Programme start: 2006

CICRP: Jean-Marc Vallet (director), Philippe Bromblet

Partnership(s): Aix-Marseille University; Paul Sabatier University, Toulouse; Historic Monuments Regional Department of Archaeology and Conservation (CRMH) Provence-Alpes-Côte d’Azur; Mercantour National Park

The purpose of the programme launched by the PACA Regional Archaeology Department is to establish the degradation kinetics of rock engravings in the Vallée des Merveilles (altitude of sites above 2,200 m) and to establish a predictive model for the evaluation of the risks and speed of total disappearance of the engravings using different benchmark cases. Its goal is to propose methods of conservation and restoration appropriate to the different cases encountered (site, lithotype, type of degradation).

Engraving

Washed out and eroded engraving, with the development of cyanophytes

(Vallée des Merveilles, photo J.-M. Vallet – CICRP)

The work began with a study on the origin of the red surface colouring on the engraved rocks. An on-site and laboratory investigation involving several lots of engravings has revealed that the engraved stones bore different colours (orange, red, purplish), apparently through different processes. Some of these colours were the result of the transformation of the rock bearing the engravings, while others were due to deposits of mater of varied origins. Currently the work is focusing on relative dating for these colourings and the development of different approaches towards understanding the degradation phenomena and their kinetics, with the aim of determining optimum conservation measures.

Publications:

  • Poster from the 14th International Clay Conference (Castellaneta Marina, Italy, 2009)
  • Poster from the 12th International Congress on the Deterioration and Conservation of Stone (New York, United States, 2012)

Programme start: 2003

CICRP: Philippe Bromblet, Jean-Marc Vallet

Partnerships: Meknes Faculty of Sciences (Morocco), CEREGE (Aix-Marseille University)

A joint venture was launched between the Meknes Faculty of Sciences, the city of Meknès and the CICRP to study the deterioration of the ramparts and main rammed-earth monuments of the ancient imperial city. Several sampling campaigns, a university thesis and specialist field investigations have been used to shed light on the materials and construction methods used, as well as assess the primary degradations and determine methods to improve the protection of these structures.

Morocco

Measurement of the speed of sound on a block of stone

before restoration (Volubilis, Morocco) (photo Philippe Bromblet)

Publications:

  • Bromblet P., Vallet J.-M., Ajakane R., Kamel S., Mahjoubi R. and Meunier J.D., ‘Caractérisation de l’enduit dégradé d’une muraille aqueduc de l’ancienne ville impériale de Meknès (Maroc)’, Minbar Ai Jamiaa, 7, Proceedings of the RIPAM 2005, 2007, pp. 236–246.
  • Ajakane R., Kamel S., Mahjoubi R., Vallet J.-M., Bromblet P., Meunier J.D. and Bouadid R. (2007), ‘Caractérisation des matériaux et de l’altération des remparts pour une restauration adaptée : exemple d’une muraille du contrefort de Hri Souani, Médina de Meknès, Maroc’, RehabiMed, 1st Euro-Mediterranean Regional Conference, Present and Future, Barcelona 12–15 July 2007, pp. 453–456.
  • Kamel S., Ajakane R., Mahjoubi R., El Faleh E.M., Vallet J.-M., Bromblet P., Meunier J.D., Noack Y. and Borschnek D., ‘Caractérisation des materiaux de construction des remparts de la medina de meknes : exemple de la muraille de Sidi – Baba (Meknès, Maroc)’, Echanges transdisciplinaires sur les constructions en terre crue, 2. Proceedings of the roundtable of Villefontaine 28–29 May 2005, Editions de l’Espérou, Montpellier, 2007, pp. 23–32.
  • Ajakane R., Kamel S., Mahjoubi R., Vallet J.-M., Bromblet P. and Meunier J.D., ‘Impact de l’altération météorique sur les murailles de la médina de Meknès (Maroc)’, Proceedings of the International Meeting on Mediterranean Architectural Heritage (RIPAM 2005), 26–28 Sept 2005, Meknès, ENSAM, pp. 119–120.
  • Ajakane R, Kamel S., MahjoubiI R., Vallet J.-M., Bromblet P., Bouabib R., Meunier J.D., Noack Y., Borschnek T. and Guillot H., ‘Preliminary studies on the degradations of the Medina’s ramparts of Meknès (Morocco)’, Proceedings of the 10th International Congress on Deterioration and Conservation of Stone, Stockholm, 2004.
  • Kamel S., Mahjoubi R., Arsalan S, Vallet J.-M. and Bromblet P., ‘Chantier expérimental de restauration sur un bâtiment de la Médina de Meknès (Maroc) en vue d’une méthodologie adaptée’, Proceedings of the international symposium Réhabilitation et revalorisation du patrimoine bâti, 23 and 24 May 2011, Skikda, Morocco, T2, pp. 770–782.

Programme start: 2012

CICRP: Fabien Fohrer

Partnerships(s): Grazia Nicosia, conservator-restorer, National Centre of Plastic Arts (CNAP) grant; Yohanna Dechezleprêtre, conservator-restorer

This research has been carried out with and at the instigation of Grazia Nicosia, conservator-restorer and CNAP research assistant, in collaboration with the artist Ian Fabre.

This study aims to test the repellent effectiveness of essential oils used alone or in combination on certain insects currently encountered on this type of material (examples: Anthrenus verbasci, Stegobium paniceum, Gibbium psylloides, etc.).

Concurrently, a study on the chemical and physical harmlessness of these substances is being carried out on the materials traditionally used by artists, such as insects, but also bones, feathers, leather, hair and also metals and textiles. The study of these repellents, their mode of action and their user protocols will make it possible to improve the packaging and storage of these works by reducing the risk of insect infestation.

Publication:

Fohrer F., 2011, ‘Recherche de produits ou molécules de substitution pour la protection des oeuvres patrimoniales’, La lettre de l’OCIM, No. 138, November–December: 21–22.


Programme start: 2008

CICRP: Nicolas Bouillon (director), Fabien Fohrer

Partnership(s): Aurélia Chevalier, doctor of conservation-restoration, Arts et Métiers-Paris Tech

This programme is an offshoot of a larger programme on Stegobium paniceum and focuses on glue-pastes and the risk of insect infestation for traditionally relined paintings. It also encompasses a concurrent entomological study based on infestation test samples of known composition as well as the analysis of glue-pastes by GC-MS in order to correlate their attractiveness according to their chemical composition.

Pictorial layer

Loss of pictorial layer and its original support following a severe infestation

The first conclusions have addressed the type and quantity of flour used as a principal attraction factor and the presence of Venice turpentine as a plasticizer as a possible repelling factor. Physico-chemical analyses are systematically carried out on real samples taken from infested relined paintings restored at the CICRP in order to correlate the degree of infestation of works with the chemical composition of glue-pastes.

This programme also aims to develop a new natural glue-paste formula that is reversible and long-lasting in terms of effectiveness and the risk of insect infestation. This type of adhesive could constitute an alternative to synthetic linings, which can create a number of reversibility as well as compatibility problems with the original materials, and whose degradation processes and their effects are still poorly understood and controlled at present.

Support infestation

Traces of infestation by Stegobium paniceum of a glue-paste relined support

Publications:

  • Fohrer F., Basle K. and Daniel F., ‘Compréhension et analyse des phénomènes d’infestation et de réinfestation par le Stegobium paniceum des peintures de chevalet rentoilées à la colle de pâte’, Support Tracé, 2006, 6: 78-83.
  • Bouillon N., Fohrer F. and Bonnafoux B., ‘Study of pest infestation of glue paste lined easel paintings : a characterization of traditional glue paste recipes and their relevant Volatile Organic Compounds by Gas Chromatography/Mass Spectrometry’, ICOM Committee for Conservation, 15th Triennial Meeting in Delhi, India Preprints, September 2008.
  • Baslé K., Bouillon N., Fohrer F., Guillon O. and May R., ‘Pour une approche raisonnée des problématiques d’infestation en milieu patrimonial : le cas du Stegobium paniceum‘, Techné 2009 , no. 29.

Programme start: 2011

CICRP: Philippe Bromblet

Partnership(s): French Heritage Partners Circle, Historic Monuments Research Laboratory (LRMH) (director), VICAT SA

The object of this programme is to tackle questions of restoration for facades decorated with natural cement based plasters in the Marseille region by proposing a restoration plaster suited to the supports and with colours and textures close to those of these 19th-century plasters.

It includes an examination of the sate of conservation and nature of the natural cement based plasters on Marseille facades, a documentary study on this industrial activity of the 19th and early 20th centuries, as well as visits to quarries (Roquefort-la-Bédoule etc.) and factories (ovens) to sample and analyse the raw materials in order to carry out the rare analyses found in the literature.

Facade decoration

Natural cement: facade decoration of the Eglise de la Mission de France carried out in 1860

by the company Désiré Michel, rue du Tapis Vert, Marseille (photo Philippe Bromblet)

The CICRP has participated in the sampling campaign and management of a documentary research initiative on the history of the manufacture of natural cements from the Marseille region.

Publications:

  • ‘Les enduits à base de ciment naturel à Marseille : Identification et restauration’, literature survey carried out by Claire Valageas, research analyst at the French Heritage Partners Circle, 2011.
  • ‘Histoire de l’industrie des ciments naturels dans la région de Marseille’, presentation by Claire Valageas for the ICOMOS technical days (2 and 27 April 2012, Paris) Les ciments naturels dans le patrimoine européen : histoire, propriétés, applications et conservation.

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.

Publications:

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: 2010

CICRP: Philippe Bromblet, Jean-Marc Vallet (directors)

Partnerships(s): Mediterranean House of Human Sciences (MMSH), Aix-Marseille University, National Institute for Preventive Archaeological Research, Territorial Collectivity of Corsica (CTC)

For several years the CICRP has worked to gain a deeper understanding of the deterioration mechanisms affecting these granite monoliths, which at the beginning of the 1990s underwent a restoration effort that turned out to be unsuitable. The work has focused on monitoring the development of the degradation through observation and measurement of the speed of sound propagation as well as accelerated ageing specimen testing. The results obtained have shown that the degradation of the surface of carved stones had developed and that ethyl silicate combined with a waterproofing treatment (silane) seemed to offer better results in terms of durability than ethyl silicate alone or acrylic resins. The work in progress aims to determine which consolidation treatment would produce the best results in terms of durable preservation for the sculpted and highly fragile outer layer of these standing stones.

I Stantari

Corsican I Santari granite: view of the statue-menhirs (photo Philippe bromblet)

Publications:

  • Vallet J.-M., Bromblet P. & Bouillon N., ‘Du diagnostic à la conservation du Patrimoine archéologique en pierre en milieu isolé : quelle démarche adopter ? Exemple des statues- menhirs en granite d’I Stantari’, Proceedings of the roundtable CONSERVER, ETUDIER, PROTEGER LE PATRIMOINE EN MILIEU ISOLE, Mariana, 9-11 October 2008, in press.
  • Vallet J.-M., Bromblet P., Heddebaux E., Bouillon N., ‘Conservation of archaeological Megalithic sites under marine environment: example of the granitic menhirs at I Stantari (Cauria plateau, Corsica Island, France)’, Proceedings of the 12th International Congress on the Deterioration and Conservation of Stone, New York, 22–26 October 2012.

En Février 2014 le CICRP a accueilli avec les Archives Municipales de Marseille les 2èmes Rencontres de l’Inccaf (International Network for the Conservation of Contempory Art France) consacrées à « Documentation techniques – Techniques de documentation ».

Les communications viennent d’être publiées.

Pour tout renseignement : groupe.inccaf@gmail.com

 


Programme start: 2009

CICRP: Philippe Bromblet (director), Jérémie Berthonneau (doctoral student 2010–2012), Jean-Marc Vallet

Partnership(s): Bureau of Geological and Mining Research (BRGM), Center for Interdisciplinary Nanoscience of Marseille (CINaM) (Aix-Marseille University), PACA Regional Council

This project forms the topic of a thesis (Jérémie Berthonneau) cofinanced by the BRGM, the PACA Regional Council and the CICRP, focusing on the role of clays in the deterioration of stone, and more specifically on the spalling affecting monuments built from Burdigalian molasses in the region. Petrophysical, petrographic and mineralogical profiles as well as hydric and hygric dilation tests have been carried out on the full range of samples taken from approximately 30 quarries and a few monuments. Field visits have been carried out to evaluate the durability of the stones studied in the regional heritage. These investigations have shown that there is a relationship between the clay content, the amplitude of the dilations and the alterability of the molasse. Qualitative and quantitative analyses of clay minerals are in progress using different methodologies (DRX and MET/EDS) on approximately 10 of the more alterable and clay-rich facies to determine precisely the impact of swelling clay materials and their location in the material in the development of spalling.

Publications:

  • J. Berthonneau, ‘Relationships between internal properties and durability in the « Molasse du Midi » limestone (South-East of France)‘, Euromat Colloquium, Montpellier 2011, summary and communication
  • J. Berthonneau, O. Grauby, A. Baronnet, D. Dessandier, P. Bromblet and J.-M. Vallet, ‘Role of swelling clay minerals in the spalling decay mechanism of the « Molasse du Midi » limestone (South-east of France)’, 12th International Congress on the Deterioration and Conservation of Stone, 2012.

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.