Conservators at the National Library of Scotland face a sticky situation in this week’s blog post. This article was originally published in the NLS blog…
A conservator’s job often involves removing non archival tapes from objects which have been used as a repair; however the letter of C. F. Gordon Cumming to John Murray, dated 1885 which is part of the John Murray Archive, proved to be particularly challenging for the JMA conservator. Approximately 40% of the letters surface was covered in tape on both sides of the letter. The paper which the letter is written on is very brittle causing fragmentation to occur; subsequently the tape has been used as a repair. When pressure sensitive tape, like sellotape, degrades the adhesive migrates out of the tape and into the substrate causing significant discolouration and deterioration of the paper. Self-adhesive tapes can be particularly difficult to remove especially on a brittle paper.
An additional consideration for the conservator was the iron gall ink used by the author. Deterioration can occur if the ink is exposed to moisture which would cause blurring of the text. This had to be taken into consideration during the treatment.
The carrier film of the tape was removed by applying heat via a small hot air blower. This revealed the highly sticky adhesive layer underneath. The adhesive was removed by gently rubbing cotton swabs soaked in acetone over the surface.
Once all the carrier film and adhesive residue was removed the letter was in several fragments.
The next stage of treatment involved washing and a calcium phytate treatment. This treatment was carried out to remove soluble acidity from the paper, reduce disfiguring stains left by the tape and to help to preserve the ink. As the ink was exposed to moisture during the adhesive removal a calcium phytate treatment was necessary to help to preserve the ink and avoid future blurring. The calcium phyate treatment collates free iron ions in the ink, which are responsible for deterioration processes, and transforms them into a stable iron-phytate complex. In this stable state no further deterioration of the ink can occur. A special pocket was constructed to keep all the fragments together during washing to avoid further fragmentation and potential loss.
Once the washing and de-acidification treatments were complete it was necessary to re-construct the letter. As the letter was so fragmented and still remained brittle, even after treatment, it was decided to trap the fragments between two sheets of very thin and highly transparent paper made of Japanese paper fibres. This would help to keep the fragments together and reduce the risk of further disintegration in the future.
The treatment was successful in removing the highly damaging tape, soluble acidity was removed during washing and an alkaline reserve deposited in the paper to help to preserve the letter for the future. The calcium phytate treatment collated free iron ions in the ink ensuring no further deterioration of the ink will take place. Finally the fine papers used to line the letter on both sides allow the letter to remain highly legible which helping to keep all the fragments together.
Although this letter will never win any prizes for beauty, the conservation treatment has extended the lifespan of the letter and made it accessible to the libraries readers, as well as challenged the conservators tape removal skills!