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Micrographics is a series of activities which record reduced images of documents, called micro-images, onto fine grain, high resolution photographic film in a manner that ensures their reproduction, retrieval, and preservation.
There are two broad types of micrographic processes:
This is the only film which is practical for use as camera film. Silver-gelatin film is the only film recommended for preservation of long-term records.
The emulsion layer in silver-gelatin film consists of silver halide crystals suspended in gelatin. The gelatin is made from the renderings of animals. There are several properties of this material that makes it ideal for its intended purpose.
Gelatin does present certain problems, however. It is easily scratched, and can be damaged by reader/printers. Gelatin is an organic compound, subject to bacteriological and microbiological attack.
Silver film may also be used for creating duplicates of camera film. Duplicates can be made of the same polarity or reversed polarity using silver-gelatin film. Silver-gelatin film is expensive, however, and it is usually more economical to make diazo film duplicates for use as working copies.
Diazo film is used exclusively for duplicate printing and is not made for use as camera film.
The blank diazo film is imprinted with the an image, exposed, by placing the camera (silver-gelatin) film in contact with the unexposed diazo film stock and then exposing both to a strong ultraviolet light. Diazo film is then developed thermally in an ammonia chamber to form a readable duplicate copy of the original camera film.
Diazo film is inexpensive and quite easy to use. Its fast duplicating speed makes it ideal for high volume or routine duplication of camera film.
Microfilm is produced in a variety of formats, or microforms. Microform is the generic term for the various formats microfilm comes in. It is important to select the most appropriate format for each microfilming application.
Microforms generally fall into one of two broad categories:
Roll microfilm is simply a length of microfilm rolled onto a spool. Roll film is usually 100, 125, or 215 feet long depending on the thickness of the film base, and either 16mm, 35mm, 70mm, or 105mm wide.
Unitized microfilm formats contain discreet units of information. The "unit" may be a single document image or a series of documents relating to a single case or report.
Although there are some variations, unitized microforms fall into two main categories.
Microfiche is a 105mm by 148mm sheet of microfilm, frequently produced on a step-and-repeat camera, which contains micro-images permanently arranged in a grid pattern. The sheets have a header at the top for eye-readable (no magnification required) identification. The headers may be color or digitally coded. Microfiche is particularly appropriate for case file applications which do not require updating.
Microfiche can also be produced by making a contact duplicate of microfilm jackets.
A variation on standard microfiche is Computer Output Microfiche (COM Fiche). In a typical COM application, digital information is either projected on a cathode ray tube and then photographed, or written directly onto film using a helium-neon (He-Ne) laser. The physical format of COM Fiche is otherwise identical to source document microfiche.
Similar to microfiche, a jacket is a 105x148mm plastic carrier with sleeves into which single images can be inserted forming a grid pattern of images. Either 35mm or 16mm images may be used. As with microfiche sheets, jackets may have eye-readable and/or color-coded headers. The ability to rearrange images within the jacket or add subsequent images to the jacket makes this format well suited for case file applications which require occasional updating. This process tends to be labor intensive and should be used only when the application is particularly well-suited to this format.
Not all records should be microfilmed. Physical characteristics of some records make them poor candidates for filming. But there are other considerations that will help determine whether or not specific records should be converted to microfilm.
Microfilm offers financial benefits when used properly.
Active office space is the least efficient and most costly place to store inactive records. For records that have short-term retention requirements (less than ten years), low-cost records center storage is the most cost-effective storage solution.
|Hard-copy costs (Contents of 4-drawer filing cabinet)||Office||Records Center|
|Storage equipment (Amortized)||$40||$3|
|Total annual cost||$2,120||$31|
|Microfilm System Costs|
|Total annual cost||$450|
It is clearly more cost-effective to store inactive records in a records center than in active office space. However, microfilm may be a cost effective alternative for some records in specific circumstances.
If you decide to use microfilm in your records management program you must decide whether to do it yourself or contract with a commercial service bureau. The University Archives works with the departments to develop and administer contracts for micrographic services through commercial vendors. Contact the University Archives for more information.
Proper storage of micrographic material is necessary to ensure that the film will last for the life span (retention period) of the records. The importance of proper storage of microfilm cannot be overstated. However, archival storage conditions alone will not guarantee the permanence of the film.
American National Standards Institute's published standard, ANSI - IT9.11, specifies storage conditions.
Short to medium-term film (a retention period of less than 20 years) shall be stored in a room with a relative humidity between 30 and 60%. Peak temperature shall not exceed 77° F; ideally it should be lower than 68° F.
Long-term film shall be stored in a room with relative humidity between 20 and 30%. Temperature may not exceed 70° F. Humidity and temperature should be monitored at all times.
Security film should always be viewed on a light table rather than a reader. Reader-Printers can scratch security film.
The Security Copy Depository (SCD) of the Oregon State Archives Division satisfies these requirements. The Services of the SCD are available to state agencies and local governments. Storage arrangements for security storage of permanent microfilm can be arranged through the University Archivist.
Though it is not necessary to hold user copies of microfilm to the same standards for storage and handling that security copies are held to, by following the guidelines for storage and handling of security film, you can maximize the life, and therefore the investment, of your agency user copies.
Administrative Rule requires any records with a retention period of greater than 10 years which are converted to microfilm to have a security copy of that film stored off-site. (OAR 166-30-070 (1))
Silver halide film should never be stored in the same room as diazo or vesicular film, nor should they be stored in separate rooms that share ventilation systems.
There are many advantages and benefits micrographics can provide as a part of your records management program. Microfilm takes less space, can provide record security, can provide rapid retrieval of individual records, can provide easy copy distribution, and can potentially produce cost reduction and/or improved records management effectiveness.
There are, naturally, some disadvantages as well. Delays, mechanical breakdown, quality control problems, and the volatility of the medium itself are problems that you may face if you use micrographics for records storage and retrieval. Vendor portrayals of micrographic systems and its possibilities have been, at times, overly simplistic and misleading. Consequently, expectations of microfilm have sometimes been unrealistic. A judicious examination of your records and what micrographics can do for them may lead to a decision NOT to microfilm. The real test of microfilm is in successful use, but each prospective application must be preceded by a careful analysis to determine if there is good justification to film.
Effective: January 1994
Adapted from the Oregon State Archives Records Management Manual (1994).