Parchment is a very durable material and even if it is quite sensitive to humidity (see previous post) it can withstand a lot of wear and tear. This characteristic has made it a favoured writing material for several thousand years. It replaced papyrus when the first multi-quire codices came into use because its flexibility and resilience allowed the centrefold of the several gatherings to be sewn together into text blocks without tearing1; and when paper became the most widespread writing and printing support, parchment still continued to play an important role in bookbinding as a covering material.
Nevertheless parchment can be damaged when documents are heavily used or misused. Tears, splitting and losses can result (figs. 1 and 2).
Repairing parchment has therefore been a necessity for many centuries. In earlier times when damage occurred along the outer edges of a document or page it was not uncommon to trim the sheet. When damage occurred within the body of the folio, different techniques to patch losses were applied including patching the damage with an additional piece of parchment or paper adhered with glue or paste.
Stitching was a more refined way to repair parchment and one that avoided obscuring the text in the treated area. This technique followed the tradition of parchment makers who would mend holes on the fresh skins with sewing threads, joining the edges of damaged areas while the skin was still on the stretching frame, and using the collagen released during the scraping process as an adhesive to further consolidate the repair.
On our manuscripts we can find an interesting array of repair techniques used during their long history (see previous post – book moth). The Book of Mulling and Codex Usserianus Primus (see previous post) have both been extensively repaired. For both of them “grangerisation” (see previous post) was carried out in the 19th century. This resulted in individual pages of the manuscripts being inlaid into paper sheets to enable rebinding. Tears and losses along the margins were mended with strips of paper (fig. 3 and 4).
In more recent times the Book of Mulling was further conserved. New spine folds were created and the losses along the margins infilled to create a compact and uniform text block for rebinding. For this treatment new parchment was chosen. The repair patches were selected according to the thickness of the original skin, shaped to match the profile of the missing area and adhered. To obtain a secure attachment between the old and the new parchment in some areas a relatively large overlapping of the two was necessary.
Some of our most important early manuscripts including the Book of Kells and the Book of Dimma were conserved between the 1950’s and the early 1980’s by Roger Powell, regarded as one of the most skilled manuscripts conservator of the times. He developed and used an improved method of executing repairs, by combining the adhesive technique with the old sewing practice and thus creating a functional and durable solution. This sewn repair was very effective because the strength of the parchment allowed fine stitches to be used without risk of tearing.
In figures 6 and 7 two different stitching patterns can be seen. In fig 6 the stitching is securing an adhered parchment in-fill while in fig 7 the stitching is used to pull together the edges of the manuscript and the patch without overlapping the text.
A development of this technique involved the use of a thin parchment strip passed through slits in the parchment, instead of the linen thread passing through holes, which further reduced the risk of tearing of the original (figs. 8 and 9).
Powell’s treatments are still regarded as high achievements in the field, however today a less invasive approach is taken. For the Garland of Howth, the Book of Mulling and the Codex Usserianus Primus a thin protein-based film called caecum has been used.
Caecum, named after the part of intestine from which it is extracted, is the modern version of the traditional gold beaters’ skin (or swim bladder) which has often been used to repair parchment. Caecum is an extremely refined material, similar in nature to the parchment and therefore compatible with our manuscript folios. Because of its thinness it is challenging to handle the tiny sections required for tear repairs, so it is supported with a facing of very thin Japanese tissue adhered with an acrylic adhesive.
Working under magnification the paper-faced caecum is cut to the size and shape of the repair and adhered to the parchment with a low temperature pure fish gelatin. Once the repair is dry a tiny amount of solvent is applied with a thin brush to soften the acrylic adhesive and remove the facing paper, leaving a strong and almost invisible repair.
Marco Di Bella, Senior Book Conservator, Preservation & Conservation Department, The Library of Trinity College Dublin