What We Do
The staff of the Conservation department uses many hands-on techniques on a daily basis while working with materials dating from the thirteenth century to modern times. The staff uses processes such as disbinding, paste washing, washing and flattening, leafcasting, pH testing, deacidification, sewing, tape removal, mending, rebinding, leatherwork, hand sewing of headbands, encapsulating, laminating, matting, gold stamping and box-making.
Oversewing machine, used to sew
textblocks of loose pages that will
be heavily used.
To illuminate some of the processes further, there follow some short descriptions.
- High acid content makes paper turn brown and brittle. To determine the level of acidity in a document, the staff uses two methods of testing the pH. One is with an "archivist's pen" with which a dot is put on the paper that turns yellow if the paper is acidic. The other involves pH test strips which give a more exact level of acidity. If the item is valuable enough to warrant the expense of deacidifying, the staff sprays it with Wei T'o deacidification solution to neutralize the acid and leave a magnesium buffer to protect against future acid attack.
- Encapsulating is a form of protecting a document by sandwiching it between two clear polyester layers that are heat sealed at the edges. The item is free inside and can easily be retrieved if needed. This is a very reversible method, which usually makes it the first choice. Laminating is a heat process done with special archival tissue. It is less reversible but is sometimes the most appropriate choice.
- Many people are not aware that it is possible to wash paper. Paper is washed to remove acidic components, old sizing, stains or to relax creases. Filtered water is used after testing the inks to be sure they are fast.
- Paste washing is a method of removing the old spine lining fabric and glue using polyvinyl acetate adhesive and wheat paste. The pastes are applied to the spine after the book is disbound. They soften the old materials which are then scraped off.
- Leafcasting is a technique for filling in voids in paper. It entails securing a damaged page on a support frame and dipping it into a slurry made of distilled water and paper pulp. The slurry fills the void and when dry, recreates paper. Another form of filling voids is to use a piece of appropriate paper, shaped to fit and pasted in place.
- Sewing is often done by hand over flax cords or cotton tapes on a sewing frame, as it has been done for hundreds of years. It may also be done in sections on either the Singer or Oversewer machine.
Before and after conservation of a badly damaged blueprint