Cellulose acetate film, sometimes known as
safety film, was introduced in the early 1930s to
replace flammable cellulose nitrate stock. It does
not burn easily, however, warmth and moisture
cause chemical breakdown producing acetic acid
with its telltale vinegary smell, known as ‘‘vine-
gar syndrome.’’ The film base becomes brittle
and starts to shrink while the gelatin layer is
softened but remains otherwise unchanged and
the two start to separate, causing reticulation—
channeling and bubbling in the emulsion layer.
For small amounts of film stock or particularly
important images a professional conservator can
remove the emulsion layer and transfer it to a
new support, thus saving the image. However
prevention is better than cure—low temperatures
and recommended RH levels should be main-
tained and negatives kept away from acids, espe-
cially those found in unsuitable enclosures.
Material that is deteriorating should be removed
for treatment as vinegar syndrome can rapidly
spread to adjacent negatives.
Polyester supports are the most physically and
chemically durable—in fact the emulsion is more
likely to degrade—and simple to identify. Sand-
wich the image between two linear polarizing fil-
ters (available from camera shops) at right angles
to one another. Polyester film produces a ‘‘rain-
bow’’ effect similar to oil on water but acetate film
does not.
Film based negatives most often take the form of
single sheets in various sizes or strips, cut into
lengths of 4–6 frames. Storing negatives together
in a single envelope or box can cause scratches and
should be avoided. Negatives should be stored in
suitable paper or plastic enclosures, with the excep-
tion of nitrate film stock. As there is a danger that
toxic gases can be trapped in plastic sleeves, speed-
ing up the process of deterioration, paper enclo-
sures are preferable. Dampness in the air can be
trapped as moisture when sleeving negatives, and
care should be taken that this procedure is carried
out when the relative humidity is low.
Color Photographs and Negatives
Modern color photography was introduced in
the 1930s although earlier experiments, mainly in
additive processes, have been developed in the
nineteenth century. With the exception of the dye
transfer, color photographic materials are more
sensitive to high RH and temperature than black
and white photographs. Color materials are also
generally more susceptible to damage during hand-
ling and lint-free cotton gloves should always be
worn, with the image protected by plastic sleeves
for both casual viewing and storage. Hanging file
systems are ideal for transparencies as long as the
cabinets are not packed too tightly.Mounts and Albums
People have lovingly mounted their print collec-
tions in albums from the earliest days of photogra-
phy. Historically albums can be viewed as an
integral part of the photographic object and should
be treated with equal respect as the photographs
they house. Acid free tissue paper can be inter-
leaved between pages to protect images on adjacent
leaves, but take care that this does not put addi-
tional strain on the binding. The album should be
wrapped in conservation paper and stored flat in a
museum board box. Albums should not be stacked
on top of one another, as the pressure will damage
the lowest album. Neither is storing upright on a
bookshelf ideal as clasps and raised decorative
work can cause scratching and abrasion to adjacent
albums. Use a cradle to support the album and
prevent damage to the spine when viewing. Most
commercially available modern albums are not sui-
table for storing photographs, especially the type
with plastic adhesive sheets, PVC sleeves, or acidic
boards. Only conservation photo-corners and
hinges should be used for mounting prints.Conclusion
All of the above are essential in the prevention
of deterioration of photographic objects, however,
it is inevitable that objects will require treatment
at some stage. A qualified conservator should
always be consulted before treatment is carried
out. Surface dirt can be removed using a soft
brush, however, remember that dry cleaning is
abrasive and can result in scratches and image
loss. If absolutely necessary a Mars Staedtler rub-
ber can be used gently to remove dirt from the
surrounds and support, but do not attempt to
clean the image surface in this way, especially
with processes such as platinum prints where
there is no binding layer. The housewife’s tip of
using bread is definitely not recommended as
bread contains damaging oils. Wet cleaning proc-
esses should be approached with caution. Silver-
based images deteriorate in moist atmosphere and
gelatin emulsions become sticky. Because of this
mounts often have to be removed dry; however,
this destroys the mount, which can be an integral
part of the object. Alcohol based cleaning is also
suspect as the gelatin emulsion can swell. Profes-CONSERVATION