Some papers are described as permanent or long life, and may include the infinity symbol in the advertising literature. However, paper is organic, biodegradable cellulose fibres derived from plant matter, which effectively contradicts the notion of permanence. Therefore, it needs to be understood that the life expectancy will depend on the source and quality of the fibre as well as the chemicals applied during pulp and paper production. The subsequent processes of printing and storage will also be crucial to the rate of subsequent degradation.
There are papers which are made to conform with the “long life” International Standard ISO 9706, but this may not be sufficient for some applications. There are some serious dangers regarding ISO 9706 which require amplification. It is well known from the horror stories of BS5750 that a Standard is only as good as the precise definition of the standard. If the standard is set at a low level, then products or services can, in some circumstances, prove very disappointing.
ISO 9706 is certainly perfectly adequate for compliance with the practical aspects of the Statute of Limitations (6 years). There are, however, many applications, such as Fine Art reproduction or information which will be required by future generations, when a considerably higher standard is required. This problem is best set out by quoting from ISO 9706 itself:
Optical Properties “This international standard does not include tests to ensure retention of optical properties, such as brightness, Y value, gloss or fluorescence. The reason for this is that in the uses envisaged for the papers, some loss of brightness or slight yellowing is less important than retention of mechanical strength; a certain degree of discolouration can be tolerated before most printed material becomes illegible. It was therefore considered that the added complication of specifying optical tests was unnecessary, especially as accelerated ageing tests would almost certainly be needed, including exposure to light.”
Bearing in mind that the British Trade Standard definition for the paper trade of an uncoated woodfree and acid free paper can include 10% Thermo-Chemi-Mechanical Pulp and 1% lignin, it is clear that British Standards are not always what one might expect. The lignin produces acids as it degrades, thereby introducing a destructive force into the paper.
There are even some papers being sold for Artist use which include recycled fibre and are described as “acid free”. Clearly, even if a paper contains “best white waste”, it cannot be guaranteed not to contain any mechanical pulp, and the resulting lignin. Close questioning of the manufacturer reveals that the term acid free is used because they do not add any acids during the production process and add some Calcium Carbonate buffering. Unfortunately for the artist, this does not help the uncertainty about purity of the pulp.