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Subject: Mold


From: Richard A. Baker <richard.baker<-at->
Date: Monday, October 21, 2013
Nicole Prawl <nicoleprawl_234<-at->hotmail<.>com> writes

>I am currently in charge of our Bindery Department. I am a graduate
>of Simmons College and have a degree in Library Science with a
>concentration in Archives.  I am basically learning conservation as
>I go along on the job.
>Recently we had an outbreak of mold in one of our main reading
>rooms. It was controlled for a while and then it came back. ...
>...  We are trying to obtain a
>dehumidifier to extract some of the moisture from the air.  Which
>would be the best one to use in a tropical climate bearing in mind
>we turn off the air conditioners at night?.

We had an outbreak of mold in our small library that is located in
on the first floor of one of the house properties.  We immediately
set up a dehumidifier and ran it continually. The room also has
ceiling fans and we ran those constantly.  Doors to enclosed
bookshelves were open and all books were vacuumed using a
hepa-filter vacuum.  Freezing was not necessary in this instance,
though we do have a large capacity freezer for freezing collections.

Our museum is in Eastern North Carolina which is close to the
Atlantic Ocean and very humid during most of the year. It will dry
up a little during the late autumn and winter months.

Only a month ago, we discovered what was causing the continued mold
growth. Our mechanical maintenance technician discovered that the
air system in the basement was literally sucking up water from that
space and redistributing it throughout the air system.  He modified
the duct work so that would no longer occur.  The humidity has since
gone down in that space.  Of course we are now slowly moving into
the dryer season when humidity will not be as much of a problem.
Next summer will be the true test to be sure this was the only

Keep an eye on the books, specifically around the binding where mold
can hide.  We clean our books as mold is found.  We also have a Hobo
data logger in the room which I check every month.  Having a
mechanical maintenance technician on staff who checks all the spaces
daily is a big help to me.  He often knows about problems before I

I have posted on this forum in the past and recommended Danby
dehumidifiers. Since that time we have had one fail on us.  It was
in fact the one that was used in this library space.  Danby took
care of the cost to have it checked and re-imbursed us for the cost
of the product.  The issue was that it had run out of refrigerant.
We have since purchased two larger 65 pint Dayton dehumidifiers.
These work much better but I caution their use in areas that are
cooler. The devices have a defrost mode that if the temperature in
the room is too cool, such as from an air conditioner, it will
freeze up and spend time defrosting. The defrosting mode is louder
than the standard speed and can be a distraction during tours.  We
placed one in our Palace building which has problems with
temperature and humidity due to a very old HVAC system.  When the
temperature was lowered the dehumidifier would actually freeze up
and then we would find water leaking from it. This water was not
leaking from the collection bucket but from the ice in the unit
melting.  When the temperature is low enough to cause this sort of
condition in the dehumidifier I turn it off and remove it. The
Dayton that we have set up in the library is not freezing up because
the temperature is never cool enough in that space.

In addition to the Daytons we also have two Danby 45 pint
dehumidifiers and two older Craftsmen dehumidifiers.  These are used
throughout our site in original buildings, reconstructed buildings
and modern (built in 2010) museum properties.   Feel free to contact
me outside of the forum for more information.

Richard Baker
Conservation Specialist
Direct: 252-639-3542
Main: 252-639-3500
PO Box 1007
1New Bern, NC 28563
529 South Front Street
New Bern, NC 28562

                  Conservation DistList Instance 27:18
                Distributed: Thursday, October 24, 2013
                       Message Id: cdl-27-18-003
Received on Monday, 21 October, 2013

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