The Impact of Inherent Material Qualities on Library Book Preservation

Every book on a library shelf carries the seeds of its own decay. Long before mould, insects, or careless handling get a chance to do damage, the paper, ink, and adhesives inside a book are already working against themselves. This is what conservators call inherent vice: deterioration caused by the very materials a document is made of, rather than by anything outside it. Understanding these built-in weaknesses is the first step toward protecting collections that are meant to last for generations.

What “inherent causes” really means 🔗

When we talk about the inherent causes of deterioration, we are talking about damage that comes from within the object. The Northeast Document Conservation Center describes inherent vice as deterioration caused by agents present in the materials themselves, as opposed to deterioration caused by external forces like light, humidity, or pests. These harmful agents may already exist in the raw materials, or they may be introduced during manufacturing.

This distinction matters for librarians. You can control the storage environment by adjusting temperature, blocking light, and keeping pests out. But you cannot change the chemistry that was baked into a book the day it was printed. A newspaper from 1950 will keep degrading no matter how perfect your storeroom is, because the problem is inside the paper. The best you can do is slow it down.

Paper quality and lifespan 🔗

Not all paper is created equal, and the difference comes down to what fibres it is made from and how those fibres were processed. For most of history, paper was made from cotton and linen rags. Rag paper is composed of long, pure cellulose fibres, and documents made from it centuries ago often survive in good condition today.

The crisis began in the second half of the nineteenth century. As demand for cheap printed material exploded, manufacturers switched from rags to wood pulp, which was far more abundant and inexpensive. According to Cornell University Library, because much of the world’s book paper after 1860 was produced from ground wood, libraries and archives now face a major preservation crisis. The shift made books affordable for everyone, but it came at a hidden long-term cost.

The trouble with wood pulp 🔗

Wood pulp paper has two built-in problems. First, the fibres are short and weak, which makes the paper less durable from the start. Second, and more seriously, wood naturally contains lignin, the substance that gives trees their rigidity. The University of Illinois Preservation Self-Assessment Program explains that lignin generates acid as it deteriorates and causes paper to yellow and become brittle when exposed to heat and light.

This is why an old newspaper turns yellow at the edges and crumbles when you touch it. The lignin is reacting to light, releasing acid, and attacking the cellulose fibres that hold the page together. Cheap papers like newsprint and groundwood are often made without removing the lignin, which is exactly why they are the fastest to fall apart.

Impact of sizing and pulp types 🔗

The fibre source is only part of the story. The chemical processes used to turn pulp into usable paper introduce their own dangers, and one of the biggest culprits is sizing.

What sizing does and why it became a problem 🔗

Sizing is a treatment that fills the gaps in paper so that ink does not bleed and feather across the page. Early papermakers used gelatin made from animal hides, which was relatively stable. But as production sped up, manufacturers adopted a cheaper alternative known as alum-rosin sizing. The NEDCC notes that alum-rosin sizing was widely used by the 1840s, and in the 1870s an even cheaper and more acidic version was developed.

The problem is that alum-rosin sizing makes paper acidic. Combined with lignin from wood pulp, it creates a chemical environment that steadily destroys the paper from the inside. The official international standard for permanent paper, ISO 9706, points directly to acidic materials such as rosin-alum size as a cause of the deterioration seen in modern documents.

The chemistry of self-destruction 🔗

Paper degrades chemically through two main pathways. According to the Royal Society of Chemistry, these are acid-catalysed hydrolysis and oxidation. In hydrolysis, acid acts as a catalyst that breaks the long cellulose chains into shorter pieces. As these chains snap, the paper loses strength and becomes brittle. In oxidation, the cellulose and lignin react with oxygen, which also cuts the chains and yellows the paper.

What makes this especially dangerous is that the process feeds itself. As documentation on mass deacidification describes, environmental pollutants react with paper to form acids, and the deterioration creates even more acid as a by-product, producing a self-accelerating loop of destruction. This is why conservators sometimes call acidic paper decay a “slow fire”: the page is essentially burning itself up over decades.

Chemical versus mechanical pulp 🔗

There is a clear hierarchy of paper quality based on how the pulp was made. Mechanical or groundwood pulp simply grinds up the whole tree, lignin and all, producing weak, acidic paper. Chemical pulp, on the other hand, uses processes that dissolve and remove the lignin, leaving purer cellulose behind. The Cornell tutorial confirms that lignin can be removed from wood pulp through chemical treatment, particularly the sulfate process. Paper made from purified chemical pulp lasts dramatically longer than its groundwood cousin.

The scale of the brittle books problem 🔗

The consequences of these material choices are staggering when measured across entire collections. In the early twentieth century, librarians realised that books printed since the 1850s were quietly turning to dust. The pioneering chemist and conservator William J. Barrow introduced the library world to the idea of treating paper acidity through deacidification by alkalisation.

Barrow’s findings were alarming. Research summarised in the literature on mass deacidification found that no more than three percent of books published between 1900 and 1949 would survive more than fifty years in usable condition. A single chemistry decision made in the paper mill had effectively given millions of books a hidden expiry date. This realisation triggered surveys and preservation programmes in libraries worldwide.

Remedies for material weaknesses 🔗

If the problem is built into the paper, then the most powerful long-term solution is to make better paper in the first place. This is where librarians and information professionals have a real role to play, not just as caretakers but as advocates.

Advocating for acid-free and permanent paper 🔗

The solution to acidic decay is paper that resists acid. Acid-free paper yields a neutral or slightly alkaline pH when tested, and it is free of lignin and sulfur. To go a step further, manufacturers add an alkaline reserve, usually calcium or magnesium carbonate, which actively neutralises any acid that forms later from ageing or pollution. The ISO 9706 standard sets out exactly what permanent paper requires: a minimum tear strength, a minimum alkali reserve, a maximum amount of easily oxidised material measured by the kappa number, and acceptable pH limits.

Librarians can use their purchasing power and professional voice to push for these standards. When ordering printed materials, requesting that important publications be produced on paper meeting ISO 9706 or its archival counterpart, ISO 11108, ensures that what enters the collection today will not become a preservation emergency tomorrow. Paper meeting these standards is often marked with a circled infinity symbol (♾), a quick visual signal of permanence.

Knowing the difference between labels 🔗

Not every “acid-free” claim is equal, and librarians should know the distinctions. The University of Illinois PSAP distinguishes between conservation-grade paper, which is wood-pulp-based but buffered to be acid-free, and archival-grade or museum-grade paper, which is made from cotton rag pulp and is the most durable of all. Knowing which grade is appropriate for which material helps allocate limited budgets wisely, since the most valuable items deserve the highest grade.

Preservation strategies for paper-based materials 🔗

Better paper helps future collections, but libraries are already full of acidic books and newspapers that cannot be unmade. For these, a mix of proactive strategies can extend their useful life considerably.

Deacidification 🔗

The most direct chemical remedy is deacidification, which neutralises the acid already present in the paper. As the Royal Society of Chemistry explains, this typically involves washing the paper in a mild alkali such as calcium hydroxide or magnesium bicarbonate. The treatment does two things: it neutralises existing acid and leaves behind an alkaline reserve to fight future acid formation. However, this is delicate, expensive work that should only be carried out by trained conservators, since improper treatment can damage inks and annotations.

Protective enclosures and storage 🔗

For most collections, the most economical preservation measures are preventive. The Library of Congress advises that for inherently acidic newspapers, proper storage and handling are the most effective and affordable steps, supported by acid-free and lignin-free buffered folders or flat boxes. Storing fragile items in buffered enclosures isolates them from pollutants and slows their decay. Oversize and brittle items are best stored flat rather than folded, since folding fractures already-weakened fibres.

Controlling light, heat, and handling 🔗

Because heat and light accelerate the chemical reactions inside acidic paper, keeping collections cool, dark, and stable directly slows their internal decay. Light damage in particular is cumulative and irreversible, so limiting exposure protects vulnerable items. Careful handling reduces mechanical stress on brittle pages, and even something as simple as clean hands matters, since acids from skin can transfer onto paper surfaces.

Reformatting and digitisation 🔗

Some books are simply too far gone to save in their original form. For these, the priority shifts from saving the object to saving the information it carries. Microfilming and digitisation allow the content to survive even when the physical page cannot. Given the sheer scale of the brittle books problem, libraries must triage, identifying the most valuable and endangered items and reformatting them before the paper crumbles entirely.

Putting it all together 🔗

Inherent deterioration is a reminder that preservation begins long before a book reaches the shelf. The fibres chosen, the pulping method, and the sizing chemicals all decide how long a document will last. Wood pulp and alum-rosin sizing gave the world cheap, accessible print, but they also planted acid and lignin inside every page. Librarians who understand this chemistry can respond on two fronts: advocating for permanent, acid-free paper in new materials, and using deacidification, protective storage, and digitisation to rescue the fragile collections they have already inherited.

What do you think? If your library could only invest in one approach, would you prioritise advocating for acid-free paper to protect future collections, or pour resources into rescuing the brittle books already on your shelves? And how would you decide which fragile items are worth saving when you cannot save them all?

References

1. https://www.nedcc.org/preservation101/session-4/2inherent-vice-materials
2. https://chinapreservationtutorial.library.cornell.edu/content/paper/
3. https://psap.library.illinois.edu/collection-id-guide/paper
4. https://www.iso.org/standard/17562.html
5. https://edu.rsc.org/feature/paper-conservation/2020204.article
6. https://en.wikipedia.org/wiki/Mass_deacidification
7. https://en.wikipedia.org/wiki/William_Barrow_(chemist)
8. https://ask.loc.gov/preservation/faq/337513