Books have the same enemies as people: fire, animals, weather and their own content
Paul Valérie (1871-1945)

Paper

Paper was and still is the most common information carrier. Today millions of books and documents are being threatened by acidification and embrittlement. This problem has manifested itself primarily in relatively recent material, dating from the last 150 years. To understand this problem we have to explain a little bit about the process of papermaking.

Papermaking

Until the end of the 18th century papers were handmade and made of cotton or linen rags. The main component of this material is pure cellulose. The fibers were beaten in a stamping mill, retaining much of their length, and no additives were used that had a deteriorative effect. Paper from this period, stored under good conditions, is generally still quite strong and flexible.

The growing demand of paper led to a greater mechanisation, and processess and materials were introduced that produced a much poorer quality paper. Because of the shortage of rags, other papermaking materials were sought that would be both plentiful and cheap. By the second half of the 19th century wood became the main raw material for papermaking. But before wood can be made into paper, it has to be turned into woodpulp. This can be done in two ways: mechanical and chemical. Experiments with the first method, began in the 1840s. Wood chips are mechanically ground to pulp, and paper made of this "ground" or "untreated" wood" (the pulp retains all of the components of wood except for the water-soluble materials) is cheap but of a very bad quality. Nowadays it is only used for very cheap paper such as newspapers.

Shortly after its intoduction it became clear that groundwood paper quickly deteriorated. New methods were sought to obtain a strong high-quality paper from wood. Chemical wood pulp is made by cooking wood chips at high temperature in various chemical solutions to remove as much non-cellulosic material as possible. The fibers remain longer which contributes much to the strenght and durability of the paper.

Paper Enemies

The permanence of paper is influenced by the way it is manufactured, and the way it is used and stored. The main cause for concern is acidification: paper turns brownish yellow, the fibres break and eventually crumbles into dust.
Acidification is caused by chemical treatments to improve the wood pulp and by various additives used for bleaching, sizing (makes paper less absorbent and more suitable for writing) filling and coating. Bad storage conditions like fluctuating temperatures, high humidity, atmospheric pollutants such as dust and an excessive amount of light can speed up the proces. Also some traditional writing inks were highly acidic.
Other threats are biodegradation from insects and mould and of course bad handling.

Deacidification

Deacidification, i.e. the neutralisation of acids, is considered the best way of overcoming paper degradation. Deacidification can increase the life of paper by a factor 3 to 5. Initially deacidification processes were designed to treat documents individually, but the vast amount of library and archive materials that need treatment made the development of mass processes necessary. Many books and documents however, especially from 1840-1950, are so brittle that mass deacification is no longer useful, only transfer to an alternative medium can save the contents.
The principle of acidification will be explained by means of cartoons made by Henk Porck, conservation scientist of the National Library of the Netherlands and author of Mass deacidification. An update of possibilities and limitations, published by the Commission on Preservation and Access and the European Commission on Preservation and Access.

Permanent Paper

Permanent paper is paper which meets the specifications of standards designed to ensure it will remain stable over long periods of time. This means that it will not discolour or become brittle with normal usage, such as examination and copying. Librarians and archivists have been campaigning for standards for paper manufacture and legislation to enforce its usage for all publications of long-lasting interest. To preserve our documentary heritage it is important that the use of permanent paper increases. Acid-free permanent paper is no more costly than acid paper and is environmentally sound because alkaline paper mills produce less pollution and permanent paper is recyclable and biodegradable. Some countries have developed their own standard, but a universal standard issued by the International Organization for Standardization (ISO) is now available: ISO 9706:1994.
Publications on papers meeting the ISO 9706 specifications can be recognized by this sign,
or by a statement.

This paper meets the requirements of ISO 9706:1994, Information and documentation - Paper for documents - Requirements for permanence.

The following pages offer an overview of frequent types of damages, encountered in archives and libraries.