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16 D-31 June 2002
Table 2: Storage Life of Microfilms
NOTES:
(1) Expressed as thiosulfate ion.
(2) Specific limits have not been set—the recommended washing should be satisfactory.
(3) Dehumidification may be necessary even though automatic air conditioning is not practical.
Film/Type/Parameter
Anticipated Storage Life
Medium Term
(Minimum of 10 Years)
Extended Term
(Minimum of 100 Years)
Long Term
(Indefinitely)
Silver-Gelatin Films
Residual Hypo
Residual Silver Salts
(1), (2)
—
Not above 0.030 grams
per square meter (1)
Not above 0.014 grams
per square meter (1)
No more than perceptible tint by spot stain test.
All Films—
Storage Conditions
Temperature and
Relative Humidity
See Table 3
Air Conditioning Not necessary
unless film records
are subjected to
frequent or sustained
high humidity (3)
Essential—including slightly positive air pressure.
Air Purification Normal Must be free from airborne gases, dirt particles,
and other contaminants.
Enclosures Not necessary with
moisture control
and/or air conditioning
If proper humidity control is provided, plastic or
metal, unsealed, can be used.
If adequate humidity control is not available, only
metal or glass sealed containers are acceptable.