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Provide
a Moderate and Stable Storage Climate
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High
temperatures and relative humidities intensify and
speed up the chemical reactions that deteriorate
photographs. Fluctuations in temperature and
relative humidity contribute to the structural
breakdown of photo materials.
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Maintain
35% relative humidity with daily fluctuation of no
more than 2% (may need to be slightly higher if
books and manuscripts are stored in the same area).
Do not exceed 50%. Mold begins to grow at around 60
degrees relative humidity.
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ldeal
temperature is 66 degrees with no more than 2 degree
daily
fluctuation. 68 degrees is considered an acceptable
compromise for storage areas where staff are also
working. If possible, store color materials and
negatives at lower temperatures.
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Store
photos away from heaters, washrooms and water pipes,
and avoid storage in attics and basements.
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Use
humidifiers, dehumidifiers and air conditioners to
stabilize climate. Run constantly, 7 days a week, 24
hours a day.
Limit
Exposure to Light
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Exposure
to light contributes to fading and embrittling of
photos by triggering adverse chemical reactions.
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Ultraviolet
rays from sunlight and fluorescent lights are
especially damaging. Incandescent lights are better
for areas where photos are stored and displayed.
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Block
out sunlight from windows and use ultraviolet
filters on fluorescent light bulbs.
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Exhibit
copy prints in place of original photos. If
originals are used, minimize exposure to light as
much as possible (ex.: drape black cloth over photo
which can be lifted for momentary viewing, use U-V
filtered PlexiglasTm and sheeting in display frames
and cases).
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Do
not display black and white originals for more than
3 months. Display of color materials is not
recommended, except under very controlled conditions
and strictly limited periods of time.
Protect
from Pollutants in the Air
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Photos
should not be exposed to fumes or gases from
industrial cleaners, insecticides, fresh paint,
newly-laid carpet, automobiles, or electrostatic
copy machines (ozone). Remove photos from areas
prior to painting, recarpeting or furnigating and
wait a couple of weeks before returning them; this
will give fumes time to disperse. Use mild,
bleach-free cleansers to clean photo areas.
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Protect
photos from dirt and dust which can abrade image
surfaces and deposit harmful chemicals directly upon
the emulsion. Place photos in protective enclosures
and practice good housekeeping.
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Use
air filtering systems. (Non-electrostatic systems
preferable since they do not produce ozone.)
Protect
from Pests and Parasites
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Avoid
conditions that encourage growth of molds and fungus (high humidities, poor air
circulation), or provide enticements for insects and rodents (food, drinks, plants
in storage areas).
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Inspect
newly-acquired materials for infestations before
exposing to the rest of the collection. Isolate
suspect materials.
Use
Recommended Storage Enclosures and Equipment
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Wooden
shelving, cabinets and boxes are not recommended for photo storage since they
emit acid-fumes and peroxide gas as they deteriorate. If wooden cabinets and shelving
are the only alternative, they should be sealed with several layers of polyurethane
varnish, covered with a water-based acrylic paint, or lined with acid-free paper.
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Metal
cabinets and shelving should be made of rust-proof,
non-corrosive materials such as stainless steel, steel
with a baked-enamel paint finish, or anodized
aluminum. Regular commercial paper and cardboard,
being by-products of wood, are acidic and contain
residual elements from the manufacturing process which
can harm photos. Many plastic storage enclosures also
give off fumes that cause chemical reactions in photo
materials. Special products made from acid-free paper
and cardboard, and stable I tics (triacetate,
polypropylene, polyethylene, polyester) can be
purchased from archival supply companies.
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Many
photo albums on the market are constructed from
harmful adhesives, papers and plastics.
"Magnetic" albums, which feature plastic
sheeting over gummed pages, are especially damaging.
Albums and scrapbook made of acceptable materials are
available through archival supply companies.
Use
Care When Processing and Handling
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Cotton
gloves should be worn when handling photographic
materials to protect them from oils, salt and sulfur
present on human skin. At minimum, make sure that
hands are clean before handling, and avoid touching
the emulsion of the materials (the emulsion side of
a negatives is the dull, grainy side).
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Do
not use regular ink pens or felt-tips to mark
photos. Inks contain sulfur and can
"bleed" through photos or migrate to
adjacent materials. Use a soft-lead, No.2, pencil,
and mark only on the back of the photo. Special
marking pens can be purchased through archival
suppliers for marking on film or the backs of prints
which have waxy surfaces.
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Avoid
placing metal fasteners (staples, paper clips, etc.)
or rubber bands on photos. Fasteners can rust, tear
or indent photographs, while rubber bands can become
welded to emulsions.
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Do
not apply pressure-sensitive tapes, labels, liquid
glues or rubber cement to photos. While wheat and
rice starch pastes, or white solid glue sticks, are
more acceptable adhesives, it is still preferable to
mount photos using methods that do not bring
adhesives in direct contact with the photo (ex.: use
of archival mounting corners).
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