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Portail > Offres > Offre USR3224-WITNOW-001 - Emploi contractuel post-doctoral (H/F) : Etude de la déformation et restauration de peintures murales sur enduits en plâtre

Post-doctoral contract position (M/F): Study of the deformation and restoration of wall paintings on plaster

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : vendredi 22 octobre 2021

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General information

Reference : USR3224-WITNOW-001
Workplace : PARIS 05
Date of publication : Friday, October 1, 2021
Type of Contract : FTC Scientist
Contract Period : 18 months
Expected date of employment : 1 January 2022
Proportion of work : Full time
Remuneration : between 2743 € and 3896 € gross per month depending on experience
Desired level of education : PhD
Experience required : 1 to 4 years

Missions

The person recruited will finely characterise the composition of painted plaster from wall paintings on a site intended for restoration, will be responsible for setting up and carrying out a study of the microscopic structure, mass transfer and mechanical properties of thin layers of plaster samples, and will propose a levelling methodology that can be adapted on site. For this, it will test and refine the protocol on the basis of in situ application experiments.
The plaster layers used as a support for the paint are often laid on a thin (a few millimetres) levelling layer of the masonry. In such systems, the preservation of the wall paintings is highly dependent on the natural sensitivity of the plaster, which then suffers damage that must be detected as soon as possible or treated with suitable procedures. The damage is in the form of detachment and lifting of fragments of painted plaster. The deformations of these plasters are not elastic and the current methods of consolidating the plasters are not well adapted, often leading to breakage.
The aim of the project is to develop and make reliable a methodology based on mechanical softening by controlled mass transfer (hydric and/or hygric) within solid mixtures based on calcium sulphate and to exploit the reversibility of the deformation process. Controlling the wetting of the plaster, while securing the paint layers, should allow the plaster to be smoothed and consolidated without causing breakage and avoiding structural changes in the plaster layer as much as possible.
The plaster layers used as a support for the paint are often laid on a thin (a few millimetres) levelling layer of the masonry. In such systems, the preservation of the wall paintings is highly dependent on the natural sensitivity of the plaster, which then suffers damage that must be detected as soon as possible or treated with suitable methods. The damage is in the form of detachment and lifting of fragments of painted plaster. The deformations of these plasters are not elastic and the current methods of consolidating the plasters are not well adapted, often leading to breakage.
The aim of the project is to develop and make reliable a methodology based on mechanical softening by controlled mass transfer (hydric and/or hygric) within solid mixtures based on calcium sulphate and to exploit the reversibility of the deformation process. Controlling the wetting of the plaster, while securing the paint layers, should allow the plaster to be smoothed and consolidated without causing breakage and avoiding structural changes in the plaster layer as much as possible.

Activities

1. Material identification. In-depth compositional analysis (SEM-EDS, TEM, μ-Raman, FTIR, XRD) of existing paint coatings on a real site
2. Deformation analysis.
- 2.1. Deformation tests under uniform absorption condition in controlled environment (temperature and relative humidity).
- 2.2. Wetting deformation tests to simulate the effect of controlled capillary rise.
- 2.3 Wetting deformation tests under steam field.
For the three variants, it will be necessary to establish the deformation kinetics of the test bodies, to compare the efficiency of the methods with each other, to test the influence of variations in the pore distribution and to test the influence of mechanical loads for different characteristic dimensions of the test bodies.
The kinetics of ad-/absorption will be followed by imaging techniques such as THz. The nucleation/recrystallisation processes will be followed by SEM, TEM, μ-Raman, FTIR, XRD and mechanical strength measurements.
3. Analysis and characterisation of the reversibility of the deformed objects in the laboratory. In particular, the development of a re-flattening process will be studied with the objective of in situ transfer.
4. In situ transfer.
- 4.1. The extent of the deformations before and after the intervention will be monitored physically (3D scan) and the composition identified by prior physico-chemical analyses (see point 1 above).
- 4.2. The deployment of the method in situ (application by a wall painting restorer).

Translated with www.DeepL.com/Translator (free version)

Skills

PhD. thesis in materials science, focusing on the micro-, meso- and macroscopic properties of solid mineral materials. In particular, the candidate should be familiar with material behaviour, stress deformation, crystallography and mineral chemistry. Knowledge of spectroscopic characterisation methods of mineral and crystalline materials, mechanical characterisation, or at least some of these methods, will be essential.
The person recruited should be interested in the subject, versatile (design, performance of experiments and interpretation of results at the crossroads of different scientific fields), open (easy to learn new techniques), inventive (proposals for variations on generic protocols) and autonomous. She/he should also have a taste for experimental work and a facility for contact.
A regular practice of English will be an important asset.

Translated with www.DeepL.com/Translator (free version)

Work Context

The job will take place mainly at LRMH in Champs sur Marne, with stays in the partner laboratories (IMPMC, Paris and LPPI, Neuville), as well as on the painting site in Haudiomont (Meuse).
The LRMH will bring to the project its knowledge of wall paintings, of plaster as a finishing material, of the hydric and thermal behaviour of materials, as well as diagnostic skills (3D scan, stimulated IR thermography, THz), analytical skills (SEM-EDS, analysis of soluble salts) and part of the experimental infrastructure (humidity-controlled chambers, laboratories for the preparation of test specimens, etc.)
The Institute of Mineralogy, Physics of Materials and Cosmochemistry (IMPMC) is composed of 11 teams, including the PALM team (Properties of Amorphous, Liquid and Minerals), which includes 11 permanent staff (CNRS, Sorbonne University, IRD and Muséum National d'Histoire Naturelle) working on several themes in the field of heritage: stained glass, glazes and gems. The team has international expertise in the structure of amorphous materials, minerals and colour-property relationships. The IMPMC will bring to the project its expertise in mineralogy, necessary to understand the nucleation/recrystallization processes in plaster.
The Laboratoire de Physicochimie des Polymères et des Interfaces (LPPI) at CY Cergy Paris Université develops and characterises polymeric or hybrid materials for specific applications. One of these research areas concerns materials for heritage. The IMAT platform bringing together a multitude of characterisation techniques, particularly in microscopy (TEM (coupled Raman), AFM, confocal) will be accessible to the person recruited.
The study missions on the wall paintings in situ at Haudiomont (Meuse) will be co-supervised by the Meuse heritage and museum conservation and development department, which will provide its knowledge of the artist's work, administrative and logistical support, as well as by a wall painting restorer, a graduate of the INP, who will provide knowledge of the cases and optimise the selected protocols in the field, resulting from the laboratory experiments.

Constraints and risks

Travels
Some works to be carried out on scaffolding

Additional Information

Candidates with less than 2 years experience are encouraged to apply

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