PART II: The Material Science and Execution of the Gough Map

by THL Máirghréad Stíobhard inghean uí Choinne

The map was created in three phases starting in 1360 c.: first, the outline of Great Britain/ Scotland, second – other towns, and lastly London.

Recent Useful Learnings about The Gough Map – Materials and Non-destructive Tools
What is “digital restoration”? It is a rapidly growing group of techniques employed since the mid-1990’s by universities / museums to restore and study manuscripts / historical documents damaged by fading, fire, water or creation of a “palimpsest”. A palimpsest is when original text / illumination is removed mechanically from the media (i.e. parchment/papyrus) and overwritten with new text / illustration.

The Gough Map has been digitally surveyed by laser, Raman spectroscopy and most recently hyperspectroscopy and fluorescence by the R.I.T. team. Hyperspectral imaging entails hundreds of colors of light as opposed to the red/blue/green light that your digital/phone camera employs and sophisticated mathematics while consulting with the greater team determining the materials of the map in specific areas (see image of Pigment analysis tool for hyperspectral images). The University of Rochester R.I.T. team traveled to the Bodleian Library at Oxford in 2015 and 2019.

The hyperspectral analysis determined that Hadrian’s Wall is not composed of the same material as the red place name text writing. Both contained vermilion but in different amounts. Five unique red pigments were identified in use on the map. Pigments also appear different on the various substrates such as sheepskin vs. lambskin parchment. Five unique green pigments were identified by the R.I.T. team for the open waterways and five more fore inland waterways. Were they used to denote tides? Crossing spots? River depths? The answers to these questions remain unknown today.

One green pigment was shown to be a mixture of indigo (woad) and a yellow pigment. Analysis showed it to not be orpiment but an organic. It was not believed to be saffron due to the expense but possibly buckthorn yellow. Further analysis discovered verdigris (copper-based green) pigment. Similar analysis will also be used to determine which map areas employ iron gall and carbon inks. I will exclusively use iron gall ink.

A typical system is the University of Rochester (R.I.T.) multispectral system. The R.I.T. hyperspectral system has an enhanced light source subsystem (see difference between images of text from Rediscovering text in the Yale Martellus Map, Spectral imaging and the new cartography). Multispectral imaging is used to recover lost text in damaged and illegible manuscripts. Researchers photograph the object under several different wavelengths of light. The images, when processed and combined, allow the researchers to see material undetectable by the naked eye (see image Illuminating the Past). They are portable and have been brought to many international locations: university libraries, museums, monasteries, and archives to name a few.

Recreating the ‘London Vignette’ from The Gough Map
What/Why: My desire to recreate a portion of the Gough Map using period materials, techniques and tools resolved into choosing the London Vignette “Plus” (LVP). London is a well know place in Britain including gold leaf (the name “London”, palace spires) and silver leaf (round windows, battlements) adding to the complexity. The palace roof, appearing green, was originally blue woad. Recreating this portion using the latest scientific research, allowed sharing the exciting new field of digital restoration.
To fully use the piece of parchment donated, I enlarged the London Vignette (LV) from the image on the website to the slightly larger image calling this “The London Vignette Plus”.

Parchment: Gail Kelloge Hope (Mistress Abigail, my parchment mentor) donated the 5 by 7-inch sheep parchment she prepared to this project. I have participated in workshops preparing it as well.

Stylus: According to the British Library and Portable Antiquities Scheme, solid lead styli were used for ruling lines/sketching in the medieval / post-medieval periods. A holder called a ‘plummet’ may have been used to hold the stylus. Images are in Christopher de Hamel’s “Scribes and Illuminators (Medieval Craftsmen). Carbon graphite was not used before the seventeenth century. Due to health hazards, a graphite pencil stylus was used.

Templates: An inquiry was made to The Manuscripts Reference Team at the British Library, Randy Asplund (Master Ranthlfr) and via social media A&S site to Mark Calderwood, noted calligraphy expert, regarding images of templates used. The BL and Mark Calderwood directed me to model books. However, knowing the model books existed did not explain exactly how the models were transferred to the parchment. This is explained in “Introduction to Manuscript Studies” by Raymond Clemens and Timothy Graham. As early as the eleventh century, “pouncing” (not pouncing for preparing parchment) was used. A copy from a model book was selected. Another piece of parchment was placed beneath the original. Pricks with a knife point/needles penetrated both pieces of parchment outlining the figure. The parchment underneath was removed, placed over new parchment and rubbing with a cloth bag filled with chalk/ powdered pigment. A sketchy outline was left on the parchment below. Simply connecting the dots completed the duplicate model. Since the single buildings on the Gough Map only have four pricks, lines were most likely hand-drawn to complete the building. I developed a parchment template for use with a bag of pigment/needles to reproduce the repeating single buildings.

Binders/Mordants for Metal Leaf and Calligraphy: Reflectance FTIR (Fourier Transform Infrared Analysis) and hyperspectral analysis has been unable to determine the difference between egg white glair and gum arabic in period samples/modern control samples. In the areas identified by the R.I.T. team as using a binder, I used gum arabic for both gouache and ink. Cennini’s classic recipe for gesso mordant for metal leaf may very well have been used on the Gough Map as it was certainly in use during the fourteenth and fifteenth centuries. Without the mordant identified, Cennini’s slaked plaster recipe was used which is a combination of honey, slaked plaster, hide glue, Armenian bole pigment and water. It was prepared by my Laurel, Roberta McMoreland (Pam McDermott) and me.

Gold Leaf: The gold leaf used for the gold elements is 24 carats as was used in period. Shell gold I prepared in the medieval manner was used to touch up to the edges of gold leaf in the medieval manner as described in my paper “Preparing Shell Gold”. (image Gilding before cleaning – photo by author)

Silver Leaf: The silver leaf used on elements such as the battlements about the London palace or “castle” tarnished with age. This is a well-known phenomenon for silver gilding. It will not appear tarnished in the reproduction – at least not initially.

Pigments: A table included in the full paper was devised showing how many pigments were identified by scientific analysis by the R.I. T. team, which pigments were identified in the LVP, their modern substitutes if used, binder used, and some additional notes. A nominal ratio of 1:10 with enough water to make a preparation roughly like melted ice cream was used for gouaches. Some pigments must be mulled with water using a glass muller against marble before use as was the case with the woad (indigo) pigment.

Preparing to mull the woad (indigo) pigment and gum arabic with glass muller against marble slab. (Photo by author)

Pigments: mixed into gouache with gum arabic with burnisher. (Photo by author) Note that disposable gloves and a disposable mask were used when preparing the vermilion and for post-drying handling due to toxicity.

Pens/Ink: Undoubtedly quills were used to prepare the map which was attached to a stretcher when being worked. I am using goose/crow/turkey quills prepared by Robert Meyer (THL Robert L’Etourdi) or myself. I am also using oak gall ink prepared also by Robert Meyer since the complete study of the inks used on the map is incomplete. However oak gall ink is one of the inks common to the era. “Vermilion” red ink was prepared by mixing gum arabic with vermilion pigment in about a 1:20 ratio then with 30 parts of water. As discussed by Christopher de Hamel in “Illuminators and Scribes”, since making quills was such a common and oft used skill in the middle ages, no known primary source documentation is known describing the process.

Burnisher: When burnishing the gilding, I used a dogtooth burnisher with an agate tip – very hard and smooth and shaped like a dog’s tooth with wooden handle. This approximates the tool used in period except the burnishing tip was actually a dog’s or a cow’s tooth.

Calligraphy Hands: T. M. Smallwood noticed that the revisor scribe of the map uses Secretary letter forms. He made this part of his argument for a new, later date of the map. The Secretary letter forms do show up only in the revised part of the map and not in the text in the original scribe’s hand. They do not appear in place-names in Scotland for example. The LVP is from the part of the Gough Map that included revisions. The Anglicana script was used by the first scribe/calligrapher. The place names that are on the LVP were all overwritten by the revisor and have letters characteristic of the Secretary hand such as the “R” in Reigate.

Parchment: Needlework as determined from inquiries to the Bodleain, the library took possession of the map when the material joining the lambskin and sheepskin was already missing. The seam is not part of the LVP. Using the “Ask a Librarian” at Bodleian Library to find out about the seam-joining material and the exact size of “The London Vignette (LV)”. I interacted with Drs Nick Millea, Oxford Map Librarian at Bodleian Library, renowned expert on the Gough Map and author of The Gough Map: The Earliest Road Map of Great Britain and Marinita Stiglitz, Head of Paper Conservation at the Bodleian to determine this information. Unfortunately, they did not have the dimensions of the LV, so I interpolated the size using a poster from the Bodleain.

What Went Well and Not So Well

Well
• Drawing on the sheepskin parchment went smoothly. Once the parchment was pounced with gum sandarac, it accepted pencil, quill ink and gouache most readily. Pencil and ink were easily removed by scraping.
• Initial mixing and testing of the vermilion ink were successful when used with the quills but the ink was unstable.
• Finding the place names using the interactive map was successful but time-consuming. Understanding that you could search on part of a medieval place name i.e. “gate”, and the map would display all the locations including those letters in the name place on the map, I was able to identify the places in the LVP thus making sense of the calligraphy identifying familiar locations such as Rochester Cathedral. When a place name could not be located, it was omitted for future addition. Place names used are included in the full documentation.
• Mixing the pigments with dry gum arabic and water went very well. Mulling the woad (indigo) pigment with gum arabic using a glass muller against marble slab resulted in much finer pigment particles. The vermilion pigment required a drop of isopropyl alcohol to reduce the surface tension allowing particles to mix with water.

Not so well
• Drawing small figures with quills being left-handed and not yet having perfected beveling was a challenge. Blotting ink in roof corners for example was corrected by scraping excess ink and burnishing the parchment laying the nap flat.
• Although initial mixing of the vermilion ink tested successfully, overnight, the ink settled. Perhaps additional gum arabic /egg glair or a drop of isopropyl alcohol would have helped. In the future I would experiment with formulations and vermilion hues to match the color better perhaps using spectral data from the actual map analyses.
• Gilding in low humidity conditions is always a challenge and with period style a greater challenge. The gold leaf adhered better than the silver leaf despite attempts to increase the humidity in the room using steam. Given the dry, cold weather and impending snow, this was not unexpected. If time allowed, I could have scraped the gesso off, added a drop or two of honey to it and started over.
• Knowing how much sap green to mix with the woad (indigo) to achieve the green for the hills was a challenge. I matched the color as best I could to the poster in tests, but that does not mean it reproduces what was originally used. Controlled tests of various mixtures submitted to simulated aging might be able to spectrally find the original mixture. An inquiry to Dr. Messinger regarding the green pigment analysis was not answered until after completion.

Conclusion
The Reproduction:

Image: My reproduction of the Gough Map London Vignette Plus (Photo by author).

Further Developmental Studies
There are years of analysis and discovery to be done on the map and other historical documents including: minimizing imaging light exposure to avoid possible long term damage, spectrally “unmixing” pigments, recovering text and damaged areas using fluorescence, automating identification of pigments and creating an affordable imaging system (the R.I.T. systems cost about $50,000 – the goal is $2,000 each).

Rochester, N.Y., located in the Barony of Thescorre, is establishing itself as the world center for recovery of historical documents – whether they have been damaged by age, smoke, water or are palimpsests. The R-CHIVE (Rochester Cultural Heritage Imaging, Visualization and Education) group centered in Rochester meets (also online) alternately at R.I.T. and the University of Rochester and is a collaboration of university researchers, volunteers and students from across the globe. They have held conferences for the past three years in Rochester.

A UNESCO UK Memory of the World Treasure
Cultural heritage imaging is increasing in importance each year. The Gough Map is an excellent example. On 5/23/2011, the Gough Map was added to the UNESCO United Kingdom “Memory of the World Treasures” register. “The UK Memory of the World Programme is part of a worldwide initiative established in 1992 to ‘guard against collective amnesia, calling upon the preservation of the valuable archive holdings and library collections all over the world ensuring their wide dissemination.’.”19

Future Opportunities for Me with the Gough Map
This project was about the journey through using period tools, methods and materials augmented by modern scientific analysis of the materials not about the appearance of the finished map segment. I do hope to at sometime in the future reproduce the entire Gough Map including delightful elements such as the ship off the Orkneys. Not only does the reproduction improve my cartography/illumination skills, but the associated research broadens my understanding of the history, paleography and codicology of the exemplar, its preparers and users.

I continue my volunteer opportunities with R-CHIVE which assists me in accessing information on recent discoveries. Last year I was able to engage Dr.’s Messinger and Easton with personnel at my company, L3Harris Technologies, to discuss beginning enhancements for this use to the ENVI ™ software my company produces. This software is used to “stitch” all the images together for the non-invasive analyses. My dream is after training at the 2020 conference that R-CHIVE will host, to be able to assist in a hands-on fashion in addition to my current discussions as a volunteer with R-CHIVE for future analyses.

Interactive Website
The Gough Map Project developed a wonderful interactive website where users can explore physical aspects of the map itself as well as access papers, presentations, articles and links to other research material about the map. During the A&S competition, I shared access allowing judges/visitors to experience the interactive site onsite.

Image: The Gough Map Decoded entry at Kingdom A&S Championship by THL Máirghréad Stíobhard inghean uí Choinne, member of the AEthelmearc Parchmenters’ Guild.

This article is an abbreviated version. The full documentation, including the full bibliography, can be downloaded from here.

Abbreviated Bibliography

1. Bai, Di; Messinger, David; Howell, David, A Hyperspectral Image Spectral Unmixing and Classification Approach to Pigment Mapping in Historical Artifacts, Journal of the American Institute of Conservation (JAIC), pp. – (March 10, 2019)
2. Cennini, Cennino D’ Andrea. Il Libro dell’ Arte (The Craftsman’s Handbook. Trans. Daniel V. Thompson, Jr. New Haven: Yale University Press, 1933.
3. Delano-Smith, Catherine, Understanding the Gough Map: an application of physics, chemistry and history, accessed 9/24/19
4. Easton, Roger L.; Sacca, Kevin; Heyworth, Gregory; Boydston, Kenneth; Van Duzer, Chet; Phelps, Michael, Rediscovering text in the Yale Martellus Map, Spectral imaging and the new cartography, 7th IEEE International Workshop on Information Forensics and Security, Rome, Nov. 19, 2015
5. Kelloge Hope, Gail, Parchment – Making Basic Instructions, 10/2019
6. Messinger, David, Hyperspectral Image Analysis of the Gough Map of Britain (1410): Who? What? Where/ When? Why? And How?, Chester Carl Center for Imaging Science Lecture, R.I.T., 1/23/2019
7. Illuminating the Past, Rochester Review March–April 2017, Vol. 79, No. 4
8. A pigment analysis tool for hyperspectral images of cultural heritage.
9. Vetter, Wilfried, Latini, Irene, Schreiner, Manfred, “Azurite in medieval illuminated manuscripts: a reflection-FTIR study concerning the characterization of binding media” Heritage Science volume 7, Article number: 21 (2019)
10. Wilcox, Margaret, “Preparing Shell Gold”, Class Handout College of Three Ravens 2010; Fall Academy 2010; Pen V. Sword 2014, Summer Academy 2014; 2/15