3: Paper

Paper is made from cellulose fibres which can be derived from many kinds of plants. Huge amounts of paper have been manufactured and very large amounts of paper can be found in public collections. Paper is present in everyday life in many forms with surfaces embellished with writing or decorative features. The basic principles behind the formation of paper will be discussed as well as the common additives. The stability of well-stored paper can be decreased by two chemical mechanisms, acid-catalysed hydrolysis and oxidation. The causes for the acceleration of decay by these mechanisms are reviewed as well as the various conservation processes and storage conditions which can be used to slow down degradation. Paper often discolours on ageing and although some of the ageing products can be removed with water, bleaching can be used to restore the original hue. Paper interacts with water causing chemical and physical changes, some of which are of vital importance to the proper care and conservation of the paper. There are many analytical techniques that can be used on paper ranging from very simple “spot” tests to those involving large instrumental systems; the most useful of each kind are described. Methods of testing the strength of paper are also very useful. A case study of a research project on the washing of paper is given to illustrate how basic information on the properties of discoloured paper has been obtained.