One
of the facilities where I work has a mold problem every summer (actually two
have mold problems and a third has a leaky roof.) When you have older buildings you will have problems. I once lived in a house built in 1790
with a rock wall basement. The
cement flooring in the basement has been poured with a drainage trough in the
middle so that the water would flow out when it rained. Mold in the summer was a
nightmare. All you could do was
use a dehumidifier in the upstairs throughout the summer months, keep the
outside cellar door open, and not use the cellar for storage of anything that
would mold. One part of it did
work great as a root cellar for onions and such, but the mold was tough on the
furniture. I still have one chair
that smells like mildew and it’s been re-covered twice. Enough of happy reminiscences.
First
step, which I mentioned several times in the last post, is to figure out if you
have a problem and when. If your
heating and air-conditioning system draws air from outside as many do, chances
are you will have to work at keeping your temperature and humidity stable. Why
should you care? Well, high heat will dry paper and make it brittle, furniture
too as well as other objects.
Moisture causes swelling and quite often mold. Something you definitely want to avoid.
What
can you do to fix the problem? Well, museums and archives need to call in
experts who can address any problems with the HVAC system. One of my libraries has taken a
two-step approach. The first was
to install special devices on the HVAC system to keep the humidity at the
target range. The second was to
bring in industrial de-humidifiers to pull moisture from the air when the HVAC
system is not being effective. The
conditions in the archive have to be carefully monitored to prevent the
de-humidifiers from removing too much water vapor or causing a rise in
temperature from the heat they generate. Another step that helps is to change
filters often, especially if you drawing in outside air. Clean filters will help control the
mold spores and other particles in the air. The same is true at home. Change filters often.
Cleaner air is better for you, your possessions, and the heating and air
conditioning systems that you use.
Other dos and don’t for individuals and for museums and
archives.
1. As my story above suggests,
don’t store things in a basement.
No paper for
sure. Attics are terrible too because they can get too hot in the
summer and
cold in winter with abrupt
fluctuations in most places. Basements tend to
flood on occasion. Mine, the one I
told you about always did since I lived at
the bottom of a hill although the
worst flood I was in was in Lubbock, Texas
where it rarely rains. Everything on the floor of my
apartment experienced
water damage. I
still have books with wrinkled pages.
I guess the moral of
that story is never store anything
on the floor. Always have it up one
or two
shelves if you must store things in
the basement or in my case on the first
floor of my apartment. (Who knew semi-arid deserts would
flood? It
shouldn’t have, but the city pumped
water from one playa lake to save some
expensive homes to another lake
near me.) One of my libraries has just
moved their archives to the
basement. It hasn’t flooded but I have seen mold
on rugs and the coffee shop
upstairs has had leaky pipes on occasion.
Hopefully nothing bad will happen
and they will remember to keep things off
the floor. Of course, one of my other libraries
has their archives on the
second floor. In that case, the roof has been known
to leak. So far it has
leaked to the first floor with no
damage to the second. In that instance no
papers should be on the top shelf. Be aware of the limitations of your facility
is the best advice I can give and
be prepared for disasters.
2. Check your insulation to see if
it is adequate and fix any leaky doors and
windows. That will help stabilize the inside environment and
take some of
the stress from the HVAC system. Having insulated curtains can
help. Of course, archival storage
should be in a room without windows anyway. Remember light is damaging.
3. Keeping objects impacted by
temperature and humidity away from outside walls and windows is another
suggestion. A piano tuner told me that
pianos should be on inside walls to protect them from the impacts of the
outside environment. The same is true of other materials that are likely to
swell if the humidity is high or get brittle and crack when it is cold and
dry.
Lots have been written about temperature and humidity. Here are a few of the links that I have
used as resources.
Northeast Document Conservation Centers -
National Park Service –
(available
if the Republican shutdown of government ever ends)
Canada Conservation Institute –
Smithsonian (technical article) - http://www.si.edu/mci/downloads/reports/mecklenburg-part1-RH.pdf
Northern States Document Center –
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