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What are
the relative advantages and disadvantages of using paper enclosures
to protect photographic materials?
Paper enclosures
are opaque, protecting the photograph from light. However, this
makes viewing difficult, since the photograph must be removed from
the enclosure before it can be viewed. This increases handling and
subsequent abrasion and fingerprinting of the image.Paper enclosures
are porous, protecting the photograph from the accumulation of moisture
and detrimental gases. This is especially important for cellulose
nitrate and early safety film negatives, since the gases generated
by the deterioration of these support materials are harmful to photographic
materials.
Paper enclosures
are available in buffered and non-buffered stock; both should be
of archival quality and non-acidic. Buffered storage enclosures
are not recommended for color images, cyanotypes, or albumen prints.
They are recommended for cellulose nitrate and early safety film
negatives, brittle prints and prints on brittle acidic mounts. Paper
enclosures should not be made of Kraft or glassine paper as the
impurities in these materials will cause deterioration of the photograph.
The cardboard boxes used by retail outlets to package photographic
materials should also be avoided.
What
are the relative advantages and disadvantages of using plastic enclosures
to protect photographic materials?
Plastic
enclosures have the great advantage of allowing an image to be viewed
without removal from the enclosure, greatly reducing the changes
of abrading, scratching, or fingerprinting the photograph.
Plastic
enclosures seal the object from the atmosphere. Since most chemical
deterioration in a photograph is catalyzed by the presence of moisture
and sulfides in air, such protection may prolong the life of the
image. However, plastic enclosures can trap moisture and cause ferrotyping
(sticking, with resulting shiny area) of the image under extreme
conditions.
Plastic
enclosures of archival quality may be made of polyester, polypropylene,
or polyethylene. Polyester is the most inert, dimensionally stable,
and rigid of the three. However, It can generate static electricity
which attracts dust, and it is very expensive. Polyester enclosures
should be either Dupont Mylar D® or ICI Melinex #516®. Polypropylene
is almost as rigid as polyester when it is the untreated "oriented"
polypropylene used in many sleeve formats, but is softer when it
is the surface-treated polypropylene used for ring binder storage
pages. Polypropylene enclosures perhaps provide the best balance
of safety and affordability, while maintaining excellent presentation
benefits. Low Density Polyethylene (LDPE) has a more translucent
clarity and was originally used in many ring binder storage pages.
LDPE pages are still the first choice of many, but it is the most
easily marred, and least rigid of these archival plastics. High-density
polyethylene (HDPE) is a very translucent, milky plastic which is
naturally slippery and is generally used for the low cost sleeving
on rolls provided by large photo processors.
It is our
opinion that plastic enclosures made from polyvinylchloride (PVC)
should be avoided for archival photographic storage. This plastic,
often-referred to as "vinyl" by suppliers, can be chemically unstable
and may cause deterioration of a photograph over time. Beware of
suppliers that avoid telling you exactly which plastics have been
used to produce their "archival" pages and sleeving.
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