Measurements on the facade of the Cathedral of Huesca, ES.
1. Scanning IR-colour reflectography - [INOA]
EQUIPMENT: The equipment allows recording colour and IR reflected images free of optical distortion and with the best resolution presently available in the field. The system collects simultaneously images corresponding to four different regions of the electromagnetic spectrum, infrared, red, green and blue, which can be perfectly superimposed. From the collected data it is possible compare directly, on the monitor of a PC, the visible image of the object under study and its IR reflectogram. This allows users to study the execution technique of a painter and, as in a recent study of Perugino's technique, clearly identify hand-drawings, pentimenti, and cartoon re-use. Besides, it is also possible to identify regions of undocumented restorations or the presence of some pigments. For this purpose, the imaging survey can be usefully complemented with punctual spectral analyses carried out by fiber optic vis-NIR spectroscopy.
USE: characterisation of painting techniques, in panel and wall paintings, through the identification of underdrawings; identification of undocumented interventions; characterisation of pigments.
2. Laser micro-profilometry - [INOA]
EQUIPMENT: The laser micro-profilometer is an interferometric device to measure with high precision the distance between an optical head and the surface of a wide variety of objects. The optical head is a conoprobe, a device composed by a birifrangent crystal coupled to two polarizers, placed between a lens and a CCD camera. The light, diffused by the object under investigation, is split into two beams which interfere creating a fringe pattern. The distance comes from the measurement of the fringe period. Depending on the lens mounted on the probe, a micrometric to sub-micrometric resolution is achievable, to the detriment of a short measurement range. Such a distance-meter, mounted on a scanning device, allows the relief of small objects or almost flat surfaces to be measured with very fine details.
USE: Laser micro-profilometry can be applied to measure and monitor the surface of many artworks, ranging from wooden panels to characterise possible undocumented restoration interventions, to any painting to evidentiate micro colour detachments; to marble artefacts to monitor the roughness before and after the restoration intervention, to panel paintings of doubtful attribution to find out drawing technique.
3.Fiber optics FT-IR - [UNI-PG]
EQUIPMENT: The critical part of the portable FT-IR spectrometer is the probe, made by chalcogenide glass fibers. The fibers totally absorb radiations below 900 cm-1, but the region 5000-900 cm-1 is characterised by a satisfactory signal/noise ratio. This is the "finger print" region for the identification of many organic polymeric substances and inorganic salts. A light and manageable equipment combines IR transparent fiber optics with a compact portable JASCO interferometer, that can be used even on the scaffold of a restoration yard. A large number of laboratory-prepared standards allow UNI-PG to optimally use the technique.
USE: in-situ non-destructive identification of alterations on stones, mortars and metals, identification of pigments and binders in paintings; identification of undocumented restorations. The technique is complementary to micro-Raman and X-ray fluorescence.
4. Micro-Raman spectroscopy - [UNI-PG]
EQUIPMENT: A portable equipment for in situ non-destructive studies of inorganic and some organic substances on stones, metals or polychrome surfaces is available. A large collection of standards and specific expertise are also available.
USE: in-situ non-destructive identification of alterations on stones, mortars and metals; identification of pigments in wall paintings. This technique is complementary to FT-IR and X-ray fluorescence.
5. X-ray fluorescence - [UNI-PG]
EQUIPMENT: This instrument has a resolution of ~130 eV which is the best presently available for portable equipments. At UNI-PG the instrument is available coupled with a specific expertise in inorganic sample identification.
USE: The instrument can be used for elemental analyses (elements wth Z>12 ) on stones, metals, wall and easel paintings, and other objects. This technique is complementary to FT-IR and micro-Raman spectroscopies.
6. Fiber optics VIS-NIR spectroscopy - [UNI-PG]
EQUIPMENT: A portable instrument is available to be used as spectrometer and colorimeter.
USE: Colorimetric measurements and, possibly, identification of pigments. Measurement of possible colour changing after restoration.
7. Fiber optics UV-VIS fluorescence - [UNI-PG]
EQUIPMENT: A portable equipment for in situ non-destructive studies of organic substances on polychrome surfaces is available.
USE: in-situ non-destructive identification of the presence of organic substances and possibly of their nature. The technique is useful as a first approach to the study of organic substances and could be also useful to guide micro-samplings for chromatographic or stratigraphic studies.
8.Portable fluorescence system - [OPD]
EQUIPMENT: fluorescence is recorded by a couple of lamps (Lubino model) with a max emission at 365nm. New lamps are also available with additional filters to furtherly cut the visible component. As a reference to evaluate the quality of the image a reflectance spectralon is used. Images are recorded by a digital Nikon or CCD camera.
USE: in-situ identification of distribution of organic substances, via images.
9. EUREKA-Mouse? - [UNI-PG]
EQUIPMENT: The portable instrument (Nuclear Magnetic Resonance mobile universal surface explorer, registered trademark at the University of Aachen -Eureka project E!2214-MOUSE.) is a unidirectional NMR relaxometer purposely created for the study of cultural heritage and for NMR characterisation of unmovable objects. At present, the easily portable EUREKA-MOUSE?, belonging to UNI-PG, is equipped with a Bruker Minispec console and a laptop computer. Probeheads are small, inserted within the magnet and already pretuned (Bruker Biospin?).
USE: The instrument can be used to measure paper or parchment degradation, wood degradation, detachment of painted surfaces from a wall or other support, and presence of water in porous stones, frescoes or ceramics.
10. Drilling Resistance Measurement System - [CNR-ICVBC]
EQUIPMENT: DRMS is a new portable system developed and validated for directly determining stone mechanical features such as the "hardness" by measuring its drilling resistance [validated within the European project HARDROCK:Development of a new measurement method to determine the superficial hardness of exposed monumental rocks (SM&T,CT96-2065)].
The force is measured with a monaxial load cell (estensimetric transducer) which transform the gauge deformation into an electrical signal (tension). The load cell deformation is correlated with the "resistance to penetration" hence to the "stone cohesion". The measuring unit of the Drilling Resistance (DR) is Kgf (Newton) with sensitivity of 2.0115E-0,3 (V/V) corresponding at 1 N and has 100 N as maximum load. The DRMS has not competitors for its application in comparative tests "in situ" and it has been suggested as standard method, to UNI Normal (Italy), for assess the quality assurance of consolidating treatments.
USE: The test is essentially non-destructive, since stones can be tested, with only minor patching of holes (ؠ5 mm) on exposed faces. With this system it resulted possible to determine the cohesion profile of a stone material based on affordable and sensible data of its mechanical and abrasive properties. With this tool it is possible to determine either the state of decay and the consolidating performance (efficiency and depth of penetration) of applied conservative treatments.