Camera Master, Print Master, Service Copy: Managing Microfilm Generations
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An archive that keeps only one copy of its microfilm has a single point of failure. The established practice is to keep three generations: a camera (preservation) master that is never handled, a print (duplicating) master used only to make copies, and service copies that readers and scanners actually use.
That simple rule is what lets a microfilm collection last for centuries while still being consulted every day. It also matters more now that many institutions are digitising their film: the scanner should be fed a duplicate, not the master. This guide explains what each generation is for, where third-party archival bodies such as the National Archives of Australia and Cornell University Library say each should be kept, which film types suit which role, and how a hybrid digital-plus-microfilm programme fits the same model. It applies to any archive, library, records centre or government agency running 16 mm or 35 mm roll film, wherever it is in the world.
The Three Generations of Microfilm, Explained
Microfilm generations are successive copies of the same film, each with a defined job. Cornell University Library's preservation tutorial describes three: "the camera or master negative, the print master negative, and the positive-use copy." The National Archives of Australia (NAA) uses slightly different names for the same structure: a preservation master on silver halide film, a duplicating master (also silver halide), and reference or working copies.
- First generation: camera master (preservation master). The film exposed in the camera or written by a digital archive writer. It is the reference point for every later copy and is stored, not used.
- Second generation: print master (duplicating master). A silver duplicate made from the camera master. Its only job is to produce further copies, so the camera master never has to come out of storage again.
- Third generation: service copies (reference or working copies). The rolls that go onto readers, reader-printers and scanners, and that get scratched, mis-threaded or lost over time.
The NAA notes that most standards and guidelines recommend all three, and that the minimum for archival purposes is "one master and one reference copy." Archives that can only afford two generations should treat the master as untouchable and accept that any future copy will come straight from it.
Where Each Generation Should Live
The preservation master belongs in a different place from everything else. The NAA states that the preservation master "should be kept in a different location to the duplicating master and reference copies. This should preferably be off site." Cornell's tutorial makes the same point: the camera negative "must be stored in a secure place remote from other film generations", in a fire- and flood-proof environment.
Third-party guidance differs on exact figures, so it is worth knowing the range rather than a single number:
| Source | Black-and-white masters | Reference / service copies |
|---|---|---|
| National Archives of Australia | 8 to 12 °C, 30 to 40% RH | 18 to 22 °C, 45 to 55% RH |
| Cornell University Library preservation tutorial | Constant 18 °C, 35% RH | Not specified |
For a formal specification, the relevant international standard is ISO 18911, which covers storage practices for processed safety photographic film. Both sources agree on the principles behind the numbers: keep masters cool, dry and stable, and keep them away from the working collection.
Enclosures matter as much as the room. The NAA advises archival-quality enclosures for master films, such as close-sealing polypropylene containers or cardboard that has passed the Photographic Activity Test (the enclosure requirements are set out in ISO 18902). It also says never to use rubber bands or sticky tape on film, never to apply labels directly to the film, and to use coated-metal storage furniture.
Which Film Types Suit Which Generation
Only silver-gelatin film is recognised for preservation masters. Cornell's tutorial is explicit: "Silver-gelatin is the only type recognized for preservation or archival purposes." The NAA describes diazo as "not suitable for long-term retention" and vesicular as "unsuitable for archival filming"; both are normally used for reference copies.
In practice that gives a simple rule:
- Camera master and print master: silver-gelatin film on a polyester base, processed to archival standards. Micrographics Data's MD-brand silver films (16MGD-HR and 35MGD-HR on a PET-125 base, and MGD33 for archive writers on a 5.0 mil base) are rated LE-500 to ISO 18901, with a resolution of 850 lines/mm, supplied in 30.5 m (100 ft) rolls.
- Service copies: silver duplicates where the copy will be handled heavily or kept for a long time. Diazo or vesicular copies are used where a low-cost, short-life reading copy is acceptable. Cornell notes that diazo can fade under UV light, and that pressure on vesicular film can damage its image-bearing bubbles.
Processing quality sets the ceiling for every generation. A camera master that leaves the processor with poor chemistry or incorrect washing will pass its faults on to every duplicate made from it, which is why processor maintenance and consistent chemistry (such as MD18c developer and MF18c fixer, used with processors like the Smart MD PRO5) are part of generation management, not a separate topic.
Generation Management in a Hybrid Digital and Microfilm Programme
A hybrid programme applies the same three-generation logic to digital files and film together. Many archives now create microfilm from born-digital or scanned images using a digital archive writer such as the MD AW3, which writes to 16 mm or 35 mm film from any brand at 150 lp/mm. The roll that comes off the writer is the camera master and should be treated exactly like a camera-exposed original: processed, inspected, duplicated, then stored off site.
The reverse workflow follows the same rule. When an archive digitises existing microfilm, the scanner should be fed a print master or a service copy. The NAA's guidance that masters "should not be used for reference purposes" applies to scanners as much as to people at a reader, because every pass through a transport risks scratches and handling damage.
Three practical checks keep a hybrid programme honest:
- Record which generation each roll is, on the container and in the catalogue, so a master is never issued by mistake.
- Survey holdings regularly. The NAA recommends programmed surveys of film holdings to detect problems early, including the development of redox blemishes.
- Keep the digital files and the film masters in separate places, so a single fire, flood or cyber incident cannot take out both.
Micrographics Data's microfilming and digital-to-microfilm services and microfilm scanning services are organised around this separation of masters and working copies.
Frequently Asked Questions
How many generations of microfilm should an archive keep?
The National Archives of Australia notes that most standards and guidelines recommend three copies: a preservation master on silver halide film, a duplicating master also on silver halide film, and reference or working copies. Its stated minimum for archival purposes is one master and one reference copy.
Can the camera master be used on a reader or scanner?
No. The National Archives of Australia says silver halide masters should not be used for reference, and Cornell University Library's preservation tutorial states that under no circumstances should the print master negative or the camera negative be used by readers. Day-to-day viewing and digitisation should use a duplicate.
Where should the preservation master be stored?
Separately from the other generations. The National Archives of Australia advises keeping the preservation master in a different location from the duplicating master and reference copies, preferably off site, in archival-quality enclosures.
Are diazo and vesicular films suitable for preservation masters?
No. Cornell University Library describes silver-gelatin as the only film type recognised for preservation or archival purposes. The National Archives of Australia describes diazo as not suitable for long-term retention and vesicular as unsuitable for archival filming; both are normally used for reference copies.
What storage conditions do national archives recommend for black-and-white microfilm masters?
Recommendations vary by institution. The National Archives of Australia recommends 8 to 12 °C and 30 to 40 per cent relative humidity for black-and-white material, while Cornell University Library's tutorial gives a constant 18 °C and 35 per cent relative humidity for master negatives. ISO 18911 sets out storage practices for processed safety photographic film.
Request a Quote for Archival Microfilm and Supplies
Whether you are setting up a three-generation programme for the first time or replacing discontinued film for an existing one, Micrographics Data can advise on film, chemistry and equipment for each stage. Browse microfilm rolls and processing chemistry or digital-to-microfilm equipment, then Request a Quote. Supplied from Singapore; availability and delivery dates confirmed on each quotation.
Contact: sales@micrographicsdata.com | +65 6472 7255
Sources: National Archives of Australia, "Preserving microforms" (naa.gov.au); Cornell University Library, Preservation Tutorial, "Microforms" (chinapreservationtutorial.library.cornell.edu); Utah State Archives, "Micrographics: Duplicating Microfilm and Microfilm Storage" (archives.utah.gov).