Maurizio Aceto, Dipartimento di Scienze e Innovazione Tecnologica, Università degli Studi del Piemonte Orientale*: A state-of-the-art report on the analytical characterisation of purple codices

The purple codices are a small group of religious manuscripts, produced in Late Antiquity and the early Middle Ages, in which purple parchment was used as a support for writing with inks made of noble metals (silver and gold) and, in rare cases, for miniature paintings. It has long been assumed that the purple colour was obtained with Tyrian purple, the famous and highly prized dye produced from Murex molluscs. However, in the surviving medieval recipes, there is no mention of the use of Murex for dyeing parchment. Furthermore, in earlier research on purple parchments no direct evidence of Tyrian purple was found.

Apart from the historical and artistic aspects, the analytical characterisation of these purple codices is of great importance from the conservation point of view because of concerns about possible treatment procedures to be applied to the manuscripts and about the light sensitivity of the dyes. While the dye obtained from Murex is highly resistant to light the purple color obtained from species of lichen (i.e. orchil or cudbear) or folium, the dye obtained from the Chrozophora tinctoria plant, is very fugitive. For these reasons scientific research on the purple codices has recently gained interest among conservators and curators, allowing analytical studies to be carried out on the Vienna Genesis and the Codex Petropolitanus (6th century, Vienna, Österreichische Nationalbibliothek) [1], the Codex Brixianus (6th century, Brescia, Biblioteca Queriniana) [2], the Codex Purpureus Rossanensis (6th century, Rossano Calabro, Museo Diocesano) [3], the Codex Argenteus (6th century, Uppsala, Universitetsbibliotek), the Evangelistario di Sarezzano (6th century, Tortona, Archivio Diocesano), the Coronation Gospels (8th century, Vienna, Kunsthistorisches Museum) and the Salterio di Angilberga (9th century, Piacenza, Biblioteca Passerini-Landi). Preliminary analyses using only non-invasive methods have suggested that lichen dyes or folium, rather than Murex purple, were used to impart the colour to the parchment. In the coming months another 6th century codex, the Sinope Gospels (Paris, Bibliothèque nationale de France) and other early medieval purple codices will be analysed and all of these results will be summarized in the poster.

Besides non-invasive techniques, powerful analytical techniques such as Surface Enhanced Raman Spectroscopy, MALDI-ToF-MS and HPLC-MS can be applied in a micro-invasive way, allowing a reliable identification of the dyes used to colour the parchment; knowledge of their state of deterioration; identification of the species of origin of any lichen dyes present; and insight into methods used to apply the dye. The potential of micro-invasive techniques to be presented in the poster will be based upon the current study of a detached fragment of purple parchment from the Codex Brixianus that is being carried out at Università del Piemonte Orientale and Università di Torino.

REFERENCES

1. M. Aceto, A. Agostino, G. Fenoglio, P. Baraldi, P. Zannini, C. Hofmann, E. Gamillscheg, First analytical evidences of precious colourants on Mediterranean illuminated manuscripts, Spectrochimica Acta A 95, 235 (2012).

2. M. Aceto, A. Idone, A. Agostino, G. Fenoglio, M. Gulmini, P. Baraldi, F. Crivello, Non-invasive investigation on a VI century purple codex from Brescia, Italy, Spectrochimica Acta A 117, 34 (2014).

3. M. Bicchieri, The purple Codex Rossanensis: spectroscopic characterisation and first evidence of the use of the elderberry lake in a sixth century manuscript, Environmental Science and Pollution Research, 21, 14146 (2014).

*In collaboration with:

  • Angelo Agostino, Gaia Fenoglio, Monica Gulmin,& Ambra Idone, Dipartimento di Chimica, Università di Torino
  • Pietro Baraldi, Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia
  • Christa Hofmann, Österreichische Nationalbibliothek, Conservation Department, Vienna
  • Cheryl Porter55Montefiascone Conservation Project, Montefiascone (VT)
  • Abigail Quandt, The Walters Art Museum, Baltimore, Maryland