ARHIVSKI VJESNIK 3. (ZAGREB, 1960.)

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Summary ULTRAVIOLET PHOTOGRAPHY IN SERVICE OF ARCHIVISTS AND RESTORERS Ing. Tatjana Ribkin Literature very often deals with the problem of reading of hardly legible texts and texts, which cannot be seen by the naked eye, by means of ultraviolet lihgt or ultraviolet photography. It has been mentioned very often, that some kinds of auxiliary materials used in restoration (such as silk gauze and starch paste) make difficulties in reading of faded texts by ultraviolet light. One test carried out at the Laboratory of the State Archives of Croatia in Zagreb, gave an opportunity to prove practically those statements. A bundle of documents, that had fallen into the sea during the transport together with 40 such bundles, wias received for restoration from the Historical Archives in Zadar in February 1960. The action of sea water upon the text caused the fading of the ink to a high degree and made the text practically illegible. The task of restoration procedure was to try to remove sea salt, to make the text legible and prevent further destructive activities of salt. Attempts made to was out the sea salt produced negative results, because hardly legible text became even less legible by washing. Revival of the ink by means of some chemicals (stich as gallic acid) produced also negative results (Fig. 4). Photographying of one leaf of the mentioned bundle by ultraviolet light (Fig. 3) has proved this method as the only possible one to make the text legible. Figure 1. shows the same leaf photographed in normal light and Figure 2. shows the infra-red photo of this leaf. At the same time with these tests, we tried to check the data from literature te see, how far some restoration procedures make possible or difficult photographying of faded texts in ultraviolet light. »Epistolae Petrus da Vineis« from the XIV-th century was used for these tests. One part of this work was laminated by means of cellulose acetate and the other part was repaired by means of silk gauze. One leaf of this work was photographed in normal and ultraviolet light. Comparing the photograph of the

. laminated sheet with the photograph of the leaf, that was repaired in a classical way (Fig. 7) we have proved that cellulose acetate does nor hinder photographying either in normal (Fig. 5) or in ultraviolet light (Fig. 6). According to some data, silk and starch paste make difficulties, to some extant, in photographying in normal light and even more in ultraviolet light. Figure 7. shows, that silk gauze does not in the least obstruct photographying in normal light. Watching the photograph taken in ultraviolet light, we can notice the area with silk pasted with starch paste (Fig. 8). Several conclusions have been made analysing this photograph. As the first, the part of silk on good legible places of the text is practically invisible. The second, silk on the place of a dark stain caused by action of moisture can be seen very well because of its fluorescence, but in spite of that, silk does not decrease legibility of the hardly visible text. This can be explained by the fact, that the dark stain covers the fluorescence of the paper, and in such a way decreases the visibility of the text. Silk itself by its own fluorescence, decreases negative action of the stain and makes the text more outstanding. - s — 436 —