Effective Preservation Techniques for Non-book Materials in Libraries

Walk into any modern library and you will find far more than printed books on the shelves. Microfilms, audio cassettes, video tapes, photographic slides, CDs, DVDs, and large collections of born-digital files now sit alongside the traditional collection. These non-book materials carry irreplaceable information, yet they are far more fragile than paper. A magnetic tape can lose its signal, a film can curl and fade, and a digital file can become unreadable when its format goes obsolete. Preserving them well is not about a single trick. It rests on three connected pillars: the physical environment, security against human threats, and sensible circulation policies. Get these basics right and you protect collections for decades.

The physical environment for preservation
Temperature control
Humidity control
Light control
Air quality and digital media
Security measures for non-book materials
Understanding the human threat
Technology-based safeguards
Controlled access
Developing circulation policies
The access versus preservation tension
The master and access copy model
Building a workable policy
Bringing the three pillars together

The physical environment for preservation

The single biggest factor in how long a non-book item survives is the environment it sits in. Films, tapes, and digital carriers are sensitive to heat, moisture, and light in ways that printed paper is not. Controlling these three factors slows down chemical, biological, and physical decay. According to the U.S. National Archives, the rates of chemical, biological, and physical deterioration increase as temperature and relative humidity rise, so keeping storage cool and moderately dry is the most cost-effective way to extend the life of a collection.

Temperature control

High temperatures speed up the breakdown of almost every material, while temperatures that are too low can make some items brittle or cause mechanical parts to fail. The right range depends on the material. For paper-based and mixed collections, a cool environment is generally recommended, with many institutions keeping storage between 18°C and 21°C (about 65°F to 70°F). Magnetic media follow a different rule. The International Association of Sound and Audiovisual Archives recommends storing magnetic tape in a temperature range of roughly 7°C to 13°C with relative humidity between 40% and 60%, kept away from strong magnetic fields.

An important warning applies to magnetic tape: colder is not always better. If tapes are stored too cold, the lubricant in the tape can separate from the base and ruin the recording, which is why storage below about 8°C is discouraged for audiotape. The lesson is that each format has its own sweet spot, and a single setting cannot serve an entire mixed collection equally well.

Stability matters as much as the exact number. Constant swings between hot and cold cause materials to expand and contract repeatedly, weakening them over time. Modern guidance has moved away from rigid set points toward acceptable bands, with the understanding that avoiding large fluctuations is often more important than hitting a precise figure.

Humidity control

Relative humidity (RH) is the second environmental lever. Too much moisture encourages mould growth, warping, and the breakdown of polymers used in tapes and discs. Too little moisture makes older film and paper brittle and prone to cracking. For photographic materials, the American Library Association recommends a relative humidity range between 30% and 50%. Mould is one of the most expensive problems a collection can face, so keeping humidity in check is one of the most valuable preventive steps a library can take.

One practical danger is condensation. When a cold carrier is suddenly brought into a warm, humid room, moisture forms on its surface. IASA guidance notes that temperature and humidity changes should be gradual, with the temperature gradient kept small and an acclimatisation period allowed when moving items between very different conditions.

Light control

Light, especially ultraviolet (UV) light, is a quiet but relentless threat. Photographic films, slides, and colour images fade and discolour with prolonged exposure, and the damage is permanent. All light is damaging to paper-based materials and leads to embrittlement, yellowing, and fading, all of which are irreversible. The safest practice is to store sensitive materials in the dark and bring them into light only when they are actually in use. When materials must be displayed, conservators recommend keeping low light levels and avoiding placement near windows or doors where intense sunlight reaches them.

Air quality and digital media

Airborne pollutants such as dust, soot, and gaseous contaminants also abrade and soil materials, so good air filtration supports the other controls. Digital media deserve a special note. A CD or hard drive can sit in perfect conditions and still become useless when the software or hardware needed to read it disappears. For digital collections, the environment is only half the battle. The dominant long-term strategy is migration, which means periodically transforming files into current formats as their original formats become obsolete. Storage and migration together keep digital content alive.

Security measures for non-book materials

Environmental control protects materials from slow, natural decay. Security protects them from a faster and more deliberate threat: people. Theft, mutilation, and careless handling can destroy in minutes what good storage preserves for years. Non-book materials are often compact, valuable, and easy to conceal, which makes them attractive targets.

Understanding the human threat

Library theft is not new, and the people behind it vary widely, from students avoiding copying costs to professional thieves seeking profit. Public libraries face a particular tension because their core mission is open access, yet that same openness creates risk. As one overview of the field puts it, the challenge is enabling free access to resources while still maintaining control over them. Recognising this tension is the first step toward a security plan that protects materials without locking out genuine users.

Technology-based safeguards

Several tools help libraries track and protect their holdings. Electronic article surveillance systems, in use since the 1960s, sound an alarm when a tagged item passes through the exit gates without being checked out. These systems are not foolproof on their own, but when combined with alert staff, theft can be reduced by as much as 80%. Radio Frequency Identification (RFID) tags, widely adopted since the early 2000s, go a step further by allowing items to be tracked and circulation data to be recorded automatically.

Closed-circuit television (CCTV) cameras placed at strategic points deter would-be thieves and help investigate incidents. For digital collections, security takes a different shape: encryption and password protection guard files against unauthorised access or alteration. Barcoding, ownership marks, and alarm tags add further layers of deterrence.

Controlled access

For rare or fragile non-book materials, the strongest protection is to limit who can touch them at all. Rather than open browsing, many institutions keep valuable items in restricted areas where only authorised staff or trained archivists handle them. This serves two purposes at once. It prevents theft, and it ensures that delicate items are handled according to proper preservation protocols, reducing accidental damage from fingerprints, oils, or rough treatment. The American Library Association’s special collections guidelines also recommend practical steps such as informing booksellers of a library’s collecting areas and reporting thefts promptly so stolen items can be recognised if offered for sale.

Developing circulation policies

The third pillar ties the first two together. A library exists to be used, yet every use of a fragile item carries a small risk of damage. Circulation policy is where the library decides how to balance access against preservation. A well-designed policy does not simply restrict everything; it matches the level of access to the value and fragility of each item.

The access versus preservation tension

Some non-book materials wear out a little every time they are played. Mechanical and magnetic carriers degrade with each replay, so archives try to keep playback of original items to a minimum. The traditional approach in broadcasting and national libraries was to hold at least two copies: one for everyday access and one untouchable copy reserved purely for preservation. As IASA describes, this practice of keeping a separate access copy and an untouchable preservation copy protects the master while still serving users.

The master and access copy model

Digitisation has made this separation far more practical. The modern workflow creates several versions of each item. The preservation master is a high-quality, lossless file kept for the long term and rarely touched. An access copy, which is compressed and reformatted for convenient use, is what users actually view or listen to. The California State University, Northridge library describes this layered model clearly, distinguishing the archival preservation master, the production master, and the compressed access file for online use.

This model resolves the central tension neatly. Users get full access through copies, while the fragile original is protected from wear. The Library of Congress applies the same principle on a massive scale, making digital access copies alongside preservation masters so researchers can have playback on demand without ever handling the originals. Making a digital copy also reduces the need to run obsolete playback equipment that could itself damage the media.

Building a workable policy

A sound circulation policy for non-book materials usually addresses a few practical questions. Which items may leave the building and which are reference-only? Who may handle originals, and under what supervision? How are fragile items requested, retrieved, and returned? Many archives treat a request for access as the trigger to prioritise digitising that item, so future users can be served by a copy. The policy should also set clear handling rules, such as the use of gloves for film and proper storage of tapes vertically in their boxes, so that even permitted use does not cause harm. Written, consistently applied rules give staff and users a shared understanding and remove guesswork from day-to-day decisions.

Bringing the three pillars together

Preserving non-book materials is rarely about heroic, last-minute rescues. It is about steady, preventive care across three fronts. The physical environment slows natural decay through controlled temperature, humidity, and light. Security measures guard against theft and careless handling through technology and controlled access. Circulation policies keep collections usable by separating fragile originals from the copies people actually use. None of these pillars works well alone. A perfectly climate-controlled vault is useless if items are stolen, and the strictest security is wasted if heat and damp destroy the collection from within. When libraries align all three, films, tapes, and digital files can keep telling their stories for generations to come.

What do you think? Which of the three pillars, environment, security, or circulation policy, do you think is hardest for a small library with a limited budget to manage well? And as more collections become born-digital, do you think format obsolescence will eventually become a bigger preservation threat than physical decay?

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PDF 📄

Table of Contents

The physical environment for preservation 🔗

Temperature control 🔗

Humidity control 🔗

Light control 🔗

Air quality and digital media 🔗

Security measures for non-book materials 🔗

Understanding the human threat 🔗

Technology-based safeguards 🔗

Controlled access 🔗

Developing circulation policies 🔗

The access versus preservation tension 🔗

The master and access copy model 🔗

Building a workable policy 🔗

Bringing the three pillars together 🔗