as to the needs of various kinds of objects regarding humidity control. That is too large a subject to review here, and of course it tends to involve examination of the building envelope, including walls, ceilings, and windows; some of the greatest dangers involve condensation and freezing inside the walls, though I am reasonably sure you ought not to have that occurring very often in Florida. You could have condensation without freezing, though, and that can be quite destructive in the long run. Although most of us tend to think of Florida as a humid place, that is certainly not always the case, but I would be interested to know the range of indoor relative humidity (RH) you have recorded in recent months and years.

    To answer your question (at last), if you are planning to use portable humidifiers, you must be prepared to fill them with water, as needed. That last phrase is important, because if the water supply runs out overnight or on a weekend, it is likely that the RH will begin to go down, and you may set up an up-and-down cycle of RH that could be more destructive to the collections than a steady, low RH. I doubt there is a way to determine the duration of a full tank of water, except through experience, and of course you will be carrying watering cans or buckets through gallery and storage areas.

    The first type of portable humidifier operates by evaporation inside the machine, usually with a belt or disc that passes through the water tank, with air blowing through or over it. Moist air wafts out, and minerals and perhaps other matter in the water stays behind. Thus, a certain about of muck can build up in the machine, and/or on the material that carries and releases the moisture; an interesting smell may develop. Eventually, getting rid of the foreign matter will be necessary. This process may be a bit messy, and you may wish to replace the water-bearing medium rather than attempt to clean it. There is a big advantage to this method of humidification, and that is that as the RH in the air rises, the rate of evaporation in the machine slows down. The overall RH may still rise if the controls -- often rather vague -- allow the machine to run longer than it should, but with any luck you might identify the situation well before the air is saturated.

    The other main type of portable humidifier creates either water vapor or a fine mist in the machine. In either case if the surrounding RH becomes too high, you can easily have water droplets falling from the air. In the case of the mist (or "nebulizer" or "atomizer") machine, any dissolved material in the water is blown from the machine whenever it is operating, since the tiny mist droplets actually evaporate in the surrounding air. This process can result in noticeable amounts of dust falling on flat surfaces. In the water-vapor, or "steam" machines, the dissolved material will not be emitted with the moisture, but it will build up in the machine, which will eventually need cleaning.

    I cannot recommend any specific model or brand of dehumidifier, but I think you will find a satisfactory assortment, and good service, from allergybuyersclub.com. If I may be of help, feel free to contact me at: abmacleish@verizon.net

    Best,

    Bruce

    Curator Emeritus -- Newport Restoration Foundation



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    Bruce MacLeish
    Curator Emeritus, Newport Restoration Foundation
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