Since a few decades, the research laboratories of the big Museums realize systematically a scientific analysis of their objects often on the occasion of exhibitions(exposures) or in the process of acquisition of new works. At the same time, the searches(researches) concerning process techniques, origin and ageing of furniture, paintings(boards) and works of art developed, creating plentiful one documentary resource. So, the scientific analysis became in a few years for the experts the counterpart of the stylistic approach, the process techniques, the characteristics of one or several constituent materials as well as their states of natural or artificial ageing, allowing to confirm a doubt, to specify an identification or to assure (insure) an authentification. The made analyses have for objectives to bring, according to the same analytical processes as the research laboratories of Museums, all the elements necessary for the authentification. The used materials, their change, the process techniques of objects, artistic context and history of creation, all these elements are appropriate(peculiar) to a culture, in a time(period), in artistic techniques, sometimes to an artist. The role of this complementary(additional) scientific study is then to find, when they are present, these guarantors(guarantees) of age(seniority) and authenticity. For that purpose, the Office of expertise Stéphane PEPE proposes five complementary(additional) scientific approaches.
The methods chosen as analyses are a function of cases and of the degree of necessary precision. Every study being unique, we work in close collaboration with our customers to answer at best their questions. Specialists team in all the domains is at your disposal. To benefit from their advice, confidential and free, please contact the department of the scientific analyses.
Principle: A steam light source of mercury, which emits(utters) an UV brilliance(radiation), causes(provokes) phenomena of fluorescence in the visible opacity (lamp of Wood)..
Applications : The ultraviolet brilliance(radiation) allows to locate(localize) the heterogeneousness of the lit(enlightened) surface and reveals the various recent interventions to the surface of a picture(board). The fluorescence ultraviolet is very used in the analysis of paints(paintings), but also for varnishs in cabinetmaking(cabinetwork), and all the occasions of surfaces.
Principle : Certain substances are transparent in the infrared brilliance. This brilliance allows to explore the underlying layers in the skin of certain materials and the fine pictorial layers.
Applications : Reading of marks(brands) and registrations(inscriptions) erased on paper, parchment, ceramic, wood, stone, paint(painting) and painting(cloth). Highlighting of preparatory drawings, indications of putting in color, hidden signatures, repentirs under, or in, the pictorial coats(layers).
Principle : The low wavelength of the X-rays conditions their penetration. The absorption depends at the same time on the nature of materials, their volume, their density and atomic number. The X-rays which crossed the object are detected by digital sensors today.
Applications : Paint(Painting): pictorial Technique (sketch, repentirs, change of composition, overloads, surpeints). State of preservation of the support (medium) and the pictorial coat(layer). Identification of the various parts(parties) of an object. Process techniques
Principle : The X-rays cross the volume which is subjected(submitted) to them by losing of their intensity according to the met resistances. A X-ray tube revolves around the object and produces moved closer cups(cuttings) (over lap) or distant. The reconstituted image allows to visualize(display) by successive cups(cuttings) the volume examined in three dimensions(size).
Applications : Metallic objects, wood, plastic (plastic art), except glass. Internal observations very located(localized) in the space. Reconstruction of disappeared parts(parties) or to remove(kidnap). Non-destructive internal look which allows, among others, to discover patches and not visible assemblies from the outside..
Principle : Stereoscopic view(sight) keeping(preserving) the relief with swellings from 1 to 1000. The lighting is often external, directional with optical fibers
Applications : Observation of surfaces, patina, strata of the pictorial coats(layers) of polychromatic wood, murals and easel paintings, etc.
Principle : The electronic microscopy rests(bases) on the same principle as the optical microscopy, in the difference near that the incidental beam(shelf) is established(constituted) by an electron beam instead of a visible ray of light. The Electronic Microscopy with Sweeping(Scanning) (MEB) allows to obtain a reflected image (enlarged until 100 000 times or more) from the sample, highlighting details (” as the effect depth “) impossibles to be otherwise(differently) revealed. The technique of examination of the MEB serves for the study of the solid materials. The preparation of the sample consists in returning this one a driver (if he(it) is not him(it) already) by using a matrix with carbon and with golden coats(layers) – palladium and includes vari-ntes according to materials and the end(purpose) of the analysis. Electronic microanalysis by X-ray (MEB + microsound EDS) This tool is of a big utility for the study of surfaces; it is a question of the ” microprobe with X-rays ” installed(settled) on the MEB. She(It) consists of a system where the limited(punctual) beam of electrons sent on the sample generates X-rays of fluorescence. This device(plan) allows the chemical microanalysis of the material the reliability of which is exceptional.