The Stability of Printing Inks
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_93_141_171.doc |
| Abstract: | SUMARRIES. After an introduction to printing inks, their origin, their composition and their use, a report is given on exhaustive testing of the stability of black and colored printing inks, also when they are stressed by light and by damp heat accelerated aging. The general result confirms the observation of book conservators: the permanence of printed books is governed by the permanence of their paper. This is true for inks used for offset printing, the most widely used printing process. Printing inks are quite stable: much more stable than colored documents. CONCLUSION. The Centre National des Lettres du Ministere de la Culture et de l'Education Nationale is one of the rare authorities that is interested in the conservation of printed records. The problem of permanent paper has been resolved in France for many years, but the compatibility and the stability of printing inks on permanent paper has not been researched. That is why we performed this study. A bibliography limited our research to the main book-printing process in France: offset. The inks were selected in close collaboration with the main manufacturers in France. A preliminary study directed us to select inks that seemed compatible with permanent paper. The whole four-color process scale was examined: 15 black inks and 11 colored inks (2 cyan, 4 magenta and 5 yellow). Samples composed with various forms used in the offset process were printed with a current sheet-machine in the EFPIG workshop. They were subjected to two kinds of accelerated aging: moist heat and light. Previous modifications were noticed by measuring optical density, color and pH. Black printings keep their chemical and visual qualities before and after artificial aging. The stability of offset-printed texts is thus certain if permanent paper is used. Quantification trials of printing qualities were realized according to two technologies: abrasion results were not conclusive, but measurements suggested a black ink classification according to penetration in paper. The tested colored printings showed more disparity. They are not really affected by the damp heat aging; light exposure changes magenta and particularly yellow printings. Fading, which could reach total discoloration in some yellow printings, is then observed on most printings. A careful choice of inks could improve the printing stability: printers should select the strongest and most lightfast ones (index >5). This study allows us to prove the compatibility of permanent paper with current printing inks used in a sheet-offset press. It specifies the perpetuity of such printed texts and warns against the instability of colored documents, which are light-sensitive. A careful choice of conservation methods for printed documents and the graphic materials used during their production remains absolutely necessary for the transmission of our cultural heritage to the future generation. |
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| ISSN: | ISSN 0034-5806 |
