Leaves of leaves: conservation and housing of a book of Sub-Himalayan fern specimens

Eleonora Lazzari has recently completed a two month conservation internship at the Special Collections Centre. She is a student at the Cr Forma paper and book conservation school, in Cremona, Italy and due to complete her diploma in Spring 2018. While at the University of Aberdeen she worked on several projects including a 19th century herbarium (Lib R ff587.31 Fer). Eleonora worked on this project with our Book Conservator, Brannah Mackenzie, and our Paper Conservator, Louisa Coles.

19th century bound Herbarium: “Ferns from the Sub – Himalaya Hills, collected 1858-1859” Lib R ff587.31 Fer

“A Herbarium is a collection of preserved plants stored, catalogued and arranged systematically for scientific study by professionals and amateurs. […] Herbaria are used to aid plant identification, to help understand biodiversity and used in support of conservation, ecology and sustainable development.” from: Standards in the Care of Botanical Materials, http://conservation.myspecies.info/node/35#

Every herbarium must have written data accompanying the specimen. Data should include information on where and when the specimens were found and on who found them. This data is as important as the specimen itself; a specimen with no data has limited scientific value.

With this in mind, we can understand how unusual this herbarium is. Indeed, it seems to be unfinished. It is a large (625 x 460 x 650 mm) 19th century binding, with no print. The only text is a manuscript title in ink on the first page. Pages are not numbered, and there are no identification labels. There are only specimens, approximately 110 in total. The book has many blank pages at the end, and some between one specimen and another.

Specimen examples from the Herbarium

The herbarium is what is called a local herbarium. It is a collection of ferns from the sub Himalayan region. It is part of the Thomson of Banchory Collection (https://www.abdn.ac.uk/library/cld/41/) and, unfortunately, not a lot it is known about its background.

From what we know of him, Alexander Thomson did not travel to India and so did not personally collect the specimens himself. However, the binder, Edmond, based in Aberdeen, was one of the two that Thomson usually used. It therefore seems probable that Thomson obtained the fern collection and either mounted the specimens himself, or arranged for someone else to do so.

The Herbarium condition before the treatment

John Edmond, the Aberdeen bookbinder, produced bindings that ranged in quality according to price, and this is an example of his poorer quality binding. The book is a half bound leather and cloth tight back binding on boards with raised bands (bands that are raised from the spine with the leather glued directly onto them). The 19th century brown leather is very poor quality: brittle, worn, stained and abraded. As a result of how the leather was commonly processed during the 19th century, it is now very acidic and has lost too much collagen to keep elasticity and cohesion.

Note the very poor quality of the leather

As a result, the book spine was in such bad condition that it lost pieces of leather every time it was opened or moved. The sewing and the textblock are still in good condition and the specimens inside are, in general, well preserved. They are attached with paper tabs of two colours, grey and white. The white tabs appear to be a more modern paper and are therefore likely to have been applied later.

condition before the treatment from the top left in a clockwise direction: broken tabs; detached fragments; a later white tab; a specimen that has become completely detached and adhered to the facing page

Some specimens have lost some little pieces, some tabs are broken or partially detached. Two specimens were completely detached, and one of these had become adhered to the facing page.

Historically, herbarium specimens were often treated with chemical applications. These could contain harmful components such as mercury, arsenic and lead. Before the treatment was started, we contacted our Health and Safety Officer for advice. He recommended that nitrile gloves were used for handling specimens, and that extraction was used during the dry cleaning process. He also suggested that we could carry out XRF (X-ray fluorescence) analysis in order to identify a number of these elements. XRF is an analysis method to identify many chemical elements present in an object. A handheld XRF instrument was provided by the Geology department, and the analysis was carried out on two detached fragments from separate pages by a Lecturer from the same department, Dr Dave Kemp.

XRF analysis

There was no detection of mercury, arsenic or lead, which was reassuring. However, the presence of other substances such as barium and naphthalene, which were also used in some herbarium treatment recipes, cannot be identified using XRF. Therefore, as a precaution, we recommended that nitrile gloves are used by readers and staff whenever this volume, or any others containing plant material, are handled.

The treatment                                                                             

The primary aim of the treatment was to secure the loose specimens and to preserve the historical integrity of the book. A second aim was to consolidate the binding, so that it could be safely consulted.

Some pages suffered from heavy surface dirt, so the first step was to remove this with a chemical sponge and a soft brush.

The decision about how we would address the broken and partially detached tabs was straightforward. First we toned some archival paper. A tone was selected that was pretty near to the page colour, but recognisable as different.

toning paper for paper tabs

We made new tabs with this paper and we used them to reattach the specimens. The old broken tabs were left in place, to recall the original structure. The old tabs that were partially detached were reattached.

reattaching with new tabs: evidence of original attachment left in place

We consulted different people to understand which should be the best solution for the loose specimen housing: curatorial staff, an academic who consults herbaria in the course of his research, and conservator colleagues with experience of working on herbaria.

It is common practice to house loose pieces in non-adhesive paper packets called capsules.

We considered five possible solutions for housing these. In selecting the best solution, two principal factors have been considered: the safety of the specimens themselves and the requirement to view them next to the bound specimens. The final decision was to number the pages to provide a reference, then attach numbered capsules to individual sheets of paper and gather these sheets in a folder. This allowed for detached parts to be viewed next to the specimen from which they had come, without introducing any additional risk to the attached specimens

the capsule shown beside the specimens
making capsules and folder

A tray of the same height and width of the book was made, to contain the folder. A piece of plastazote was cut to the same size as the box, and a cut out made to enshrine the folder and limit movement.

Prior to starting the treatment of the pages and specimens inside, the leather of the binding was  consolidated with two different products, to make sure that it could resist  the stress introduced by opening as much as possible. Despite this, due to the brittle nature of the leather, it remained vulnerable to further deterioration. Therefore, on completion of the work on the specimens and text block, we inserted a strip of Usumino (a strong, long fibred, Japanese paper) underneath the crack on the spine to provide additional support during future use.  The areas of leather that had lifted from the spine were then readhered.

the spine before and after treatment
stages in the repair of the spine

Finally, a box was made to house both the book and tray containing the folder.

the book and the folder in the box
the final box


We would like to thank all those who offered their time and advice in the examination, treatment, and re-housing of the herbarium:

  • Roberta Bolzoni, Technician in the restoration of books, prints and documents.
  • Professor David Burslem (Personal Chair, Biological Sciences)
  • Emma Le Cornu (Conservator, Qatar Olympic and Sports Museum, formerly Conservator at Kew Gardens)
  • Lee Hampson (Clinical Scientist, Aberdeen Royal Infirmary)
  • Dr David Kemp (Lecturer, Geology & Petroleum Geology, University of Aberdeen)
  • Dr Allan Petrie (Health & Safety Advisor, University of Aberdeen)
  • Jane Pirie (Information Officer/Rare Books Catalogue, Special Collections Centre, University of Aberdeen)




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