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D-31 June 2002 15
Inspection
The potential life of photographic records depends
largely on atmospheric conditions—temperature,
humidity, cleanliness—and the manner in which
the film is used. If storage conditions are kept
within the limits suggested in Table 3, inspection
of an adequate number of properly selected lot
samples should be made at two-year intervals.
12
While extended-term records should definitely be
kept under the recommended storage conditions,
film records of medium-term value may have
more leeway in terms of storage humidity and
temperature. Where humidity is not controlled
closely, film should be inspected more frequently
than at two-year intervals; the intervals between
inspection should not initially exceed six months
and then, if no deterioration is noted, can be
extended but should not exceed one year.
Sometimes film inspection is considered too
laborious and costly and is neglected for many
years—occasionally with unfortunate results.
If it is not always possible to open every film
can or rewind every roll at the recommended
frequency, select a few rolls at random from
the film collection each month for examination.
This approach provides some protection at a
relatively small cost. If there is any indication
that film records are not keeping properly,
storage conditions should be improved and other
protective treatments given the film. Make copies
of films that show signs of deterioration because
deterioration, once initiated, is an irreversible
process that may be restrained, but not
terminated, by improving storage conditions.
Therefore, extensive and frequent inspections
should be made.
ANSI/AIIM standards and technical reports are
available related to the inspection of silver gelatin
microforms. An example can be found in
American National Standard: “Imaging Materials–
Processed Silver-Gelatin Type–Black and White
Film–Specifications for Stability.”
2
Table 1: Applicable Standards for Microfilm
*LE is for polyester-based
**LE is for acetate-based
Silver-Gelatin
Thermally
Processed Silver
(TPS)
Diazo Vesicular
Long Term
LE 500*
LE 100**
Long Term
LE 100*
Medium, Long
LE 100*
Medium, Long
LE 100*
“Safety Film Specifications” IT9.6/
ISO 18906
IT9.6/
ISO 18906
IT9.6/
ISO 18906
IT9.6/
ISO 18906
“Specifications for Microfilms on
Polyester Base”
and
“... on Acetate Base”
IT9.1/
ISO 18901
“Methylene Blue Method ...” IT9.17/
ISO 18917
“Specifications for Thermally
Processed Silver Microfilms”
IT9.19/
ISO 18919
“Specifications for Stability of
Diazo Films ...”
IT9.5/
ISO 18905
“Specifications for Stability of
Vesicular Films”
IT9.12/
ISO 18912
“Practice for Storage of
Photographic Film”
IT9.11/
ISO 18911
IT9.11/
ISO 18911
IT9.11/
ISO 18911
IT9.11/
ISO 18911