Volume 1, Number 1
Jun 1994

Paper Permanence Debate Lends Drama to Paris Conference

The Association for Scientific Research in the Graphic Arts (Association pour la recherche scientifique sur les arts graphiques, or ARSAG) held its second international conference in Paris, May 16-20. It was called "Environnement et Conservation de l'Écrit, de l'Image et du Son" (Environment and Conservation of Written Records, Images and Sound), and it included a feature unusual for a conservation conference: nine (9) presentations on the permanence of paper:

1. "The effects of air pollutants on accelerated ageing of cellulose-containing materials: Preliminary results of the STEP paper project CT90-0100," by J.B. Havermans
2. "Permanence of paper in light of six centuries of papermaking in Europe," by K.B. Hendriks
3. "Present state of recycling technology in papermaking in Europe," by D.J. Priest
4. "The ageing of bleached kraft pulp," by T. Iversen
5. "Stabilité au vieillissement artificiel des papiers contenant des pâtes à haut rendement (Stability during artificial aging of paper made from high-yield pulp)," by F.A. Abadie-Maumert
6. "The ageing of paper containing chemithermomechanical pulp," by D.J. Priest and J. Stanley
7. "The role of lignin in the mechanical permanence of paper," by X. Zou
8. "Le papier permanent: Quelle offre, quelle demand? (Permanent paper: What is available, and what is the demand for it?)," by M. Walckiers
9. "Quel coût de papier pour quelle permanence? (How much permanence do you get for your money?)," by B. de Montgolfier.

A few excerpts from the papers and the discussions that followed the papers can be given here. The excerpts should not be taken as exact quotes of anyone, although pains were taken to record the discussions as fully and accurately as possible, knowing that they were not recorded elsewhere. (It should be noted that we did have simultaneous translation from French to English and vice versa.)

The lignin issue. Havermans reported that the massive STEP project is nearly finished. It involved a variety of papers: old and new, acid and alkaline, lignin-containing and freesheet, and deacidified and non-deacidified. They were aged with and without pollutants and tested before and after. The acid and lignin-containing papers aged similarly, he said. Someone asked what the pH of the lignin-containing paper was, and he said slightly acid, but even when they had been deacidified they behaved the same.

Zou, in his paper, said that washing lignin-containing pulp in tap water conferred the same resistance to aging as sodium hydroxide or calcium carbonate filler, because metal ions in the water neutralized the acid groups in the hydrogen form. All the aging was done at one temperature (80°C) and relative humidity (75%), in sealed glass bottles.

Abadie-Maumert reported research in which BCTMP and bleached kraft pulp were aged at 80°C and 65% RH for 150 days. After the first 100 days, the pH of both types of pulp stabilized near 5.0, having fallen from around 6.0.

Accelerated aging and the process of deterioration. A session chairman observed that four different speakers had reported using four different aging conditions that morning. He made a fairly mild comment to the effect that "research should be to some extent comparable." A moment later someone (a scientist) objected, saying that not everything could be standardized as the chairman wanted.

Klaus Hendriks' presentation differed in part from the paper in the preprints, but both versions were insightful and thought-provoking. He described three kinds of properties that change during aging: physical, chemical and optical. He said that chemical changes may or may not cause mechanical and optical properties to change, so they cannot always be detected by measuring mechanical properties. He showed slides demonstrating that a chemical property (degree of polymerization) can change quite a lot before physical properties begin to change. In the discussion period, someone asked how that could be so, and asked for evidence. Hendriks said we have to decide which we want to test for: retention of strength or chemical changes. They do not often vary together, but one type of change may be 100 or 200 years ahead of the other.

Hendriks also made the point that accelerated aging conditions can have a very large effect on results. He did not mean temperature and relative humidity, necessarily, but such apparently trivial matters as whether the paper sample was aged hanging freely in the chamber, or in a pile with other papers. We now know that paper ages much faster in a pile or enclosure.

Several speakers made the point that we have to learn more about accelerated aging.

Performance-based standards vs. content standards. In reply to someone's comment about the user's right to know the chemical composition of papers, Hendriks said that in other areas of life you usually want to know what material your purchase is made of. If you want to buy a certain shirt, for instance, imagine learning that no one will tell you whether it is polyester. The clerk, however, is certain it is the right shirt for you. This is the situation we would have with paper if we adopt performance-based standards.

Nuclear induction of electromagnetism. One speaker described the threat to all our magnetic records posed by a high altitude (over 30 km) nuclear explosion, which would generate gamma radiation and erase all magnetic records within a wide area that had not been "hardened." In the discussion period, someone asked who would be alive then to save our heritage. The speaker said that the atmosphere protects us; only the electromagnetic radiation gets through; and had he understood the question correctly? The person replied, "Yes--You're promoting the use of paper."