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Dr Phillipp Stolper

Dr Philipp Stolper

Materials & Environment

transparent 11x15@fogra.org

+49 89. 431 82 - 354


Ageing resistance of paper (according to ISO 9706)

Prints to be archieved indefinitely for legal, cultural or other reasons need to be produced from specially selected materials to ensure readability and usability for very long periods of time.

In the past acid containing substances within the paper caused large problems with respect to the mechanical strength of prints or written matter. Such damaged materials may only be restored by huge efforts. Reason for the paper degradation was the acid-catalysed decomposition of cellusosic fibres that give the paper its strength.

Therefore ISO TC 46 “Information and Documentation” prepared a list of criteria aiming to ensure unlimited archiving of papers.

The criteria are:

  • Testing the mechanical strength of the paper by evaluating its tearing strength according to the method of Elmendorf (ISO 1974)
  • Determination of the alkaline capacity of the paper (ISO 10716)
  • Testing of the oxidation resistance of the paper (modified Kappa number according to ISO 302)
  • Determination of the pH-value of the cold water extract of the paper

Meeting all criteria simultaneously ensures a minimum tear resistance, a minimum amount of acid containing substances, a minimum amount of easily oxidisable substances and an optimized pH value. Based on such requirements an unlimited usability of the paper, written documents and prints is most likely.

Fogra performes tests according to these requirements and approves products that comply with the test criteria. Manufacturers and users of such papers are encouraged to use the conformity symbol of ISO 9706 for their products.