Understanding and Preserving Non-book Materials: From Films to Microforms

A modern library is no longer a place of paper alone. Walk into a well-stocked collection today and you will find film-strips, cine films, microfilm reels, magnetic tapes, gramophone records, and stacks of CDs and DVDs sitting alongside the books. These materials are grouped together as non-book materials, and they carry information that often cannot be found anywhere else – recorded interviews, historical newsreels, colonial-era newspapers, and rare audio performances. The catch is that each of these formats decays in its own way, and most degrade far faster than a printed book if left unattended. Understanding what these materials are made of, and how to store and handle them, is the difference between a collection that survives for generations and one that is lost within a decade.

Why non-book materials need special attention 🔗

Books are forgiving. A volume left on a shelf in reasonable conditions can last a century or more. Non-book materials are not so patient. They are made of films, plastics, magnetic coatings, and metal reflective layers – substances that react chemically to heat, moisture, light, and even the air around them. Many also depend on a working playback machine. A magnetic tape or an optical disc is useless if there is no equipment left to read it, a problem known as format obsolescence.

The categories of non-book materials in libraries are usually grouped as visual materials (still photographs, slides, film-strips, cine films, and video), audio materials (gramophone records, audio cassettes, and compact discs), and microforms. For preservation purposes, it helps to think of them in three broad families based on what they are made of: film media, magnetic materials, and plastic and optical materials. The care strategy for each family is different, and treating them all the same is a common and costly mistake.

Types of film media and their care 🔗

Film media use a flexible transparent base, usually coated with a light-sensitive emulsion, to hold images. This family includes film-strips, slides, cine films, and microforms. They share a common vulnerability: the base material itself can chemically break down over time.

Film-strips and slides 🔗

Film-strips are short rolls of 35mm film carrying a sequence of still images, once widely used in classrooms. Slides are individual mounted transparencies. Both are sensitive to light, heat, and humidity. Direct sunlight and fluorescent light accelerate the fading of dyes, so they should be kept in the dark when not in use. The recommended environment is cool and dry, with a relative humidity in the range of roughly 30-50 per cent. Too much moisture invites mould growth; too little makes the film brittle and prone to cracking. Slides are best kept in individual archival-quality enclosures, and collections can be grouped in acid-free boxes to prevent physical abrasion.

Cine films 🔗

Cine films are the motion picture stock used for cinema and home movies. Early cine film was made on a cellulose nitrate base, which is now largely obsolete because it is dangerously flammable and chemically unstable. Later films moved to a cellulose acetate base, which is safer but still suffers from a well-known problem called vinegar syndrome – a chemical breakdown that releases a sharp vinegar-like odour and warps the film. From the mid-1970s, manufacturers shifted to a more stable polyester base.

Because of their chemical fragility, cine films need cold storage. The National Film Preservation Foundation notes that lowering the storage temperature dramatically slows the onset of vinegar syndrome, with cooler categories such as 12°C and below offering far longer life than room-temperature storage. Films should be wound on inert cores, kept in vented containers, and inspected periodically for the tell-tale acetic smell that signals decay has begun.

Microforms 🔗

Microforms are greatly reduced photographic reproductions of documents, including microfilm reels and flat microfiche sheets. They are heavily used across Indian university libraries to preserve historical newspapers, journals, and government records, and they have one big advantage: black-and-white film on a polyester base produced from the mid-1970s onward has a life expectancy of 500 years or more under proper conditions. Older acetate microfilm, however, is still vulnerable to vinegar syndrome.

The Northeast Document Conservation Center recommends storing microfilm reels individually in boxes, held in place with a preservation-quality paper tag and a string-and-button tie rather than rubber bands, which contain sulphur and break down over time. Enclosures should pass the Photographic Activity Test; safe plastics include polyester, polyethylene, and polypropylene, but never PVC or vinyl. Microfilm is ideally housed in purpose-built steel cabinets, and master negatives should be kept off-site in a climate-controlled space. A typical recommendation is an air-conditioned room held around 20-22°C with relative humidity near 45-50 per cent.

Magnetic materials and preservation guidelines 🔗

Magnetic materials store information as patterns of magnetised particles on a coated plastic backing. This family includes reel-to-reel audio tapes, audio and video cassettes, and magnetic data tapes. They are among the most demanding non-book materials to preserve because they are vulnerable on several fronts at once: chemical breakdown of the binder, physical wear, and erasure from stray magnetic fields.

Types of magnetic media 🔗

Magnetic audio tapes range from open reel-to-reel formats to the familiar compact cassette. Video tapes such as VHS use the same basic principle on a wider, faster-moving tape. The backing material has changed over the decades, and this matters for preservation. Some older tapes used an acetate base prone to vinegar syndrome, while many modern tapes use a polyester base whose binder can absorb moisture and become sticky, a chemical reaction known as hydrolysis. The good news is that this stickiness is sometimes reversible by carefully baking the tape at low humidity before playback.

Environmental conditions 🔗

For magnetic tape, climate control is the single most important factor. The Library of Congress recommends that tapes needing preservation for at least ten years be kept around 18-21°C at 45-50 per cent relative humidity, with large fluctuations avoided at all costs. Interestingly, the usual rule that “colder is better” does not fully apply here. If tapes are stored below about 8°C, the lubricant in the tape can separate from the base and ruin the recording. Consistency matters more than chasing the lowest possible temperature.

Handling and storage 🔗

The U.S. National Archives sets out clear handling rules. Tapes should be stored upright in their boxes and never stacked flat on top of one another, which stresses the reel and the tape edges. Crucially, magnetic media must be kept away from anything that generates a magnetic field – loudspeakers, magnets, high-voltage lines, and surge protectors can all corrupt the recording. Tapes should not be left inside a player when not in use, and dust, dirt, and fingerprints must be kept off the surface, since a stray particle can be large enough to disrupt the delicate spacing between the tape and the playback head. Because playback equipment itself can damage a tape, conservators advise testing any machine on a worthless “dummy” tape before using it on a valuable item.

Plastic materials and their long-term preservation 🔗

The third family covers materials whose primary medium is a rigid plastic disc. This includes the grooved vinyl gramophone records that store sound mechanically, and modern optical storage such as CDs, DVDs, and Blu-ray discs that store data as microscopic pits read by a laser. Although these feel sturdier than film or tape, they have their own specific weaknesses.

Vinyl and grooved discs 🔗

Grooved discs carry sound in a physical spiral groove. Their main enemies are warping from heat and scratching or abrasion of the groove. The National Archives advises storing discs vertically – never stacked horizontally, which causes warping under the weight – in a cool, stable, low-humidity environment away from sunlight and pollutants. They should be handled only by the edges and the centre label, and kept in protective inner sleeves to guard the playing surface.

Optical discs: CDs and DVDs 🔗

Optical discs are layered structures: a polycarbonate plastic body, a thin metallic reflective layer, and protective coatings. They can appear rugged but are in fact among the most fragile media a library handles, susceptible to heat, sunlight, bending, scratching, and humidity. A surprising point is that the label side is often more sensitive than the shiny data side, because the reflective layer sits close to the top surface; a scratch there can destroy data permanently. If the metal layer oxidises through exposure to air, the information stored at that spot is lost.

The care guidance based on NIST research gives practical rules. Discs should be held only by the outer edge or the centre hole, never touched on the surfaces. Writing should be done only on the label side with a non-solvent felt-tip marker, never with a ballpoint pen, pencil, or solvent marker, and adhesive labels should be avoided because they can warp the disc or peel and tear the layers. Cleaning should be done in straight lines from the centre outward, not in circles, so that any scratch runs across tracks rather than along one.

For storage, the Preservation Self-Assessment Program notes that the U.S. National Archives recommends keeping discs upright in inert plastic or steel containers designed for the purpose, in a cool, dry space free of large temperature swings. A frequently cited target for long-term storage is around 18°C and 40 per cent relative humidity. For archival recording, discs with a gold reflective layer are preferred over aluminium or silver because gold does not corrode.

Finally, no disc is truly permanent. Manufacturers may quote lifespans of up to a hundred years, but some recordable discs have failed within just a few years. The realistic strategy, as digital preservation experts stress, is migration – periodically copying data onto fresh media and newer formats – combined with keeping working playback equipment available. Preservation of optical media is therefore as much about managing technology change as it is about controlling the storage room.

Bringing it together 🔗

The thread running through all three families is the same. Stable, moderate temperature and humidity matter more than extremes; light, dust, and pollutants must be controlled; materials should be stored upright in chemically safe enclosures; and handling should always be by the edges. Beyond the storage room, the long-term survival of magnetic and optical collections depends on a plan to migrate content to new formats before the old machines disappear. In a tropical climate like much of India’s, where heat and humidity work against fragile media, investing in climate control and a migration schedule is not a luxury but a basic requirement for keeping these collections alive.

What do you think? If your library could afford to climate-control only one collection – its acetate cine films, its magnetic tapes, or its optical discs – which would you prioritise, and why? And as playback machines for older formats grow rare, should libraries focus their limited budgets on preserving the physical originals or on migrating their content to new media?

References

1. https://en.wikipedia.org/wiki/Vinegar_syndrome
2. https://www.filmpreservation.org/userfiles/image/PDFs/fpg_6.pdf
3. https://www.nedcc.org/preservation101/session-7/7-preservation-microfilming
4. https://www.nedcc.org/preservation101/session-6/6storage-and-handling-of-media-collections
5. https://www.iasa-web.org/book/export/html/3816
6. https://en.wikipedia.org/wiki/Preservation_of_magnetic_audiotape
7. https://www.archives.gov/preservation/formats/audio-storage.html
8. https://digitalpreservation.lib.byu.edu/caring-for-discs/
9. https://www.framedestination.com/blog/storage/cd-dvd-archiving-care-and-handling-guide
10. https://psap.library.illinois.edu/advanced-help/av-opticalmedia