By Ruth Siddall, on 31 October 2018
This exhibition, installed for the month of November 2018, in the vitrine Material Museum/Museum Material in the foyer of the UCL Slade School of Fine Art, is one of the research outcomes of a project completed during Summer 2018 by UCL students Alexa Marroquin and Jessica Manuel, supervised by Ruth Siddall. Jessica and Alexa are both successful recipients of UCL Laidlaw Scholarships, which gives them the opportunity to undertake academic research in their first year of undergraduate study. Their project, ‘Red Pigments in Roman Britain’ has looked at the range of red pigments available to Romano-British artists and together they have made a comparative study of the ancient pigments available and their modern analogues; rose madder, red lead, cinnabar/vermillion and red ochre. Alexa is studying for an MSci Chemistry and Jessica is studying for a BA History of Art with Material Studies at UCL. Together they have performed scientific analyses of the pigments and also prepared pigments as paints to test their workability and colour.
Jessica Manuel (left) and Alexa Marroquin (right) and their exhibition in the Material Museum.
The Exhibition RED in the Material Museum, UCL Slade School of Fine Art
Over to Jess and Alexa …
‘Within this exhibition, RED, we have decided to include various objects that encapsulate and refer back to our Laidlaw Programme summer research project, Red Pigments in Roman Britain.Coming from a background of Art History with Material Studies and Chemistry, we have used both our interests and practical disciplines within our research to analyse the red pigments used in Romano-British wall painting fragments.
Our research started within familiarising ourselves with articles and texts that broadened our understanding of common red pigments utilised by Roman artists, most of which were taken from archaeological sites or museums and are painted objects from across Roman Britain, and also throughout the extent of the Roman Empire.
From this literature research we determined which of the analytical methods would be the most feasible and efficient to identify organic and inorganic red pigment samples such as: Red Ochres, Red Lead and Cinnabar, as well as the organic pigment: Rose Madder. Of the analytical techniques used across many other studies, we limited our research to UV-VIS, ATR-FTIR, RAMAN, XRD and Polarised Light Microscopy (PLM). We found that the most useful analytical technique was Polarised Light Microscopy, and this by far produced the most fascinating results.
By using all of these analytical techniques we were able to produce a reference data set that we can compare with the pigments found on actual wall painting-fragments acquired from an archaeological site; a Romano-British Villa at Sudbrooke in Lincolnshire. Roman wall-painting fragments were not simply painted in red, but often in bands of different coloured paint that we additionally identified as carbon black and chalk/calcite.’
Installing the Exhibition
Key to Objects in the Exhibition
1. Jar containing Mercury(II) Sulfide (HgS) / Cinnabar. This pigment, derived from the natural mineral cinnabar was considered a very valuable commodity in the Roman World. It came from the mercury mines at Almaden in Spain.
2. Jar containing Lead(IV) Oxide (Pb3O4) / Red Lead pigment. Often referred to as minium secondarium during the Roman Empire as it was considered as a second-rate pigment compared to its more expensive counterpart, cinnabar. A synthetic pigment, Red Lead was made from scrap lead exposed to vinegar fumes. This produced white lead which could then be roasted to produce this read pigment.
3. Jar containing Iron(II) Oxide (Fe2O3) / Red Ochre. The main component of red ochre is the mineral hematite, but as this is an impure, geological deposit, other impurities may also be present. The pigment in the exhibition is supplied by Rublev Colours. However ochres are ubiquitous geological deposits and they were a cheap and readily available artists’ material.
4. Jar containing Rose Madder pigment. Madder is a dye derived from the plant species Rubia peregrina or R. tinctorum. Rose Madder produces a bright-pink pigment. This pigment is supplied by Cornelissens.
5. Large wall-painting fragment from the Romano-British Villa at Sudbrook, Lincolnshire. Five different coloured bands are present. The red band was analysed by Raman spectroscopy, and hematite was identified as the main pigment used.
6. Small wall-painting fragment from the Romano-British Villa at Sudbrook. The bright-red band was analysed, by Raman spectroscopy, and cinnabar was identified as the pigment.
7. Image of Hematite crystals in Red Ochre under Plane Polarised Light. In this sample hematite crystals are finely grounded and have a deep brown-red body colour. This sample also contains crystals of yellow ochre, goethite. x 400 magnification, plane-polarised light.
8. Image of Red Lead crystals viewed using polarising light microscopy under crossed polars. Some particles exhibit emerald-green interference colour characteristic of red lead. x 400 magnification, cross-polarised light.
9. Mineral Sample of red ochre from Clearwell Caves in the Forest of Dean, England. Clearwell has been a major quarry site for ochre pigments from the Roman period to the present day.
10. Mineral specimen: Cinnabar from Guizhou Province, China.
11. Mineral Specimen: Crocoite is the mineral analogue of red lead. This sample is from Dundas, Tasmania, Australia.
12. Root of Rubia tinctorium, from which madder is extracted.
13. Paint trial of red ochre from Clearwell Caves, filled with chalk in a linseed oil medium.
14. Powdered X-ray diffractogram of Red Ochre. The sample diffracts the X-rays, producing a diffraction pattern unique to the material in question which can then be compared to an array of reference diffractograms. This technique was useful in confirming the presence of certain impurities found using polarised light microscopy.
Many thanks are due to the following people; Project Supervisor – Ruth Siddall; Martin Vickers – Senior Research Associate & Inorganic Section Laboratory Manager, UCL Chemistry; Martyn Towner – Lab Technician, UCL Chemistry; Zilu Liu – PhD student, UCL Chemistry; Jayne Dunn – UCL Culture; Alan Crease & Zoe Tomlinson – Sudbrooke Roman Villa; Jo Volley & Grace Hailstone – UCL Slade School of Fine Art.
This research was funded by the Laidlaw Scholarship Programme and undertaken by Alexa Marroquin and Jessica Manuel.