Paper corrosion - Challenge in archives and libraries
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Paper corrosion or paper decay is the dissolution of paper due to ageing, which is often triggered by the effect of acids present in the material and can be accelerated by external influences.
Paper decay or paper corrosion is the dissolution of paper due to ageing, which is often triggered by the effect of acids present in the material and can be accelerated by external influences.
Today, paper gets its structural stability from the use of cellulose fibres made from pulp.
In order to prevent the writing from leaking, paper was impregnated from the beginning of the 19th century by mixing resin with alum. However, if the paper is stored for a longer period of time, this low pH value leads to a destruction of the cellulose chains, so that the fibre composite of the paper disintegrates. However, since the vast majority of paper products, such as newspapers, do not need to have a long shelf life, this was not considered an important problem.
Nowadays, other flocculation systems exist that allow the use of calcium carbonate as a filler. They form an alkaline reserve in the paper that prevents acetal cleavage of the cellulose chains by acidic paper ingredients.
Another factor that can accelerate paper decay is wire stapling, which contributes to the destruction of the adjacent paper in the fold area in case of rusting.
External influences for paper decay are mainly moisture, which enables the development of pests, heat, which accelerates the ageing of the paper as well as all other chemical reactions, and light.
Air pollutants such as formaldehyde, sulphur oxides, nitrogen oxides or ozone can also accelerate paper decay. Other factors that promote paper decay are the use of Post-Its and adhesive tape.
Treating paper decay
In addition to insect infestation, for example by bookworms or silverfish, ink erosion and mould, acid-related paper decay is one of the greatest challenges for preservation in archives and libraries. There are various methods to stop the decay, by means of deacidification or permanently by paper splitting. Paper damaged by moisture can be treated by freeze-drying.
Ageing resistant paper
Ageing resistant paper is paper that contains few or no ingredients that accelerate its ageing. Requirements for ageing-resistant paper are defined in DIN EN ISO 9706, among others.
