Fastness of Printing Inks Subjected to Gamma-Ray Irradiation and Accelerated Ageing
| Main Authors: | , , |
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| Format: | Article |
| Language: | English Slovak |
| Online Access: | http://www.viks.sk/chk/res_1_02_15_26.doc |
| Abstract: | CONCLUSIONS. The colour of the print was resistant to gamma irradiation, both at the doses proposed for preservation treatments (3 kGy-10 kGy) and at decidedly higher levels (100 kGy). These latter being used to "stress" the experimental study. Accelerated ageing, an instrument used with the intention of amplifying the effects of the irradiation, caused a darkening of the paper and, consequently, of several printed areas, i.e. those with the lighter and less opaque inks. This darkening was observed only as a result of the higher irradiation doses, while the inks did not undergo any colour change, observable either to the naked eye or through instrument measurement. In comparison with the fastness indices used, no change was observed with either exposure to light or any of the solvents, as consequence of irradiation. Exceptions to this were the two inks which showed a modest reduction on the light fastness index of only one point after accelerated ageing. It should be considered that the irradiated paper undergoes, due to the synergic effect of the irradiation and the ageing, a darkening that is proportional to the dose absorbed, and, once exposed to light, it undergoes more evident colour changes than those of a less darkened paper that has been exposed to a lower or no gamma-ray dose. Therefore, the decrease in the index of light fastness for the prints of the two inks in question, inks which were not very opaque is certainly a result of this behavior of the paper. It is not possible to exclude with absolute certainty that the slight decrease of light fastness light might be due to the distribution of the ink. It would be necessary to have a support for the print without any c lour change induced by irradiation and accelerated ageing. This does not seem potable, since the paper, which conforms to the standards for the maximum fastness and durability, undergoes the same colour changes2. In any case, print tested with water, acetic acid, sodium hydroxide, solvent mixture and tetrachlorethylene maintained the same initial index, even when irradiated at the most severe doses and submitted to accelerated ageing. As was said previously, any behavioural differences between the print of the control samples and those irradiated and aged could be understood as signals of some change induced by the gamma rays. SUMMARIES. In this article the authors analyzed the impact of gamma-rays on ten of the most common printing ink in order to assess the feasibility of a treatment to disinfect/disinfest books and documents based on the use of such radiation. With the intention of highlighting the possible counter arguments against ionizing radiation, irradiation doses much higher than those indicated as suitable for preservation treatments were used and irradiated samples were also artificially aged. The fastness of different colours was evaluated following irradiation both before and after ageing. The assessment was also made of any changes induced by the irradiation on the fastness indexes initially possessed by the prints by physical and chemical agents. Print tested for the fastness to the different agents (water, acetic acid, sodium hydroxide, solvent mixtures and tetrachloroethylene) maintained the same initial indexes even when irradiated at the most severe doses and artificially. |
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| ISSN: | ISSN 0034-5806 |
