CNEP, a center of technical assistance to cultural backgrounds.

The research activity on the long-term behavior of organic materials used for the development, restoration and preventive conservation of works of art involves three levels of intervention:

– An analysis of organic materials in their original state;

– An Application of physicochemical constraints causing, in the long term, either photoageings (under various light distributions) or thermalageings (at different temperatures), hydrolytic ageing either of these organic materials;

– An analysis of the chemical evolution during the ageing, and polymer matrices of all fillers, additives, pigments, soluble dyes, … that give the mixture properties of the finished material. This analysis helps streamline the complex physical and chemical phenomena observed during aging and exploit them to predict lifetimes of these materials under conditions of use.

The analysis of organic matter in the solid state is a key concern of CNEP, which implements in particular the following techniques:

1 – Infra Red spectroscopy Fourier Transform Infrared (FTIR), possibly with photoacoustic detection (for very opaque systems), analysis of the first microns of a surface (ATR-Thunderdome or more recently ATR imaging);

2 – FTIR microspectrophotometry (coupling the first technique and IR microscopy);

3 – spectrophotometry molecular Raman scattering;

4 – microspectrophotometry molecular Raman scattering;

5 – spectrophotometry UV-visible absorption achieved with devices equipped with an integrating sphere;

6 – microspectrofluorometry.

The microspectrophotométries and the microspectrofluorometry are applied either to elementary layers 7 microns, or micro-zones from 9 to 1000 μm² section.

These techniques are well suited to the analysis of samples of artwork.

Preliminary to any development work, restoration or preventive conservation of works of art approach, it is for example possible to analyze:

– The nature of most of the organic substances involved in varnishes and paints in all media: these binders may be adhesives, waxes, oils, lacquers or synthetic polymers. Photomicrography examines the stratigraphy and each individual layer is then analyzed by FTIR and Raman molecular microprobe;

– The nature of a large number of fillers, pigments or dyes;

– The nature of the adhesives, consolidants … used in a previous restoration;

– The state of aging or organic binders from the original products anterior restoration;

– The nature and state of aging of textile fibers and possibly their sizing;

– The aging condition of old papers;

– The nature and state of aging old rubbers;

– The nature and the state of development in terms of conservation of audiovisual media (except photographic film);

– The nature and state of aging consolidant organic compounds and water-repellent stones; these compounds can be directly analyzed on stony surface and in the most superficial by FTIR spectrophotometry with photoacoustic detection layers;

– The nature and state of aging of varnishes, paints or organic coatings on metal surfaces; analysis can also involve adhesion primers.

Study examples:

– Paints the Grand Foyer of the Opera Garnier Paul Baudry, Felix Barrias Jules-Elie Delaunay (1874)

– Murals of Notre Dame des Doms in Avignon

– Painted decorations of the former Hospice Gartois Lille

– Polychromies carriages and sleighs historical museum of Versailles Carosses

– Chinese polychrome sculptures

– Enforcement agents consolidation of the stone for the restoration of the Tour Saint-Jacques

– paints of the time or the workshop of Leonardo da Vinci and Rembrandt

– Pictures galleries or private owners suspected J. Arp, F. Leger, Modigliani, Soutine, Van Gogh, Monet

– Contribution to the authentication of works from private owners