The chemistry of paper conservation

Abstract

There are probably more collectable objects based on paper than any other material: books, prints. drawings, watercolours, stamps. banknotes, matchbox labels etc. Not surprisingly, owners of such objects want them to remain in good condition despite the fact that many of them were only intended to have a lifetime of as little as a few hours. e.g. tickets. However, some papers and the images upon them are inherently unstable and others deteriorate quickly when stored under the wrong conditions.The study of paper conservation can be split into four areas: ( i ) the chemistry of the deterioration of paper and the writing or images thereupon. (ii) the physics and chemistry of processes that can be performed to enhance stability and appearance, (iii) the practical skills needed to carry out active conservation processes, e.8. bleaching and Fvashing, and (iv) the management and storage of a collection. This review will concentrate on the first two of these areas as these \i ill be of more interest to chemists.There are two ways in which paper objects can be prevented from deteriorating; these are sometimes known as passive and active methods. Passive methods are those which involve creating good storage and climatic control so that damage by handling, incident light. thermal degradation. air pollution and excessively high or low relative humidity is minimised. Active methods involve treating objects to clean and stabilise them: examples of this are washing, deacidification and repair.

Deacidification of Acidic Books and Paper by Means of Non-aqueous Dispersions of Alkaline Particles: A Review Focusing on Completeness of the Reaction

“…Ozone coming from electrical equipment is a likely source of such oxidation in libraries (Andretta et al 2016). Daniels (1996) showed that such effects can be accelerated by the presence of iron and copper in paper. Whitmore and Bogaard (1995) and Stephens et al (2009) showed that oxidation tends to make the paper more susceptible to mechanical breakdown during subsequent acid hydrolysis.…”

“…It is well known that paper documents can be adversely affected by airborne oxidants such as ozone and nitrogen oxides (Arney et al 1979;Daniels 1996;Bogaard and Whitmore 2001;Stephens et al 2009). In fact, such oxidation appears to make the paper more susceptible to acid-catalyzed hydrolysis in some cases (Whitmore and Bogaard 1995;Stephens et al 2009).…”

“…One such criterion involves the pH of the paper (ANSI 1984;Daniels 1996;Ramin et al 2009), a quantity that can be determined either by placing a drop of water on the paper surface (TAPPI Method T529), or by extracting the paper with aqueous solution (TAPPI Methods T435, T509; ISO 6588 2012), or possibly by redispersing some of the paper in water and then measuring the pH. Since all such measures involve liquid water, ordinary pH tests cannot answer the question as to whether a given deacidification treatment had already brought about neutralization of acidic sites within the paper prior to the test itself or whether such neutralization became completed only at the time of pH testing.…”

Influence of Bleaching Materials on Mechanical and Morphological Properties for Paper Conservation

“…The paper degrades naturally throughout three main reactions: acid-catalyzed hydrolysis of cellulose molecules, oxidative degradation induced from atmospheric oxygen and light, and thermal degradation that leads to chemical bond breakage as the temperature is increased. Artificial paper aging tests have demonstrated that these reactions become more intense when temperature is incremented [3]. Yellowing caused by aging, foxing that can appear due to iron oxidation or because of the presence of microorganisms [4,5].…”

Toner-print removal from paper by long and ultrashort pulsed lasers

“…It is known (Daniels 1996) that paper degrades naturally through three main reactions: acid-catalysed hydrolysis of cellulose molecules, oxidative degradation induced from atmospheric oxygen and light, and thermal degradation that leads to chemical bond breakage as the temperature is increased. Artificial paper ageing tests have demonstrated that these reactions become more intense if temperature is incremented.…”