| Abstract: | SUMMARY. The consortium, driven by expertise of five research laboratories, two of them in end-user institutions, and one in an institute involved in instrument production for the scientific market, ensured a highly focussed approach leading to the following results: - Construction of a state-of-the art chemiluminomctric instrument, the first of its kind. The measurement procedure is straightforward: a sample (even a complete object) is simply inserted into the instrument and the emitted light can readily be measured - degradation of paper at room temperature can virtually be seen. The instrument allows the use of humid atmosphere, which is known to affect degradation of cellulose and paper, and it also allows the observation of samples without destructive sampling. The instrument is a valuable addition to the conservation scientist's laboratory, and is already commercially available.3 Its use extends well beyond conservation research, as it may be used for degradation studies of a variety of organic materials, including e.g. food. - Using the chemiluminomctric approach and a variety of other methods, details of the cellulose oxidation process were elucidated, such as the influence of carbonyl groups.4,5 It is thus recommendablc to wash any degradation products out of paper and to perform a reduction pre-treatment of paper to be deacidified, if possible. Application of advanced kinetic calculations to chemiluminometric data lead to development of degradation software with which we can predict rates of degradation at room temperature6,7 These data are of extreme importance for the collection manager, as accelerated degradation experiments performed in ageing chambers arc of little significance for ageing during storage conditions. In future applications, such prediction methods may allow the conservation scientist to evaluate a conservation treatment on an original, as only a micro-sample is needed.8 Using a newly invented analytical technique, it was shown that the content of peroxides during oxidation of cellulose is extremely low9 - this led to the conclusion that antioxidants with the role of radical scavengers might not be very effective for stabilisation of paper. Relative humidity was shown to have an extremely important role during degradation of moderately alkaline paper - by correctly adjusting the relative humidity level, an up to 10-times decreased rate of degradation was observed at the conditions of study.10 This research indicates an important future line of study, which should lead to better guidelines for long-term storage conditions. A comprehensive set of experiments was performed at four temperatures of accelerated ageing, allowing us to extrapolate the ageing behaviour of a variety of treated models and real historic papers to room temperature. Thus, we obtained the data on stability of differently treated papers (containing CaCO3, MgCO3 selected anlioxidants) at the conditions of use. By comparison of natural light-ageing with three different experimental techniques of artificial light-ageing, we produced guidelines for the conservation researcher on how to conduct studies on photo-stability of paper. Our studies have shown an extreme sensitivity of photo-aged papers towards later oxidative ageing in darkness." This leads to the conclusion that for exhibited objects, the deacidifi-cation also has to be carefully selected: MgCO3 and halides showed a stabilizing effect. Manual deacidification of paper using aqueous solutions of Ca(HCO3)2 MgíHCO3)2 and Ca(OH)2 were carefully optimised regarding concentration of the alkali, time of immersion, the resulting pH and alkaline reserve. At the project completion, members of the project, in cooperation with other renowned scientists from the field, have set to write a book on paper degradation, summing up the recent advances. - The Papylum webpage became an important resource of information and literature data on paper degradation. The database will continue to be developed in the future: http://papylum.uni-lj.si Research within the Papylum project thus lead to construction of a new valuable tool for the conservation researcher, the most important result. Using the tool, and a variety of other optimised and even newly developed methods, a profound understanding of cellulose oxidation was gained. The extensive experimental plan using altogether more than 150 different paper samples lead to data on rates of degradation at storage conditions and during irradiation with daylight during exhibitions - on the basis of such information, the collection manager is able to choose the optimal treatment. The chemiluminometric approach has already led to first useful implementations outside the Papylum project, e.g. studies of laser-treated paper12,l3 and of cotton textiles.'4 This demonstrates the validity of our research directions. The project also points to topics important for future research. On one hand, guidelines and risk assessment for storage conditions should be evaluated, especially regarding recommendations on relative humidity. On the other hand, lignin (not an object of our study) was shown to exhibit strong chemilumincscence during oxidation - the newly developed methodology could thus help solving other acute problems in conservation and preservation of paper-based cultural heritage for the future. The developed chemiluminometric technique deserves to be explored further in the area of cultural heritage materials of organic origin, e.g. textiles, varnishes, synthetic polymers, etc. |
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