Optimizing the Leafcasting Technique
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_1_04_1_14.doc |
| Abstract: | SUMMARIZE. In the context of a larger research project in the field of paper conservation several kinds of fibre were used for making conservation paper in the leafcasting machine. Accelerated ageing was performed according to EN/ISO 5630/3 (80°C 65% RH; 24 days). The samples were submitted to comparative measuring of several physical, mechanical, chemical and optical qualities. In addition to the obvious result that for conservation purposes quality raw materials must be used it was found that an addition of up to 30-40% of unbleached fibre to the leafcasting pulp resulted in the favourable chemical and optical quality and stability of the paper. Some caution is advised regarding the use of dyed fibre, because the dyes may contain metal ions such as Fe or Cu, which promote catalytically oxidative decomposition of the cellulose molecule. CONCLUSION. From the results reported above we can conclude: Paper samples containing no (samples 1, 2 and 3) or a little (4: 25%) unbleached cellulose, met the requirements of particular quality properties stated by standard EN/ISO 9706 () for permanent papers. Both their lignin content, as well as the degree of hydrolytic and oxidative decomposition before and after accelerated ageing were within the acceptable limits. A higher percentage of unbleached sulphate cellulose fibre content of up to 50% resulted in chemical parameters below the level required for permanent paper, but the difference was so small that such papers could be accepted for the intended use. The same was true for optical quality. A higher content of such fibre, however, resulted in unacceptable chemical values. There was a tendency that dyeing bleached fibre, especially using yellow dye, promoted the oxidative decomposition of cellulose molecules, and that it also had a negative influence on colour stability during accelerated ageing, probably due to the presence of metal ions in the dyestuff used for our experiment. Those ions are catalytically active even without exposure to light. Prior to using new kinds of dyestuff or pigment for leafcasting pulp, it would be necessary to determine their chemical composition. There were no problems with either mechanical strength or surface properties of paper made in the leafcasting machine, regardless of which fibre had been used. An interesting observation was that a higher unbleached fibre content, mainly produced by the sulphate method, led to higher fold numbers and better ageing stability. |
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| ISSN: | ISSN 0034-5806 |
