Conservation of three volumes in the Cambridge University Press Archive

Imagine having to file your financial year-end invoices in one of these mammoth volumes!

Figure 1: Press Conservator Sally Kilby with an invoice book, for scale

The Cambridge University Press Archive contains three oversize ‘stationery’ bindings that hold Press invoices dating from 1914 to 1922. They are extremely large, all three volumes are half-bound in leather (on the spine and the corners), and by late 2020, their condition had reached the stage where they could not be consulted or handled without conservation assessment and treatment.

Figures 2 & 3: The large invoice books are designed to open with a flat, hollow spine, and the invoices are tightly folded horizontally, adhered along the top edge and accessible only by careful unfolding and untucking from the invoices above and below

Upon assessment by the Press Conservator, Sally Kilby, three main condition concerns were identified. First, the half-leather binding was suffering from acid deterioration (also known as red rot). Red rot is thought to be caused by the absorption of pollutants in the atmosphere throughout the lifetime of the leather, or from additives included during the manufacturing process.

Figures 4 & 5: Red rot in leather presents as a powdering reddish-orange surface texture. The leather fibres lose cohesion, and handling of the volume causes loss of the loose upper layers of the leather (often onto hands or storage wrappers).

Secondly, it is common for bindings that are designed to have additional bulk added (via the pasted invoices) to have strips of paper known as ‘compensation guards’ sewn into the spine: this allows for the expansion of the text block without causing the opening edge of the book to be thicker than the spine. However, for two of these volumes, the vacant space between the short, stubby guards and the thick layer of pasted invoices had allowed the pages to ‘pleat’ and distort.

Figures 6 & 7: The short folds of paper known as ‘compensation guards’ are sewn into the text block at the time of binding – they provide extra space between the paper pages to allow for the additional bulk of the pasted invoices.
Figures 8 & 9: The gap between the bulk of the guards and the edge of the (also bulky) pasted invoices allowed space for the paper in between to ‘pleat’. This is largely because without the bulk between each page in that area, there was nothing to prevent the pages being pushed towards the spine as the large volumes were opened and closed.

Finally, there were also a considerable number of tears along the exposed edges of the text block paper.

Figures 10 & 11: Examples of paper tears. The weight of the pages (and the invoices pasted to them) caused the pages to tear in the same place as each was turned and handled.

These three condition categories informed the order of conservation requirements. First, the red-rot affected leather was consolidated with a conservation-grade consolidant (x2 applications of 1% Klucel G in isopropanol).

Figures 12-14: Conservators undertake a considerable amount of testing before applying a treatment to a collection item. Here, various methods and percentages of consolidant application are being tested on test pieces of leather, prior to applying it to the Press invoice books.

After this, the volumes were cleaned, page-by-page.

Figures 15 & 16: Due to their size, the lower half of each volume was cleaned first, then the books turned around and the upper half cleaned. Vulcanised rubber smoke sponges were used to pick up years-worth of soot and surface dirt.

Then, the warped boards (covers) were flattened. The leather on the corners and spine was carefully removed and stored, and a humidification method was designed that would allow the slow introduction of moisture (via water vapour) to the boards. As this moisture very slowly relaxed the fibres in the boards, they became more pliable and after a few hours of gentle humidification they were placed between stiff, heavy wooden boards and clamped in place. The book boards were left in these clamps for seven days, then placed under heavy weights and slowly released over a period of two weeks, allowing them to adjust to their new, flatter positions.

Figures 17 & 18: The leather on the spine and warped board corners was carefully removed and stored. This allowed for safer handling of the volumes during conservation treatment, and better access to the spine.
Figures 19 & 20: The boards were humidified and then clamped between stiff wooden boards and layers of protective materials. After 7 days the clamps were removed and replaced with heavy weights, which were slowly removed over a period of 2 weeks.

The pleats in the text block were addressed by filling the gaps between the compensation guards and the bulky invoices with conservation-grade paper and board. This has encouraged the text blocks to return to their proper shape, and the material used to fill the gaps (known as interleaving) will remain for as long as necessary (likely a year, or longer) to allow each book’s pages to retain the memory of their new shape.

Figures 21 & 22: Each section of interleaving was cut and gathered to exactly the right size. Here, Press Conservator Sally Kilby is ensuring the right amount of interleaving is inserted.
Figures 23 & 24: An example of an invoice book before and after interleaving and board flattening. The gentle pressure applied by the interleaving has shifted the text block pages back into their correct positions.

Paper repairs were then undertaken using an acrylic-toned Japanese repair paper. They were adhered using a reversible adhesive (wheat starch paste), which will allow them to be removed in the future if necessary.

Figures 25 & 26: Before tear repairs
Figures 27 & 28: After tear repairs

Next steps will involve strengthening the attachment of the boards to the spine and replacing the previously removed leather with a new spine and corners. The original leather with either be placed over the top of the new material (to preserve as much of the original design as possible) or retained and stored with the volumes for future researchers to consult.

One comment

  • Gae=ry McCormick

    Interesting to see such wonderful care being taken of an historical book. Can’t wait to see the final result.

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