Literature

"The Aging Characteristics of European Handmade Papers: 1400-1800," by John F. Waterhouse and Timothy D. Barrett. Tappi Journal, Oct. 1991, p. 207-212. Nondestructive or nearly nondestructive test methods were used to analyze a number of early papers, presumably chosen from the same group of 560 papers that Barrett gathered for his 1984-87 research, reported in the 1989 Paper Conservator (v. 13, entire volume). Then as now, two experimental groups of papers were chosen for investigation, those in good and poor condition as determined by ordinary handling and examination, regardless of whether their condition was due to manufacture or storage conditions, which of course can only be guessed at; and nondestructive methods were used as much as possible, for the obvious purpose of extending the life of these scarce specimens. More sophisticated testing was done for this study than earlier, including use of fourier transform infrared reflectance spectroscopy to determine gelatin content (good paper had three times as much, and the gelatin in poor papers was in a degraded state). Elastic constants were measured by ultrasound and found to be at least twice as high for the good papers; elasticity was correlated with amount of gelatin present. The good papers were alkaline and the poor papers were acid. An unexpected finding was that the good papers had shorter, though not necessarily stronger, fibers.

The purpose of the study was simply to determine the factors responsible for the differences between the good and bad papers in this naturally aged group of papers. Much of this report is taken up with results from Barrett's work reported earlier in the 1989 Paper Conservator, which is referred to in the bibliography as "1. Inst. Paper Conservation.'

"A Study of the Effects of Iron and Copper on the Degradation of Paper and Evaluation of Different Conservation Treatments," by Henk Porck and W. Castelijns. A paper given at the August 1991 meeting in Uppsala of IADA (the German-speaking association of book and paper conservators). The first author's address is: Conservation Department, Royal Library, P.O. Box 90407, 2509 LK The Hague, The Netherlands.

They were able to protect paper against further damage from iron and copper compounds (the troublemakers in iron gall inks and in certain pigments used for illuminated manuscripts) by treating them with both magnesium bicarbonate and ammonium caseinate (an uncommon adhesive which is used in the Rotterdam Municipal Archives and which binds acids and metals). Aging was done at 90°C and RH cycling between 35% and 90%. EDTA, a metal chelating agent some times recommended in paper conservation, was worse than nothing because it deteriorated the paper instead of protecting it. (From the February Abbey Newsletter)

"The Use of Recycled Papers in Records." A 4-page leaflet issued June 1991 by the Australian Archives. It provides some background information on papermaking and recycling, and weighs the quality, cost and utility of recycled paper used for records. Recycled paper and paper products which include recycled fiber, it says, should not be used for:

Records to be kept for more than ten years
Records used or handled frequently, e.g., plans, maps
Publications needed for long term reference
Documents provided by government or other authorities including birth and citizenship certificates, legal documents, title deeds, etc.

For more information contact the National Director, Storage & Preservation, Australian Archives, PO Box 34, Dickson, ACT 2602 (Fax 011-61-6 2433 693).

"A Rapid Method for Measuring Yield in Semichemical Pulping Processes," by Pawel Wandelt and Wladyslaw Mroz. Tappi Journal, March 1992, p. 203-205. A method of measuring pulp density is described, for calculating the yield for pulps produced by certain new NSSC (neutral sulphite semichemical) processes. The kappa number does not work for them: they show no correlation between yield and kappa number. The method involves drying balls of pulp and putting them into mixtures of carbon tetrachloride and chloroform, then heating the mixture and noting the temperature at which they start to sink.

"The Microporosity of Pulp: The Precipitation of Inorganic Fillers Within the Micropores of the Cell Wall," by G. Graham Allan et al. Tappi Journal, January 1991, p. 175-178. A closely related paper by some of the same authors (G. Graham Allan, Alberto R. Negri, and Philippe Ritzenthaler), entitled "The Microporosity of Pulp: The Properties of Paper Made from Pulp Fibers Internally Filled with Calcium Carbonate," appeared in the March issue on p. 239-244, with a note saying that telephone inquiries should be directed to Prof. Allan at 206/543-1491 (office), 206/486-1649 (home) or 206/685-3091 (fax).

These two papers describe a method for forming precipitated mineral fillers such as calcium carbonate within the cell wars of never-dried pulp fibers by bathing them first in one salt solution and, after washing off the excess, in another salt solution that reacts with it. The unreacted salt is then washed off, leaving the outside of the fiber free to bond with other fibers, accept dyes and pigments, and so on. Upon drying, the pores in the cells close forever, locking the precipitate in. Very high filler loadings can be achieved this way, without the usual problems of filler retention and strength loss.

An earlier process of adding filler by precipitation was introduced in the 1950s, and has been improved since then. It has seen use most recently for the controlled release of medicines and agricultural chemicals.

The principle is the same as the "double decomposition" method of aqueous deacidification developed in the early 1970s by John Williams, George Kelly and Richard L. Best at the Library of Congress (U.S. Patent # 3,898,356), except that the precipitate for the double decomposition method forms within the pores of the paper rather than the fiber. This method has been used rarely if at all in conservation.

Paper Chemistry, edited by J.C. Roberts. Published in the US by Chapman and Hall, a division of Routledge, Chapman and Hall, Inc., 29 West 35th St., New York, NY 10001-2291 (212/244-3336); in the UK, by Blackie & Son, in Glasgow and London. 1991. 234 pp. $127.50 US; $159.50 Can. Available only in cloth.

The first question that comes to mind is whether such a small book is worth the price. Answer: yes. It is on a par with Clark's Pulp Technology and Treatment for Paper, though not nearly so long. The 12 chapter topics are well chosen and the contributors, experts from five countries, developed them well. They are C.O. Au, R. Bown, N. Dunlop-Jones, J.M. Gess, D. Hon T. Lindström, F. Linhart, J. Marton, S.G. Murray, F. Onabe, G.A.F. Roberts, and J.C. Roberts. Among the topics they cover are applications of paper chemistry, accessibility of cellulose, retention aids, dry-strength additives, neutral and alkaline sizing, dyes and fluorescent whitening agents, and fillers.

The editing is considerate and careful. The chapter on neutral and alkaline sizing, like the other chapters, is technical but clear and logical, and covers the main points better than anything published so far. The references cited include both up-to-date and much older literature as well as material from the last decade or two. The four-page index, however, is too short for such a fact-packed book.

Paper Chemistry---An Introduction, by Dan Eklund and Tom Lindström. Publisher: OY DT Paper Science Ab, Mariantie 9, SF-02700 Kauniainen, Finland. A revised translation of a Swedish edition published in 1990. $95 cloth, $85 softcover.

"The Effect of Microwave Drying on Paper Properties," by Pawan Kumar, Arun S. Mujumdar and Zoltan Koran. Paper presented at the 76th Annual Meeting of the Technical Section, Canadian Pulp and Paper Association, 1990, Montreal. Preprints "B," p. 161-166.

Kraft and CTMP pulps, refined to three different levels, were dried by three methods and the physical properties of the handsheets compared. The fastest drying rate was found to be 2450 MHz. Microwave drying produces lower (125°C) and more uniform temperatures in paper, and is more efficient than infrared drying though at present it costs more. It could be used to advantage in combination with existing equipment.

The effect on double fold is to increase it 10%-60%, but other physical characteristics were about the same as those of paper dried by the usual methods.

Conservators in France and Germany, but not the U.S., have used microwave drying for paper after wet treatments and in salvage operations after floods.