In order to study a cultural object, restorers and conservators can carry out non-invasive analyses using scientific techniques that will allow a better understanding of the structural elements of the object. Laboratories are equipped to carry out in-depth research on works and cultural objects. Thus, several scientific techniques are available to us.I
Infrared Radiography
Infrared reflectography makes it possible to detect restorations that are not necessarily detectable by UV because they are too old. It also allows us to see preparatory drawings, hidden inscriptions, and compositional modifications. The infrared reflectography camera is very interesting because the result of the observation is immediately visible on the video screen, which is not the case when it comes to photography. But reflectography remains in the upper layers of the work. I work with Jean-Gabriel Aubert, radiographer/photographer at Arc’Antique in Nantes. X-ray radiography, a non-destructive technique, reveals the details: shape, structure, decorations, manufacturing technique, old restoration and the state of conservation. https://grand-patrimoine.loire-atlantique.fr/jcms/les-services/arc-antique/laboratoire-arc-antique-fr-p2_145023
Ultraviolet Radiography
Ultraviolet rays make it possible to detect relatively recent restorations, which for a restorer, can represent more than a century. Under the effect of UV radiation, the restorations appear as opaque spots.
This example consists of making visible the surface repaints, present on top of the varnish. The lighting used for this purpose is provided by two black light ramps. It excites the fluorescence of the materials constituting the varnish, thus making the repainted areas appear as opaque spots.
X-ray Radiography
This technique makes it possible to go even further and study all the layers of the work. Radiography records the image formed by X-rays which are more or less absorbed when they pass through an object. We thus obtain both a representation of the internal constitution (structure, frames, assemblies, etc.) and of the epidermis of the paintings or objects studied (gaps in old polychromy subsequently covered, superimposed compositions, etc.)
Low Pressure Heated Table
Equipped with a plate with adjustable heat (thermostatic regulation) and a low pressure suction system (homogeneous and regular) with a dimmer, the table is used for the restoration of the canvas support of painted works (treatment of deformations, synthetic or traditional linings) as well as for the reattachment of the various constituent layers (preparation layer, pictorial layer) thanks to the control of the penetration of the adhesives.
I was able to meet Professor Chauvet from the University of Nantes to carry out tests on paintings using a multispectral camera. We were able to observe underlying layers, lines and preparatory sketches.
More info and sources:
www.culture.gouv.fr/culture/conservation/fr/methodes/http://www.culture.gouv.fr/culture/conservation/fr/methodes/rif.htm
http://www.arcantique.org