Preservation and conservation
When material comes into the archive, curators and conservation staff assess it to see if it has suffered any damage, and to check for any inherent dangers in its existing packaging. Depending on the condition of the material, it is usually repackaged in archival quality boxes and stored safely in the strong room. Some items are put aside for immediate repair or treatment, or identified for later conservation.
Physical preservation of the collections is fundamental to our work. It includes the following activities:
- We store items in an environmentally-controlled strong room to keep the temperature and humidity at a stable level. This will arrest any further deterioration of material that has previously suffered damage.
- We keep all material in boxes, folders and wrappers to avoid light damage and to keep pests away. For most material, acid-free wrappers are used, to avoid contamination of the material by acid chemicals.
- We use inert polyester sleeves to provide protection and support for individual items such as photographs, maps, or paper documents with fragile edges.
- We remove items from albums and files if they are vulnerable to further damage, preserving their original order by keeping them in the same sequence. Evidence of the original wrapping system is kept in some cases.
- We replace pins, paperclips and staples with brass paperclips which will not rust.
- We use flat unbleached cotton tape to tie bundles of documents together.
- Fragile seals are wrapped for protection against knocks and further damage.
- We provide rare books and manuscript bound volumes with purpose-made boxes fitting their exact dimensions.
- We clean books and documents that are dirty, because dust can harbour pests and encourage the growth of mould.
- We clean items that have evidence of dormant mould spores present on them, using equipment which has a suction effect to remove dust and spores.
Archival packaging to keep documents and books safe
Conservation is a complex technical procedure carried out by professionally trained conservators and their assistants in the Conservation Workshop. It can be very time-consuming and expensive. The selection of material for conservation needs to take into account the condition of the item and its potential use. As there is more material requiring attention than can be fitted into current programmes, documents which are requested by readers cannot always be repaired quickly. They may be prepared for supervised viewing or copying, to satisfy demand until they can be fully conserved.
Printed books are sometimes re-bound, using external specialists, but very old books are often studied as much for their physical make-up as for their contents. Recent conservation work on the Wollaton Library Collection has focused on stabilising the medieval structures and retaining original sewing evidence, instead of fully re-binding.
Medieval sewing evidence in the spine of WLC/LM/11
Conservation work is generally carried out by hand, in a skilled and delicate process. Conservators may need to replace lost patches of parchment or paper, and to strengthen material that has become weak, pulpy or brittle. Inks and pigments can be ‘consolidated’: that is, fixed more firmly to the page to avoid them flaking or rubbing off.
The guiding principles of modern professional conservation are that repairs should be reversible, and that they should use similar materials to the original document so that the repair reacts in the same way as the original to fluctuations in humidity, temperature and light and does not distort. This is in contrast to some very invasive, heat- or chemical-based techniques used in the nineteenth and early twentieth centuries. Sometimes this has caused the documents to deteriorate further and our conservators need to repeat the repair process.
Series of paper documents which show uniform damage are suitable for less labour-intensive treatments. Many items from the very extensive series of Presentment Bills in the Archdeaconry of Nottingham archive had fragile edges and areas where the paper had been lost. They have been mended and strengthened using the ‘leaf casting’ technique, in which new paper pulp is added to damaged areas of the document.
Bundle of presentment bills before and after leaf casting treatment
Single leaves of paper are placed in a tank of water in the leaf casting machine. New paper pulp of a similar nature to the original is added to the tank and drawn by suction through the damaged areas of the paper, before being left to dry. This is much quicker than repairing the damaged areas by hand. After strengthening the paper by adding ‘size’, the conservator cuts off any excess material, and packages the conserved documents in acid-free folders.
Next page: Handling material in the Reading Room