Paper and books

A large part of the paper in most collections is chemically unstable and was unstable from the day it was made. Understanding which part, and why, decides where the effort goes.

The acid problem

Paper made before the mid-nineteenth century was generally produced from cotton and linen rag, sized with gelatine, and is frequently in good condition today. Paper made after the shift to mechanical wood pulp contains lignin and was often sized with alum, and the resulting acidity hydrolyses the cellulose. The chains shorten, the sheet loses strength, and the process generates further acid as it goes, so it accelerates.

This is why a nineteenth-century newspaper can be more fragile than a fifteenth-century book. It is not a matter of age but of manufacture.

The environmental levers on this are real but modest. Lower temperature slows the reaction meaningfully. Lower humidity slows hydrolysis, though not to the point where very dry storage becomes advisable, since brittle paper handles worse. Acid migration from neighbouring material can be prevented, which is where enclosure choice earns its keep.

Deacidification neutralises the acid present and deposits an alkaline reserve against future acid formation. It stops the mechanism from continuing; it does not restore strength that has already been lost, and it is contraindicated for certain media. It is a conservation treatment, not an environmental measure.

Iron gall ink

Iron gall ink was the standard writing ink in Europe for centuries and it attacks the paper it sits on. Excess iron catalyses oxidative degradation of the cellulose, and the ink lines themselves become brittle, crack and eventually fall out, leaving the writing as a set of holes in the shape of the words.

Documents with iron gall ink need identifying and separating, because their requirements differ. They are particularly sensitive to high humidity, which accelerates the reaction, and they must not be treated as ordinary manuscript material. Where this is suspected, specialist advice comes before any handling decision.

Enclosures

Paper is a plant fibre and generally benefits from a buffered enclosure: the alkaline reserve absorbs acid as it forms and slows the degradation.

The exceptions are important. Do not use buffered material for photographic prints and negatives, for some dyes and colourants, or where the enclosure will also hold protein material such as parchment or leather bindings. Where a collection is mixed and sorting is impractical, unbuffered neutral material throughout is the safe compromise.

For plastic enclosures, polyester, polyethylene and polypropylene only. PVC sleeves plasticise and release acidic degradation products, and they are still widely sold. Acid-free boxes and tissue covers the full specification.

Books as objects

A book is a mechanism, not a stack of paper. Boards, spine, sewing and covering material all move differently and all bear load.

Shelve upright with neighbours on both sides providing support, and never leaning, because a leaning book is being permanently deformed under its own weight. Shelve oversized volumes flat, no more than two or three high. Fore-edge shelving, resting a book on its front edge, pulls the text block away from the spine and should not be used.

Support the opening angle when a book is consulted: a foam cradle or a book pillow prevents the spine being forced flat, which is the most common cause of damage in reading rooms. Weighted snakes hold pages open without a hand pressing on them.

Light and display

Paper and its media are in the more responsive categories, and works on paper are among the material most often damaged by well-intentioned permanent display.

The controls are the same as for textiles: filter the UV, keep illuminance low, and above all limit hours. A budget with a running total per object is the mechanism that makes rotation enforceable rather than aspirational.

Climate and pests

Sustained damp brings mould, and paper is a good substrate for it. It also brings silverfish and booklice, both of which graze surface sizing and coatings and both of which are, first and foremost, a signal that the space is too humid.

A cool, moderately dry, stable store with sealed enclosures addresses all of this at once, and does so more cheaply than any single intervention aimed at one agent.