Consultancy Agency and Workshop for Preservation, Conservation and Restoration of Books,
Archival Materials and Graphic Arts. Preservation Management for Libraries and Archives.
Diploma HICOREB. Accredited Conservator Restorer. Member of the Institute of Paper Conservation.
Deterioration
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Deterioration. Nature has developed splendid and ingenious mechanisms to recycle about everything on earth. This is of course very good since without recycling humanity would be buried under its own waste. However nature does not make any distinction between the things we want to keep and the things we want to get rid off. So to make sure we can keep what we want, we have to take positive action, called preservation. Preservation measures are specific to the objects we want to keep and to the kind of threat these objects are subjected to. So to be able to respond to these threats in an adequate way, it is necessary to know as much as possible about them. Two important chemical reactions play an important role in deterioration, i.e. oxidation and hydrolysis.
Oxidation is a chemical reaction in which oxygen is assimilated, hydrogen is released or, more generally electrons are released out of an atom. This reaction occurs in the presence of an oxidizing agent. Mostly this oxidizing agent is oxygen, although this is not always the case. The most naturally occurring source of oxygen is the oxygen in air. The oxidation process, which happens by means of oxygen in the air, is nothing else than a natural combustion. It goes very slow for most substances, but can be accelerated considerably by so-called catalysts and heat. Degradation by oxidation is also induced by using oxidizing bleaching components and their residues
Hydrolysis is a chemical process in which molecules can be divided under influence of water, due to its polarity. It splits weakly in H3O+ and OH- ions. The concentration of these ions is the same. The chemical balance implicates an ion concentration of 10-7. When one adds acids to water, the H+ concentration rises and an excess of H+ ions is available. A strong acid splits up completely in ions, which makes the increase in H+ ions very large. A weak acid splits only very limited in ions, which makes the increase in H+ ions equally rather small. These H+ ions catalyze the hydrolysis reaction. The greater the concentration of these ions, the quicker the reaction occurs. This is called acidic hydrolysis. The reaction finally results in breaking up basic components of library and archive materials. Hydrolysis is being catalyzed by agents as lignin, iron gall inks, chemicals, atmospheric pollution, relative humidity and others Although deterioration is a complex process that involves different kinds of agents, which can reinforce the influence of one another, we distinguish following categories of threats
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