Books

Book structure, materials and damage to books

The life-span of books will be determined to a large degree by:

• their structure and their ability to open well in use; and

• the materials from which they are made.

It is important, therefore, to have some information about structure and materials so that you can provide appropriate care.

The book as a structure

All books are three-dimensional structures that are required to move. For this reason they should be strong, flexible and durable. Unfortunately this is not always the case. For example, many modern books, particularly text books and reference books, don't have adequate sewing and binding structures to support the weight of their textblocks. This is made worse when the books are stored upright in shelves. As a result, the textblocks sag and the spines tend to collapse. The sewing also breaks down and the sections within the book begin to come loose.

Some older books bound in the flexible style are very difficult to open fully. The term flexible in this case refers to the spine, which ideally remains flexible and curves when the book is opened allowing the pages to throw open fully. In this style, the covering material, usually leather, is glued tight to the spine of the textblock. Unfortunately, excessive lining and over-enthusiastic use of glue have often led to very inflexible structures. This style of binding is also not suited to textblocks with very stiff paper.

Click here to see diagram

Books are designed to be moving structures, so that they can be opened and read. The evolution of book design did not anticipate the development of flat-bed photocopiers. Many books are being subjected to uses that their structures cannot withstand repeatedly.

Deterioration of materials in books

There are a large range of materials used in book production. They are all in very close contact, and will affect each other. If some of these materials are poor quality and begin to deteriorate, they are highly likely to adversely affect the other materials in the book.

Paper is very vulnerable to damage and deterioration if stored in poor conditions, or if made from poor quality ingredients. Many papers, particularly modern papers, become acidic over time. Often the acids develop in the paper from the breakdown of the materials in the paper. These acids attack the cellulose fibres which make up paper, shortening the fibres and making the paper more brittle.

This paper is a poor-quality paper that contains lignin. The paper has discoloured severely, is brittle and breaks easily. Photograph courtesy of Artlab Australia

Lignin, from untreated wood pulp, breaks down and produces acids when it is exposed to UV radiation. These acids discolour paper and make it brittle.

Some sizing agents break down to produce acids. Sizes are applied to paper to stop inks soaking into it, as they would into blotting paper.

Chlorine bleaches used to whiten paper can remain chemically active in paper for a considerable time. Chlorine can combine with moisture from the air to produce hydrochloric acid.

Impurities in the water used during papermaking can damage paper. Copper and iron are particularly damaging.

Paper is a food source for insects, rodents and moulds.

Insect damage can be extreme as seen on this severely damaged book. Photograph courtesy of Artlab Australia, reproduced with permission of the State Library of South Australia

Boards on hardcover books, and the thin cardboard covers on paperbacks, are made in a similar way to paper and they often have many of the same problems as paper. They can become acidic and these acids can migrate into the textblock.

Strawboard is an exception. Lime is used in its manufacture, so the board is quite alkaline. It

has a distinctive, brown-yellow colour which when wet readily stains anything it contacts. This stain can often be mistaken for discolouration caused by acids.

The interaction of adhesives, covering materials and boards in conditions where relative humidity fluctuates can cause severe distortion of the boards. This leaves the textblock vulnerable to damage.

Some inks and pigments can damage paper. For example:

• iron gall inks—which were used extensively for manuscripts—contain acids and iron, which both attack paper;

• verdigris—basic copper acetate—was used in many Islamic books, particularly in borders around text. In many cases, this pigment has eaten into the paper; and the text it surrounded can easily drop out.

The acids from the iron gall ink on these pages have attacked the paper, leaving it very brittle. The paper is also very discoloured. Photograph courtesy of State Library of New South Wales

The green border around the text has been painted with verdigris—a copper pigment. The damage you see in this photograph is very typical of older Islamic books where verdigris is used extensively as a border. Photograph courtesy of Artlab Australia, reproduced with permission of the State Library of South Australia

Many inks and pigments are affected by UV radiation, high lighting levels and extremes of temperature and relative humidity; this results in inks fading and discolouring, and sometimes becoming blurry.

Animal glue is essentially a poor-quality, impure gelatine. It is a rich food source for insects and moulds—cockroaches enjoy a good munch on animal glue. Animal glue breaks down when it ages. It often becomes discoloured and darkens, which can cause staining. It can also become very brittle. When this happens, it crumbles and falls away.

The animal glue around the left and lower edge of this watercolour is very discoloured, and on the left hand edge it has become brittle and broken up. Photograph courtesy of Artlab Australia

This vellum page from a 13th century manuscript shows extensive cockling. Photograph courtesy of the State Library of New South Wales

Vellum and parchment are untanned animal skins. They are both very moisture-sensitive. In high relative humidity conditions the skins absorb moisture and can distort and cockle. As the relative humidity decreases, the skins dry and become less flexible, and distortions and creases can become set into the skin.

Vellum and parchment can be attacked by insects and mould. Unlike paper—because lime is used in their manufacture—they are not susceptible to attack by acids.

The leathers traditionally used for bookbinding are vegetable tanned leathers and are very susceptible to:

• insect and mould attack;

• fading when exposed to light and UV radiation;

• drying out and losing their flexibility; and

• red rot. Leathers with red rot have a rusty-red colour, and leave fine deposits of red powder on shelves, tables and hands. When the chemicals in leather start to breakdown, the leather becomes powdery. Sulphur dioxide—a common atmospheric pollutant—combines with moisture from the atmosphere to form sulphuric acid, which breaks down the leather fibres. The leather loses its flexibility, splits and crumbles forming a fine red powder.

This leather binding has deteriorated under the action of sulphur dioxide pollutants in the atmosphere. This leather has a condition called 'red-rot'. Photograph courtesy of Artlab Australia reproduced with permission of the History Trust of South Australia

Many bookcloths are susceptible to damage from mould and insect attack, and to fading caused by excessive light levels and exposure to UV radiation.

Examine your collection. How many books have faded spines, yet the front and back covers are closer to their original colours because they have been protected by the other books on the shelves? Many bookcloths can also be discoloured and damaged by water.

The lighter areas on this bookcloth are areas of water damage. Photograph courtesy of Vicki Humphrey