Tuesday, 19 November 2013
Many thanks to Joke in the Netherlands for telling me about this incredibly interesting conservation project dealing with a previously conserved precious manuscript involving that old demon - black dyed silk! Augusta Strand of Uppsala University Library describes the project: The book presented here was one such project just because of the special way it had been mended with silk thread and which was in great need of conservation. The manuscript dates from the 14th century and it belonged to the monastic library at Vadstena Convent after its purchase in Konstanz in 1417. The pages of the book are made of parchment and they show typical damage in the form of holes and tears that happened while the parchment was being made. Some time after the book was copied, the holes and tears have been mended artistically with silk of various colours, mainly in blanket stitch as used in embroidery. The old mending is in good shape except for those parts which were sewn with black silk. The thread is so fragile that it disintegrates on touch. During the project the black thread was subjected to colour analysis to find out which colouring agents had been used. The results showed that the black dye had been made with iron sulphate and tannin, which implies that the thread was dyed with iron filings and various plants that contain the tanning agent tannin e.g. oak apple and sumac leaves. The whole dyeing process is very acidic and if the wrong proportions of tannin and iron salt are used, sulphuric acid forms considerably accelerating the natural decomposition of the thread or material. In order to prevent the black parts disappearing completely they were treated with a glue that was applied as a spray mist. Some parts were stabilised with a thin silk gauze. Since the conservation process the book can be handled without the breaking the black thread but it still has to be treated very gently with the respect due to a book of its age. For more details and images, click here.
Posted by N E E D L E P R I N T at 19:00