Caring for Your Photographic Collections
Preventing Deterioration
Keep photographic materials at proper environmental conditions.
Relative humidity is the single most important factor in preserving most
photographic materials. Relative humidity levels above 60% will accelerate
deterioration. Low and fluctuating humidity may also damage them.
Conditions of around 68° F and 30-40% relative humidity are appropriate
and easiest to maintain in enclosed areas, such as an interior closet or
an air-conditioned room -- not in an attic or basement. High temperatures
and high relative humidity levels will accelerate deterioration.
Temperature, not relative humidity, is the controlling factor in the
stability of contemporary color photographs. Storage at low temperatures
(40°F or below) is recommended. Appropriate enclosures for cold storage
are available from various vendors.
Exposure to visible and ultraviolet (UV) light is potentially damaging
to photographs. Light can cause embrittlement, yellowing and color fading
in prints and hand-colored surfaces. Extended display of photographs is
not recommended; however if they must be displayed, use UV-filtering
plastic or glass in framing. Exposure of color slides to the light in the
projector should be kept to a minimum. Use duplicate slides instead.
Atmospheric pollutants, particularly sulfur compounds, will cause black
and white images to fade and discolor. Gas by-products given off by fresh
paint fumes, plywood, deteriorated cardboard and many cleaning supplies
may cause accelerated image deterioration. Storage in non-acidic
containers is recommended.
Handling Photographic Materials:
If photographs are handled improperly, they can suffer disastrous
damage, including tears, cracks, losses, abrasions, fingerprints, and
stains. Avoid touching fragile photographic materials; salts in human
perspiration may damage surfaces. Wear clean cotton gloves if possible
when handling negatives and prints.
Storage of Photographic Materials:
House photos in protective enclosures to keep out gritty dirt and dust
which can abrade images, retain moisture, and deposit contaminants. Avoid
and/or remove materials such as acidic paper or cardboard, polyvinyl
chloride (PVC) plastic, rubber bands, paper clips, and pressure-sensitive
tapes and rubber cement. Suitable storage materials should be made of
plastic or paper, and free of sulfur, acids, and peroxides.
Paper enclosures must be acid-free, lignin-free, and are available in
both buffered (alkaline, pH 8.5) and unbuffered (neutral, pH 7) stock.
Storage materials must pass the ANSI Photographic Activity Test (PAT)
which is noted in supplier's catalogs. Buffered paper enclosures are
recommended for brittle prints that have been mounted onto poor-quality
secondary mounts and deteriorated film-base negatives. Buffered enclosures
are not recommended for contemporary color materials. Paper enclosures are
opaque, thus preventing unnecessary light exposure; porous; easy to label
in pencil; and relatively inexpensive.
Suitable plastic enclosures are uncoated polyester film, uncoated
cellulose triacetate, polyethylene, and polypropylene. Note:
Photographic emulsions may stick to the slick plastic surface at high
relative humidity (RH); the RH must remain below 80% or do not use plastic
enclosures. Plastic enclosures must not be used for glass plate, nitrate,
or acetate-based negatives.
Prints of historic value should be matted with acid-free rag or museum
board for protection. Adhesives should not touch the print. Matting should
be done by an experienced framer or under the direction of a trained
conservator. See Handout: Guide to Preservation Matting and
Framing.
Store all prints and negatives that are matted or placed in paper or
plastic enclosures in acid-free boxes. If possible, keep negatives
separate from print materials. Store color transparencies/slides in
acid-free or metal boxes with a baked-on enamel finish or in polypropylene
slide pages. Commonly available PVC slide pages, easily identified by
their strong plastic odor, should never be used because of their extreme
chemical reactivity.
Place early miniature-cased photographs, including daguerreotypes,
ambrotypes and tintypes, carefully into acid-free paper envelopes and
house flat; keep loose tintypes in polyester sleeves, or, if flaking is
present, in paper enclosures.
Storage of family photographs in albums is often desirable, and many
commercially available albums utilize archival-quality materials. Avoid
albums constructed of highly colored pages. Never use commercially
available "magnetic" or "no stick" albums for the storage of contemporary
or historic photographic prints in black-and-white or color. These
materials will deteriorate quite quickly over time.
Prepared by Debbie Hess Norris, Photographic Conservator and Assistant
Director, Art Conservation Program, University of Delaware/Winterthur
[Excerpts of text taken from Caring for Your Collections: Preserving
and Protecting Your Art and Other Collectibles, The National Committee
to Save America's Cultural Collections; Arthur W. Schultz, Chairman.
Published in 1992 by Harry N. Abrams, Incorporated, New York.]
The preservation procedures described here have been used by the
Library of Congress in the care of its collections and are considered
suitable by the Library as described; however, the Library will not be
responsible for damage to your collection should damage result from the
use of these procedures.
Revised 12/98
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