Literature

"Chemical and Physical Condition of Paper in Archives and Libraries," by P. Zeisler, U. Hamm and L. Gottsching. Papier 47 #2, Feb. 1993, p. 62-67, 69-73 (in German). Ref. from Paper & Board Abstracts (PBA) 1993, abstr. #3178. Paper in 265 samples from the last 290 years at three locations in the state of Hessen was analyzed for strength and fiber composition. Up to 18% of the documents are considered fragile. (1A1)

"Business Image Abrasion Testing: Committee F-5 Measures Image Adhesion to Receptor Media," by William D. Glover. ASTM Standardization News, Oct. 1993, p. 66-68. ASTM's Committee F-5 concerns itself with business machines that make original documents every time (mailing labels, correspondence, and "the effluent of copy machines"), and with the supplies such as paper and ink that are used in those machines. Impact printing systems (typewriters, dot-matrix printers) leave an image that is almost always permanent, but they are less popular than they used to be. Nonimpact printing images may lack permanence because of the chemical composition of the ink or the adhesion of the printed image to the receptor media (usually paper). The three main kinds of nonimpact printers are ink jet, electrophotographic and thermal. Ink jet is used for lot coding of drug capsules, for example; electrophotographic printing is used in laser printers; and thermal printing is done in fax machines and bar code printers.

Adhesion or degree of fixing of a printed image is hard to measure. The committee decided in 1991 not to use any of four existing abrasion test methods, because they were designed for other purposes or conditions. Instead they wrote separate test methods for each of the four machines, and gave the tester a choice of which one to use. The procedures will soon be published in the Annual Book of ASTM Standards, Vol. 15.09, under the F-5 section, "Business Imaging Products." (3A9.3)

pHydrion Test Papers and Products, catalog of Micro Essential Laboratory, Inc., 4224 Avenue H, Brooklyn, NY 11210 (718/ 338-3618; fax 692-4491). This 43-page catalog for 1992-93 contains nothing but papers, buffer salts, kits and pH pencils for testing the pH of paper. The company does not advertise, but sells through distributors, who are not listed in the catalog. An interesting new product is the Hydrion pH Indicating Paint, which is applied to a surface where acidic or alkali fumes, spray or fallout are suspected. It changes color on exposure, and can be compared to the color chart that comes with the container to estimate the pH value of the airborne agent, it says on p. 35. (3A9.7)

"Humidity Cycling Rates: How they Influence Container Life Spans," by Craig H. Leake and Robert Wojcik. Tappi Journal, Oct. 1993, p. 26-30. Corrugated boxes are often stored in uncontrolled environments, where alternating extremes of temperature and humidity accelerate their deterioration, yet they must remain strong enough not to collapse even when stacked high or filled with heavy contents. This study investigated whether the rate of temperature and RH cycling influenced box performance, and if so, what rate was most detrimental. They found that rapid cycles (two per day) had less effect on the life spans than longer spans (one cycle every two days) because what mattered was the variation in moisture content. Over the longer cycles, there was a greater change in moisture content of the boxes, which lasted only a fraction of the time that boxes did under constant conditions. Height of the box under a dead weight was used as a measure of deterioration. (3B1.21)

"Effect of Pulp Oxidation on Paper Binding System," by V. Luzakova and T. Marcincinova. Cellul. Chem. Technol. 26 #4, July-Aug. 1992, p. 471-477. Oxidative bleaching introduces reactive carbonyl and carboxyl groups into the cellulose molecule, which affect reactions with other components of the stock. This paper reports the effect of hot-diluted alkali on the bonding system. It increased interfiber bonding but decreases polymerization. (3B1.21)

"Evaluation of Paper Products: With Special Reference to Use with Photographic Materials," by Helen D. Burgess and Carolyn G. Leckie. Topics in Photographic Conservation, vol. 4, 1991, p. 96-105. This is not only a guide to selection of papers and boards for storing photographic materials, but a clear exposition of methods for identifying permanent paper and board in general, with background passages on the rationale of testing and accelerated aging. The reason for specifying very low levels of lignin in paper products to be used with photographs (0.1 to 0.3%) is that photographs are so sensitive to it: lignin gives off peroxides and tends to carry with it both chemically reactive sulphur from the pulping process and chlorine compounds from bleaching.

The authors draw attention to the fact that unbuffered rag board does not qualify as permanent by the ANSI standard for paper permanence. This is mentioned to illustrate the principle that standards should not be used for purposes they are not intended. They give two pages of practical advice (with a list of vague catch phrases that can deceive the unwary buyer) for buying permanent paper products, and then two pages of simple instructions for making and using a special film to get the Russell Effect, which like the Photographic Activity Test can be used to test the suitability of storage materials. When placed in contact with the prepared sensitive film, materials will form an image if they are oxidizing. (3B1.22)

"Exposure of Deacidified and Untreated Paper to Ambient Levels of Sulfur Dioxide and Nitrogen Dioxide: Nature and Yields of Reaction Products," by Edwin L. Williams II and Daniel Grosjean. J. Amer. Inst. Cons. 31 #2, Summer 1992, p. 199-212. Newsprint and coated bleached chemical pulp paper were exposed to moderate levels of two pollutant gases, SO₂ and NO₂, under three conditions: untreated, deacidified aqueously, and deacidified nonaqueously. Exposure was at room temperature, shielded from light, at an RH of 60 ± 10%, for up to 29 weeks. Uptake was measured and reaction products were noted. As to which pollutant was absorbed more readily, the authors seem to contradict themselves: they say, "Overall, the paper samples had a substantially larger capacity for uptake of SO₂ than for uptake of NO₂." This seems fairly straightforward, but it is hard to reconcile with the next statement, which says that it took five times longer for the paper to take up a certain proportion of the SO₂ than of the NO₂.

The alkaline reserve was not used up in the tests of deacidified samples. It was presumed to be still able to protect the cellulose, but the salt formed as a result of the interaction (in this case, magnesium sulfate) may not be beneficial. Reaction products found were sulfate, nitrate, and nitrite. Newsprint and deacidified paper absorbed more gases than the untreated chemical pulp paper. Oxides of nitrogen (NO_x) are seen as a bigger threat than SO₂, since they are increasing in the environment and are hard to filter out with existing air filtration methods. (3B1.23)

"Print Durability on Carbonless and Thermal Papers," by A. Croce, F. Brizzi and S. Caobianco. Ind. Carta 30(9), Oct. 1992, p. 487-491 (in Italian). Nine samples of each kind of paper were light-aged under artificial light, indirect sunlight and in the dark, under controlled conditions. The carbonless papers faded rapidly, but the thermal papers "seemed likely to last more than 10 years under indirect sunlight," according to Paper & Board Abstracts v.26 #5, 1993. (3B1.24)

"Chemical Processes in the Bleaching of Paper in Library and Archival Collections," by Michal Durovic and Jiri Zelinger. Restaurator 14 #2, 1993, p. 78-101. This study summarizes the existing knowledge of chromophore systems in historical and modern papers and methods of removing them in the conservation lab by bleaching. (Chromophores are parts of molecules that absorb UV or visible light, thus producing a color in the compound.) Lignin has chromophores of various sorts; chromophores also exist in cellulose, hemicellulose, nonlignin polyphenols and resins. Some of them may act as precursors of oxidation or hydrolysis, so it extends the life of the paper to remove them, provided the right bleach is used. Microorganisms also produce color compounds. 61 refs. (3B2.36)

"Borhydride--wertvolle Mittel zur Restaurierung von Papier" (Borohydride: A Valuable Aid in Paper Restoration), by Wladislaw Sobucki. Restauro 4/1993, p. 260-263. (In German) Naturally aged paper was bleached by three methods: with sodium borohydride alone, with chloramine-T using sodium borohydride as an antichlor, and chloramine-T using sodium thiosulfate as an antichlor. Then it was deacidified and "structurally supported" with methyl cellulose, and aged in the oven. The borohydride improved the aging qualities of the paper, whether it was used alone or as an antichlor. It was not very effective as a bleach. (3B2.36)

"Transition-Metal Profiles in Open and Closed Kraft Fiber Lines," by Patrick S. Bryant, Kent Robarge, and Louis L. Edwards. Tappi Journal, Oct. 1993, p. 148-159. Transition metals exert a profoundly negative impact on ozone and peroxide bleaching of Kraft pulps. . . . Mill and laboratory data suggest that closure of ozone or peroxide bleach stages by cycling their effluent streams back to the brownstock washers could significantly increase concentrations of Mn and Fe in the bleach plant. (From the abstract) (3B1.5)

"Effect of Transition Metals Present in Washing Water on Brightness and Chromaticity of Bleached Kenaf Chemimechanical Pulps," by Q. Menghua and S. Shulan. Paper presented at the Second International Nonwood Fiber Pulping and Papermaking Conference, 6-9 April 1992 at Shanghai, China, vol. II, p. 1114-1122. Available from TAPPI Press for $75. Manganous, ferrous, ferric and cupric ions in washing water cause brightness loss. Cupric ions, in particular, may also cause yellowing. The addition of diethylene triamine pentaacetic acid to the washing water is recommended. (Abstract 2735 in PBA, 1993) (3B1.5)