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D-31   June 2002

1

Introduction

Photographic film remains an important 
documentary material. The increasing quantity 
and value of microfilm records used in financial 
institutions, libraries, government offices, and 
industrial firms have focused attention on the 
care of such records to make certain that they 
last as long as possible.

The distinction between photographic film records 
intended for storage and those intended for use 
has not always been clear. Use or work copies 
are the predominant photographic records found 
in libraries or record centers and are subject 
to much handling due to their value as quick 
references. However, because of this handling, 
they are subject to dirt, abrasion, fingerprints, 
contamination with foreign materials, and 
exposure to excessive light, temperatures, and 
harmful atmospheric pollutants. As a result, these 
copies in daily use cannot be considered suitable 
for long-term preservation. For long-term storage, 
it is imperative to prepare duplicate copies that 
meet certain criteria, such as proper filming, 
duplicating, processing, minimum handling, 
controlled environment, and storage.

In general, the care needed for storing 
photographic records is similar to that for 
storing written paper records, although there 
are some requirements peculiar to the storage 
of photographic film.

The permanence of photographic records 
depends on the chemical stability of the film, 
how the film is processed, and the conditions 
under which the processed film records are 
stored. The stability of the film layers is 
determined in manufacture and processing, while 
storage is controlled by the user. This pamphlet 
discusses the composition and properties of 
black-and-white silver-gelatin, thermally 
processed silver (TPS), diazo, and vesicular films 
as they relate to film permanence. It also 
describes the essential requirements of good 
processing and storage practices.

NOTE: Refer to the latest revision of each ANSI or 

ISO Standard specified.

Definitions

To help understand storage requirements, 
the composition and structure of microfilm are 
described and definitions of commonly used 
terms are given.

1

 

Structure of a typical black-and-white negative film.

Acetate film—(acetate base) safety film with a 
base composed principally of cellulose acetate 
or triacetate.

Antihalation undercoat—separate layer of 
light-absorbing dye located between the film 
emulsion and the base to suppress light reflection. 
During processing of this film, the dye layer 
becomes transparent.

Base or support—a flexible plastic material that 
is coated with a thin, light-sensitive, image-
forming layer. The thickness of the base varies 
with different film types.

Dimensional stability—ability of photographic 
materials to maintain their original size and shape 
during and after processing and also under 
various conditions of temperature and humidity.

Emulsion—the image-forming layer. For 
unprocessed black-and-white silver-gelatin films, 
it is composed primarily of minute silver halide 
crystals suspended in gelatin. Exposure to 
light in a camera or printer causes no visible 
effect, but there is an invisible change which 
produces a “latent image.” To obtain a visible, 
usable image, the exposed material must be 
chemically processed.

For diazo and vesicular films, the sensitized layers 
are composed of light-sensitive diazonium salts. 
To obtain a visible, usable image with these films, 
the exposed material is heat-processed. Diazo 
films are typically heat-processed in the presence 
of ammonia.

For TPS films, the image-forming layer is typically 
silver halide and silver salts suspended in a 
polymeric binding.

Содержание D-31

Страница 1: ...Micrographic Quality D 31 Storage and Preservation of Microfilms ...

Страница 2: ...Low Humidity 5 Molecular Sieves 6 Humidity Control 7 Air Conditioning 7 Moisture Tight Containers 7 Humidification 8 Fungus Growth 8 Microscopic Blemishes 8 Toning 9 Chemical Contamination 9 Composition of Enclosure Materials 10 Paper 10 Plastic 10 Metal 10 Adhesive 10 Printing Inks 10 Theft Protection 10 Processing for Permanence 11 Silver Gelatin Films 11 Fixing Baths 11 Washing 11 Squeegees 12 ...

Страница 3: ...Nuclear Explosions 13 Time Capsule Storage 14 Handling and Filing Film Records 14 Interfiling 14 Inspection 15 Table 1 Applicable Standards for Microfilm 15 Table 2 Storage Life of Microfilms 16 Table 3 Storage Temperature and Relative Humidity 17 Summary of Requirements for Storage and Preservation of Records on Kodak Microfilm 17 Storage Facilities 17 References and Bibliography 18 ...

Страница 4: ...elatin thermally processed silver TPS diazo and vesicular films as they relate to film permanence It also describes the essential requirements of good processing and storage practices NOTE Refer to the latest revision of each ANSI or ISO Standard specified Definitions To help understand storage requirements the composition and structure of microfilm are described and definitions of commonly used t...

Страница 5: ...phthalic acid All safety films both acetate and polyester manufactured by Eastman Kodak Company meet these requirements This means that they are difficult to ignite and are slow burning All silver gelatin Kodak Microfilms on Estar Base when processed as recommended by Kodak meet the current specifications established by the American National Standards Institute Inc ANSI for films intended for use ...

Страница 6: ...e retrieved without significant loss when stored at 21 C and 50 RH For example LE 100 indicates that information can be retrieved for at least 100 years of storage Silver gelatin films have an LE of 500 thermally processed silver TPS have an LE of 100 years Extended term storage conditions storage conditions suitable for the preservation of recorded information on the majority of freshly processed...

Страница 7: ...h pressure to damage or explode the cabinet There is practically no danger of an explosion from the storage of either Estar Base or acetate base safety film under these conditions There are small amounts of organic materials in acetate film base as well as moisture which will expand under heat and under some conditions might generate slight pressure However such intense heat would be required on t...

Страница 8: ...ning in storage the humidity of the work area should not be markedly different from that of the storage area Very large humidity differences may lead to some physical distortion The best relative humidity for storage is the lowest that can be achieved practically and controlled reliably within the limits specified in ANSI PIMA IT9 11 1998 and ISO 189115 or their latest revisions High Humidity Stor...

Страница 9: ...otential film degradation agents such as moisture oxidants solvents and others when kept in close proximity with the films under confined storage 24 Therefore Eastman Kodak Company recommends the use of molecular sieves with triacetate and polyester based films to reduce the physical aging of films and increase the longevity of black and white images under confined storage It also prevents ferroty...

Страница 10: ...ckets is recommended as this is an efficient desiccant Chemically pure silica gel may also be used as a desiccant provided that filtration is used to remove particle layers larger than 0 3 micron See ANSI PIMA IT9 11 1998 and ISO 18911 19985 or their latest revisions Moisture Tight Containers If humidity control of the storage area is not possible the storage of film in moisture tight containers i...

Страница 11: ...ar or thermally processed silver films The Kodak Disaster Recovery Laboratory offers no charge evaluation of suspect microfilm and can be reached at 1 800 EKC TEST 1 800 352 8378 or 1 585 253 3907 Microscopic Blemishes Some processed silver gelatin microfilms in storage for two to twenty years have developed microscopically small colored spots or blemishes The fogged leader at the outside of the r...

Страница 12: ...shes mentioned above Typical contaminants are paint fumes peroxides nitrogen oxides hydrogen sulfide sulfur dioxide and similar gases If an area is to be painted any films stored there should be removed beforehand and should not be returned to the area for three months The removal of contaminating gases from the air requires special consideration 5 14 15 16 17 Contaminants can come from illuminati...

Страница 13: ...hic images can be damaged by adhesives incorporating impurities such as sulfur iron copper or other ingredients that might react with image silver or gelatin Pressure sensitive adhesives and ether linked products should be avoided Rubber based products such as rubber cement should not be used Not only might they contain harmful solvents or plasticizers but they might be compounded with photographi...

Страница 14: ...tion To make sure that there is enough time for the fixing reaction to be completed specific recommendations for each type of film should be followed Undeveloped silver halides are dissolved by the fixer as complex ions of silver and thiosulfate As the silver content of the fixer increases with processing the silver thiosulfate complex becomes increasingly difficult to wash from the film This can ...

Страница 15: ...not recommended for microfilm because some hypo eliminators contain oxidizing agents that can contribute to the formation of emulsion blisters and microscopic blemishes Residual Hypo Test The accepted criterion for adequate washing is the methylene blue method described in ANSI PIMA IT9 17 1998 19 IT9 17 1998 also describes the silver densitometric method which has been suggested by the Associatio...

Страница 16: ...ped methods for safeguarding vital records in the event of a war or a natural catastrophe Many keep their vital records in underground repositories located many miles from large metropolitan areas When microfilm is kept underground in caves mines tunnels subbasements or similar locations special care should be taken to make certain that there is adequate control of the relative humidity Film shoul...

Страница 17: ...n Do not wind different generic film types on the same roll or store them in the same container Diazo and silver gelatin microfilms should be stored separately before and after processing Diazonium salt gases emitted from Diazo microfilm pre and post process can be detrimental to silver gelatin microfilm Continual handling of film even under favorable conditions causes some wear but wear can be ac...

Страница 18: ... 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 A...

Страница 19: ... 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 d...

Страница 20: ...considered suitable for black and white silver gelatin thermally processed silver diazo and vesicular Kodak Microfilms Table 3 Storage Temperature and Relative Humidity NOTE If the storage temperature is sufficiently low or if the air where the film is to be handled is quite moist leave the film in its closed container until it warms up to approximate room temperature Otherwise condensation of moi...

Страница 21: ...ment ASHRAE Handbook New York American Society of Heating Refrigerating and Air Conditioning Engineers 1992 17 HVAC Applications ASHRAE Handbook New York American Society of Heating Refrigerating and Air Conditioning Engineers 1991 18 Refrigeration ASHRAE Handbook New York American Society of Heating Refrigerating and Air Conditioning Engineers 1994 19 Recovering Silver from Photographic Materials...

Страница 22: ...ent Imaging Rochester New York 14650 www kodak com go docimaging Kodak Eastman Estar and Prostar are trademarks of Eastman Kodak Company KODAK Publication No D 31 CAT No 811 6386 6 2002 Eastman Kodak Company 2002 Printed in U S A ...

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