Colouring by numbers: botanical art techniques investigated

From Richard Mulholland

[Author Richard Mulholland will give a lecture on Ferdinand Bauer and his colour code at the Weston Library on 3 June at 1 pm]

With the end of the annual RHS Chelsea Flower show on Saturday, and the masses returning to their own English gardens inspired, it’s worth looking back to the 18th century, to the golden age of botanical exploration and to an artist who was arguably the finest botanical painter in history, Ferdinand Bauer. Now the Bodleian’s Conservation Research department are helping to unravel his meticulous and unusual painting technique.

Ferdinand Bauer, Iris Germanicus, watercolour on paper
Ferdinand Bauer, Iris Germanicus, watercolour on paper (MS. Sherard 245/70) © Bodleian Library, University of Oxford 2015

Outside of the natural sciences, Bauer (1760-1826), is little known. However, along with his equally talented brother Franz, he is certainly known to botanists. He has been called ‘the Leonardo of botanical illustration’, and is known in particular for the beauty and accuracy of his illustrations of flowers. Nowhere is this seen more clearly than in the paintings he made for the exquisite Flora Graeca, one of the most rare and expensive publications of the 18th century, and certainly one of the greatest botanical works ever produced.

Unprecedented in the quality of its illustrations, its printing and its attention to naturalistic detail, the Flora Graeca described the flowers of Greece and the Levant, and was published in ten lavishly-printed volumes between 1806 and 1840, purchased by an elite list of only 25 subscribers. It was the legacy of the third Professor of Botany at Oxford University, John Sibthorp (1758-1796) who funded much of the endeavour out of his own funds. Sibthorp met Bauer in Vienna in 1786, and immediately engaged him to join his expedition to collect and record specimens, and ultimately to paint the almost 1500 watercolours of plants and animals he sketched on his return to Oxford in 1787.

 

James Sowerby (after Ferdinand Bauer), Frontispiece [Mons Parnassus] for The Flora Graeca, 1806-40, hand coloured engraving (MS. Sherard 761).
James Sowerby (after Ferdinand Bauer), Frontispiece [Mons Parnassus] for The Flora Graeca, 1806-40, hand coloured engraving (MS. Sherard 761). © Bodleian Library, University of Oxford, 2015
 What is of interest to us however is that Bauer used a particularly unusual technique to record his specimens in the field.

Bauer is exceptional among travelling botanical artists for the unusual techniques he employed for recording colour. He certainly observed and sketched live specimens, but he did not annotate these sketches with colour in the field as other artists did. Rather, subject to the limitations of working in the field – moving from place to place quickly in often difficult territory, and unable to carry large amounts of painting materials with him, he made only very basic outline sketches in pencil on thin paper.

He recorded the vital colour information, lost almost immediately after a specimen had been picked by annotating these with a series of numerical colour codes which likely referred directly to a painted colour chart, now lost. That Bauer’s paintings were created using only this colour reference system during his 6 years in Oxford, painting them sometimes up to five years after seeing the original plants, and that they are highly regarded even today for their botanical accuracy, speaks to his expertise as an artist and his astonishing memory for colour.

Page from sketchbook for Iris Germanicus showing numerical colour codes, graphite pencil on paper, 1786-7 (MS. Sherard 247/107). © Bodleian Library, University of Oxford, 2015
Page from sketchbook for Iris Germanicus showing numerical colour codes, graphite pencil on paper, 1786-7 (MS. Sherard 247/107). © Bodleian Library, University of Oxford, 2015

More pertinently, Ferdinand Bauer (and to a lesser extent his brother Franz) appear to be the only significant natural history artists to have used this kind of colour code in a practical way. Numerical codes of up to 140 different colour tones are found on early drawings by both Bauers from the 1770s. However, where Ferdinand seems to have continued to develop this initial system of some 140 colours into one of at least 273 colours for the Flora Graeca (and from then into a considerably more complex system of 1000 colours for a later expedition to Australia in 1801-5 – though how he could have used this practically is anybody’s guess), Franz Bauer, who was by then official botanical painter to Joseph Banks at the Botanical gardens at Kew, did not did not appear to use the system after he came to London in the late 1780s. Ferdinand of course, spent a significant amount of his time working in the field, and therefore much more in need of a system of shorthand than his brother. However, it’s interesting to note that no other travelling botanical artist used such a system to the extent that Bauer did.

An early colour chart (below) that appears likely to have been used by the brothers was found in 1999 at the Madrid Botanical Gardens, but Ferdinand Bauer’s 273 colour chart from the Sibthorp expedition and the 999 colour chart he may have used for the Matthew Flinders expedition to Australia, if they ever existed, have never been discovered.

Colour chart (c.1770s) discovered in the Archives of the Botanical Gardens in Madrid in 1999, and likely to have been used by the Bauer brothers © Archivo del Real Jardín Botánico, CSIC, Madrid.
Colour chart (c.1770s) discovered in the Archives of the Botanical Gardens in Madrid in 1999, and likely to have been used by the Bauer brothers © Archivo del Real Jardín Botánico, CSIC, Madrid.

This fact, however, presents a unique opportunity for us to carry out technical research into Bauer’s materials. The Conservation Research department at the Bodleian Libraries together with the Plant Sciences Department at the University are working on a three year Research project on Bauer’s techniques, funded by a Leverhulme Trust Research Project Grant. Collaborating with the V&A, Durham University and the University of Northumbria the project aims to understand what the Flora Graeca colour chart may have looked like, and how Bauer might have used it. A large part of the project involves identifying the pigments used by Bauer in his magnificent Flora Graeca watercolours, cross reference these results with the numerical codes in his field sketches, and ultimately create a historically-accurate reconstruction of the lost colour chart.

Professor Andy Beeby from Durham University setting up a portable Raman spectrometer to analyse red pigments used on one of Bauer’s paintings © Bodleian Library, University of Oxford
Professor Andy Beeby from Durham University setting up a portable Raman spectrometer to analyse red pigments used on one of Bauer’s paintings © Bodleian Library, University of Oxford

How will we do this? Often it is permitted to remove a minute sample of paint from a work of art in order to identify the material components. However this is rarely possible with works of art on paper, and is most certainly not possible for one of the treasures of the Bodleian’s collection! The work therefore is carried out in situ, bringing portable instruments to the object itself, rather than the other way around. For this we currently use three analytical techniques at Oxford: Raman spectroscopy, X-ray Fluoresce spectroscopy (XRF) and Hyperspectral imaging (Imaging spectroscopy).

Durham and Northumbria Universities have particular expertise in Raman Spectroscopy of cultural heritage objects, and Durham has built a portable instrument that is capable of positively identifying many of the pigments that Bauer used. The V&A Conservation Science section has a long history of collaborating with universities on technical research, and also has a great deal of expertise in Raman spectroscopy and its use in identifying pigments on artists’ watercolours.

In addition to the excitement of recreating Bauer’s lost colour chart, the project showcases the value of technical art history, a relatively new field that encompasses both scientific analysis and historical research into the materials and methods of the artist. It will go some way toward an understanding of Bauer’s extraordinary feel for colour and pigment, how he utilised his colour code, and ultimately how he was able to achieve such an impressive degree of colour fidelity in his work.

As we progress with the project, and as we learn more about Bauer’s materials and techniques, I’ll post again with more results. But should you find yourself in Oxford before September, a copy of both the Flora Graeca, and Bauer’s original illustrations for it are on display in the Marks of Genius exhibition at Bodleian’s Weston Library.

Installing the Red Book of Hergest at National Library of Wales; and the ungloved hand

The Red Book of Hergest, held in the Bodleian Library on deposit from Jesus College, was recently installed in the exhibition 4 Llyfr/4 Books : Welsh Icons United at the National Library of Wales.
Photos of the installation can be seen on the NLW’s facebook page.
In these pictures, we can see that during the exhibition installation some of the conservators were wearing gloves, and others not.  Cotton or latex gloves are useful for those installing exhibitions, to prevent fingerprints on acrylic book cradles and glass display cases. But they are not always required for the handling of rare materials themselves. The Bodleian Library prefers that staff and readers have  clean, dry hands – not gloves – when handling any rare books and manuscripts. The reasons are outlined in these posts from the University of Reading Special Collections and from the National Archives.

Understanding parchment

From 24-28 June, the Bodleian Libraries, in collaboration with the Oxford Colleges Conservation Consortium, hosted a workshop taught by Jiří Vnouček, of the Royal Library in Copenhagen. He led a team of conservators through the physical process of converting animal skins into parchment. At a lecture to a larger group of students, academics and library staff, Dr Vnouček related the appearance of parchment in medieval manuscripts to the process of production, drawing lessons for the technical examination and identification of parchment. The workshop, which is running for the first time in the UK, is generously sponsored by the Wellcome Trust, AMARC, Conservation by Design and the Leathersellers‘ Foundation.

Making parchment workshop

Taking revenge on wicked Lord Byron – Chris Fletcher on a ‘Byronic trophy cabinet’

Keeper of Special Collections Chris Fletcher writes in the Spectator blog about the commonplace album kept by Lord Byron’s friends, the Parkyns family, Bodleian MS. Eng. c. 7967 …

http://blogs.spectator.co.uk/books/2013/05/taking-revenge-on-wicked-lord-byron/

Bodleian MS. Eng. c. 7967, a commonplace book kept by members of the Parkyns family
Bodleian MS. Eng. c. 7967, a commonplace book kept by members of the Parkyns family

Selden Map of China – conservation news and colloquium

– from Marinita Stiglitz and Robert Minte, Conservation & Collection Care, Bodleian Library.

Since making our first blogpost on the Selden Map of China the conservation treatment continues to reveal some interesting aspects of the Map’s previous restoration.

After removal of the early 20th century textile lining and application of a temporary facing, the map was secured face down onto a perspex table to keep it flat during the removal of old paper patches from the back. This also allows constant assessment of the map’s condition with transmitted light.

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The task of releasing the many paper patches applied during past restorations to protect fragile or missing areas proved to be challenging due to the very tenacious adhesive used for their application and the thin and fragmentary paper support in these patched areas. A few different techniques were used. Some patches were carefully separated from the map by sliding a bamboo spatula in between; others were released only after the adhesive had been softened by humidifying through sympatex (a permeable membrane). Often after this delicate process the exposed map support presented loose fragments that had to be secured back to the temporary facing with funori.

During many hours spent removing the old patches and therefore closely examining the verso, a few unexpected details came to light regarding past restoration. The discovery of weave pattern imprints on the verso and fragments of an earlier textile lining have revealed that in the past the map underwent at least two separate linings. Also the patches, differing in their shape and paper type, suggest that the map was repaired more than once. The verso of the map in general presents an overall surface dirt under the adhesive layer indicating that it was kept without any lining for some time.

Fragments of the paper support, paper patches and textile linings as well as samples of adhesive from different areas have been collected to scientifically identify their origin and therefore expand further our knowledge of the map.

The collaboration with Mark Barnard (formerly of the British Library) and Keisuke Sugiyama (British Museum) continues to be extremely beneficial; most recently planning for the dying of Chinese paper to be used to infill the many losses.

Funding for the conservation work has been generously provided by The Pilgrim Trust, The Radcliffe Trust, Sir Robert Horton, The Mercers’ Company and Merton College.

The Selden Map will be the subject of a one-day colloquium at the Bodleian Library on 15 September, 2011.
See details here.
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Many uses of a piece of parchment

Bodleian Library Broxb. 97.40
Bodleian Library Broxb. 97.40, a frisket made from a recycled manuscript leaf.

The Conservation Section is currently devising a new mount for a parchment frisket cover from the Broxbourne collection. A frisket is the part of a printing press that holds the paper in place during printing. Often covered with parchment, a frisket also acted as a mask to keep inky parts of the press bed from marking the printed paper.

The frisket cover (Broxb. 97.40), which is made from a recycled manuscript leaf, was framed behind glass when it came to the library and only one side could be seen. The library’s Rare Books curators asked whether it could be unframed and mounted so that both sides could be seen, and to make it more readily available for study. Once the Broxbourne frisket was released from its frame far more information about its early use and subsequent history could be seen.

A page of a manuscript

Manuscript writing can be seen on this piece of parchment, which has been identified as a page of an Italian fourteenth-century Canon Law text.

A “mask” for printing in colour

Two centuries later, this discarded piece of parchment from a law manuscript was used to make the frisket. The frisket was used to print the red portion of an octavo-format book in the early sixteenth century, and offers early evidence of two-colour printing processes. Here, areas of parchment were cut away to allow the red-inked type to print initials and so on, while the remaining parchment masked off the text which was to be printed in black. The attached photograph shows the upper side of the frisket cover and a detail of one page in raking light, which clearly shows impressions of type.

A lining for a bookbinding

Now that the frisket cover is out of its frame it can be seen that it was subsequently used as a board lining for a large folio bookbinding.

The final question remains – what was it used to print?

– Andrew Honey, Conservation, Bodleian Libraries

Conserving 17th-century university records

Housed in the Tower of the Five Orders in the Old Schools Quad since the seventeenth century, the records of Oxford University Archives include papers from the Chancellor’s Court dating from the sixteenth century.

Over the past year a conservator has been working on the papers dating from 1634 to 1665. Amounting to just over 3000 items, these consist of single sheets and bifolia mostly on paper and occasionally parchment.

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One manuscript may consist of several pages pinned together or tied with a twist of parchment. Some feature wax seals which interestingly have leaf fragments pressed into the surfaces. (Fig. 1)

The condition of the papers was mixed. Dirt, mould damage, tears, dog-eared corners and brittle seals being the main concerns regarding safe handling. Each item has now been surface cleaned to remove dirt. (Fig. 2)

In the past the papers were probably subjected to a damp environment and high levels of relative humidity.

Mould thrives in these conditions and organic materials such as paper are a good food source for mould. The mould weakens the paper by drawing water and nutriments from it. (Fig. 3)

Fragile papers previously affected by mould were sized with a non-aqueous solution to strengthen them (Fig. 4)

Japanese papers, shaped using a water brush, were adhered to vulnerable areas to lend support. More Japanese paper was then shaped with a needle and pasted into place to fill loses. (Fig. 5 & 6)

To reduce handling, small groups of papers were re-housed together in labeled, archival quality paper folders before being returned to archival boxes. (Fig.7)

Conserving a 17th-century map of China’s trade routes

The ‘Selden Map of China’ arrived at the Bodleian Library in 1659 as part of John Selden’s bequest. It was long considered a rare curiosity until 2008, when an American scholar, Robert Batchelor of Georgia Southern University, noted that it records coastal trading routes linking the port of Quanzhou in Fujian Province with other parts of South East Asia. The map is now recognised not only as a beautiful and colourful representation of China and South East Asia, but also as a unique historical record of China’s trading activities in the early 17th century.

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Through this renewed interest, the map’s fragile condition was highlighted, initiating a detailed technical examination and major collaborative conservation and research project. The map’s vulnerable condition was already noted in conservation records from 1977, being described as “crudely mounted on paper and linen in 1919 as a hanging scroll, though not originally intended as such. The linen has stiffened, and is severely cracked in many places.”

At the time no treatment was attempted, but now circumstances allow this challenging conservation project to go ahead with the combined expertise of conservators Robert Minte and Marinita Stiglitz (Bodleian Library) Keisuke Sugiyama (British Museum) and Mark Barnard (British Library).

The extensive treatment of the 1m. x 1.5m map, using Western and Far Eastern techniques and materials, aims to stabilize the map’s paint layer and strengthen its thin Chinese paper support.

During the first stage, the map was gradually humidified by spraying purified water onto the surface from both sides using dahlia sprayers. This drew out discolouration, flattened distortions, and enabled the textile lining to be removed.

Next a temporary facing, consisting of several layers of rayon and sammoa paper, was applied on the front with funori, adhesive extracted from Japanese red seaweed, using noribake, Japanese paste brushes. The map was left to dry flat on a karibari, Japanese drying board, for a few days…

The facing protects the fragile surface whilst paper patches and adhesive layers are removed from the back. Loose fragments will be secured, missing areas infilled and new paper linings applied, restoring the map’s original flexibility and appearance.

This project will continue until next spring. Funding for the conservation work has been generously provided by The Pilgrim Trust, The Radcliffe Trust, Sir Robert Horton, The Mercers’ Company and Merton College.
History & image of the Selden Map.
For more information about John Selden’s collections, visit the Bodleian Library website.

“The Technical Examination of Old Master Drawings: a symposium in conservation science”, Clore Centre, British Museum, 20th May 2010

For about a year, I was looking forward to attending this symposium, which was organised by the Department of Scientific Research at the British Museum, with support from The Andrew W. Mellon Foundation. This was an unprecedented effort to gather conservators, conservation scientists and curators to present and discuss one of the most fascinating aspects of our work: the understanding of materials and techniques used by artists. It brought an opportunity to discuss conservation-related issues and the curatorial implications raised by scientific studies. The results from the work presented at the conference can most definitely be applied in the library context, and thus I found this conference most relevant when one considers current and future collaborations between different departments in The Bodleian Libraries, Oxford University and beyond.

The main subject of discussion were the extensive scientific studies of drawings from the British Museum and the Gabinetto dei Disegni e delle Stampe at the Uffizi, Florence, carried out in preparation for the exhibition Fra Angelico to Leonardo: Italian Renaissance drawings (22 April – 25 July 2010).

Most of the talks were tailored around a methodology of work often used collaboratively by curators, conservators and scientists to develop a conservation approach: 1. Historical understanding of the provenance of items or collections, 2. Visual examination and technical imaging, 3. Chemical analysis, and 4. Conservation treatment.

A wide range of fascinating and well presented papers on the examination and characterisation of master drawings’ materials helped the audience to learn about the latest imaging techniques, such as the recently developed near infra-red multi-band scanner (“NIR”), which is currently being used for the study of Caravaggio’s paintings at the Opificio delle Pietre Dure e Laboratorio di Restauro Firenze. With regard to new imaging techniques, I particularly enjoyed Margaret Holben-Ellis talk “Reflecting Raphael: a closer look at the Morgan’s Agony in the Garden”, an enthralling presentation of the characterisation of the media used to depict the underdrawing in this cartoon. Visualising the morphology of the pricking in Raphael’s cartoon with the HIROX 3-D microscope was a compelling new experience for most of the audience. We were unanimously mesmerised by the wealth of information obtained with this imaging technique, which will contribute to a more comprehensive art historical understanding of Rafael’s cartoons.

I was intrigued by Lara Broeke’s current work on the translation into modern English of Cennino Cennini’s “Libro dell’Arte”, the 15th century “how to” book on Renaissance Art, which, amongst many others, includes techniques and recipes for underdrawing and miniatures for the illumination of manuscripts. Lara’s work is an update after Daniel V. Thompson’s translation, and includes the acknowledgements of ambiguities in Ceninni’s text, alongside with some corrections to Thompson’s translation. These corrections are based on empirical evidence after systematic reconstructions of the recipes, such as the preparation of ultramarine pigment and bistre ink, which are both used in the illumination of manuscripts as well as in master drawings. After this talk, I enjoyed the discussions on the use of bistre and iron gall ink by artists. Bistre was a common ink in the Renaissance, but with poorer flow properties than iron gall ink (used in Europe since the 12th century). Additionally, bistre is more transparent than iron gall, making it a better option to apply washes, rather than to produce lines fluently. Non-destructive instrumental analysis carried out on a large number of drawings suggests artists constantly used both inks in combination to achieve diverse effects in their drawings.

Well known, non-contact and non-invasive (non-destructive) analytical techniques were also highlighted by several talks during the day. I was impressed with the combined use of micro-Raman spectroscopy, micro-FTIR, XRF and vis-RF to study Andrea Mantegna paintings. This study involved the characterisation of iron gall ink and other materials used in works long attributed to this artist (“Madonna della Tenerezza” and “The Virgin Mary with a Child”), confirming that areas of the backgrounds were not painted by him.

Overall, this was an extremely useful and well attended symposium, which significantly contributed to acknowledge the need to continue pioneering the study of artists’ (and makers’) techniques in the museums, libraries and archives context.

Virginia M. Lladó-Buisán, Head of Book & Paper Conservation, Bodleian Libraries

CF10: Conservation in Focus. Icon Conference, Cardiff University 24-26 March 2010

The Institute of Conservation’s (Icon) first ever conference “CF10: Conservation in Focus” was recently held in Cardiff, Wales’ vibrant capital city, to consider the broad theme of UK Conservation – past, present and future. The conference aimed to:

  • Advance and share knowledge about conservation issues in and beyond Icon’s members.
  • To have an enjoyable conference where people have time to talk and network
  • To leave Icon stronger as an organisation

The first full day of the conference consisted of a one day plenary session and focused on the two themes – ‘evidence based decision-making in conservation’ and ‘a sustainable future for UK conservation’. Highlights of the first day included an argument from Andy Calver (St. Albans Museum Service) for the use of buffering agents to control environmental conditions rather than large-scale air-conditioning systems. There was also feedback on the success of the recent ‘Conservation in Focus’ exhibition at the British Museum. I saw the exhibition in September 2008 and thought it was a brilliant concept. The display showcased the conservation of objects and allowed visitors the opportunity to meet conservators and ask them questions whilst they worked. The outcome of the exhibition seemed mostly positive allowing the conservation department to have a much greater web presence. Increased interest has led to a number of videos and pod casts of conservation work to be uploaded.

The second day provided an opportunity for the Icon groups to host specialist half day seminars. I attended the conservation science and care of collections group sessions in the morning and afternoon, highlights of which included an update on Oddy materials testing at the British Museum from Julie Phippard. The BM feels that it has a responsibility to share results of material testing and as such will publish all known results in an online database which will clearly state whether materials are safe for use within museums and archives.

The organisers of the conference had also gone to the length of creating a Facebook page for the conference (CF10: are you going? (http://www.facebook.com/#!/group.php?gid=77317902593&ref=ts). I found this incredibly useful as it allowed me to easily ask any questions about conference organisation and provided me with regular updates or news of last-minute changes.

Overall I thoroughly enjoyed the conference. It offered a perfect opportunity to chat with colleagues and a number of interesting papers were presented. The conference organisers made a particular effort to include evening social events in the main conference attendance cost so that all delegates could attend, creating even more networking opportunities. I eagerly look forward to the next conference which will hopefully have the same friendly atmosphere and flexible theme.

The full conference programme can be found online at http://www.icon.org.uk/images/stories/cf10_programme-110310.pdf

– From Jennifer Varallo (jennifer.varallo@bodleian.ox.ac.uk)