Programme start: 2000

CICRP: Jean-Marc Vallet

For several years the CICRP has been conducting research on the chromatic modifications affecting lead-based paints, particularly their darkening and the role of the environment in such degradation. Also based on experimental work, particularly with samples artificially aged under different conditions (temperature, humidity, UV), these efforts have confirmed that minium (red lead) transforms into a black lead dioxide (plattnerite) in slightly acidic conditions, and that one of the principal factors behind the darkening of this orange mineral is its method of fabrication. For example, the technique employed for heating white lead leads to the formation depending on temperature of crystalline substances of different colours (yellow, like litharge and massicot; and orange, like minium). This thermal reaction is often imperfect, as it is stopped while impurities such as litharge remain. These impurities are much more sensitive to deterioration than minium and easily transform into plattnerite. The work carried out has also shown that irradiation of the surface with a laser emitting near infrared radiation in continuous mode results in the reconversion of the darkening to minium, with benefits in terms of the stability of the phases formed.

Darkening of white lead

Darkening of white lead

(Monastery of Saorge; photo J.-M. Vallet)

The latest efforts have focused on the darkening of white lead, composed of lead carbonates. The first efforts were carried out on samples artificially aged in an environmental weathering chamber and on samples from the Franciscan monastery of Saorge (06). The aim is to gain an understanding of the role of organic binders in the darkening process.


There have been many publications (in the journals European Journal of Mineralogy, Phase transition, l’Actualité Chimique and Technè, as well as in congresses (ICOM-CC, LACONA, RIPAM, PNRCC and SFIIC).

These efforts have formed the topic of a doctoral study, a post-doctoral study and four professional and research Masters.)

Programme start: 2012

CICRP: Jean-Marc Vallet (director), Nicolas Bouillon, Odile Guillon

Partnership(s): Centre for Alexandrian Studies, Monique Pomey, conservator-restorer

The CICRP, the Centre for Alexandrian Studies and Mrs M. Pomey have established a research programme for the archaeometry and conservation of painted plaster and polychrome fired earth figurines dating to the 2nd century BC. This work focuses on finds from excavations carried out in the region of Alexandria (Egypt), particularly fragments of painted plaster and figurines originating from the excavation of Marea, as well as all the raw pigment discovered in these ceramics. The CICRP contributes its expertise in the field of conservation of mural and polychrome painting, pictorial techniques and binders, and scientific photographic documentation under different types of radiation.

Programme start: 2010

CICRP: Jean-Marc Vallet

Partnership(s): Leiden University, University of Amsterdam, Supreme Council of Antiquities

The purpose of the Hamâm Farâun project is to take an inventory of and preserve all the decorated caves discovered on this site since 2004. They are decorated with Coptic paintings, symbols and inscriptions dating to the 7th century AD.

They are situated on the edge of the Red Sea, in a hydrothermal context resulting in the circulation of saline solutions in the limestone fractures in the form of liquid or vapor. These solutions, particularly rich in sulfates, circulate at temperatures above 40°C (air temperature taken at the back of a cave).

The programme must also establish a protocol for their conservation.

Programme start: 2011–2012

CICRP: Jean-Marc Vallet (French coordinator)

Partnerships(s): Historic Monuments Research Laboratory (LRMH), University of Reims, IDK (Germany), IESL-FORTH (Greece), IGN, MAP-GAMSAU, Avignon Art College (ESSA), Chartreuse de Villeneuve-lès-Avignon, SINOPIA restoration workshop, Regional Conservation of Historic Monuments (CRMH) Languedoc-Roussillon

The goal of this programme, which complements the previous one, is to evaluate the feasibility of using infrared thermography as a non-destructive technique to detect voids or any other modification affecting a heritage work (mural painting, painting on wood or canvas, contemporary art on resin) under the surface. This initiative falls under the CICRP‘s largest project aiming to evaluate an array of non-invasive and contactless techniques, the combination of which would allow the creation of a remote diagnostic solution for the state of preservation of these heritage works.

Several data acquisition campaigns have been carried out on roman paintings from Villa Kerylos in Beaulieu-sur-Mer, the Saint Pierre chapel in Villefranche-sur-Mer, the painted ceiling of the Père Prieur’s cell (Chartreuse de Villeneuve-lès-Avignon) and the painted chapel of Innocent VII (Chartreuse de Villeneuve-lès-Avignon).

This project has been extended with the Franco-German collaboration with the IDK laboratory of Dresden following the programme ‘Stimulated infrared thermography study of the diffusivity variations with depth in cultural heritage property’ held over the period 2011–2012 under the Hubert Curien projects of the Ministry of Foreign Affairs.

Programme start: 2005

CICRP: Philippe Bromblet, Vincent Mercurio

Partnership(s): Municipal Archaeology Department, Heritage Workshop [Atelier du patrimoine], City of Marseille

For several years, fragments of ancient painted plasters found in the excavation sites of Marseille have systematically formed the object of in-depth analyses to determine the nature of the constituent materials (support and painted layers) as well as the production technique. The purpose of this research led in collaboration with archaeologists is to retrace the evolution of the painted decoration techniques used in the construction of the town since its foundation in the 6th century BC.


  • D’ovidio A.-M., Bromblet P., Mercurio V. and Vallet J.-M. (2010), ‘Etude des enduits peints trouvés sur les chantiers archéologiques de Marseille antique : premières analyses des matériaux et techniques’, in Minbar Ai Jamiaa, 20, Actes de la RIPAM 2, Marrakech, 2007, p. 243–253.
  • D’ovidio A.-M. and Bromblet Ph., ‘Ancient wall plasters found in archaeological excavations in Marseilles (France): evolution of techniques and materials’, Proceedings PRO78 of the 2nd Historic Mortars Conference HMC2010 and RILEM TC203-RHM Final Workshop, 2010, Prague, p. 119–127.
  • D’ovidio A.-M., Bromblet Ph., ‘Les enduits peints du site archéologiques du collège Vieux-port à Marseille (510-450 av.J.-C.) : étude des pigments’, in Les enduits peints en Gaule : approche croisée, 2012, p. 243–246 (31st RAE suppl.).