AbstractAn Italian university department has defined methodologies for the application of innovative laser technologies to the restoration of different artistic finds: stone, wood, ceramic, metal. The department wants to make available its know-how, expertise and solutions to companies, research organisations and institutions involved in artworks conservation. It is interested in technical cooperation or manufacturing agreements.
DetailsIn the conservative restoration of Cultural Heritage, cleaning is a difficult and irreversible operation, representing the moment of interaction with the treated surface that can modify its equilibrium. It is an intervention oriented to recovering the artwork’s readability.
Laser techniques allow preventing surface from being damaged, unlike all the existing cleaning methods (methods with the use of water only, mechanical methods and chemical methods), which have negative collateral effects.
In fact, the absorption of laser radiation depends on the peculiar optical properties of the treated materials, which can be used to control the laser cleaning effects, making cleaning highly selective.
An Italian university department has developed methodologies to assess the application of laser technologies to the restoration of different artistic finds: stone, wood, ceramic, metal. They allow identifying the optimal parameters for laser radiation to safely remove degradation layers from artworks.
Particularly, for stone materials the researchers have characterised the optimal laser parameters and the procedures to remove graffiti (coloured synthetic systems, the purpose whereof is to be visible (bright, fluorescent and therefore highly reflective) and especially indelible) for 8 different calcareous substrates (Carrara marble, Trani stone, Biancone, Travertine, Chianca, Yellow sandstone, White sandstone, Leccese tufa) and 12 diverse spray paintings (3 typologies: metallic, fluorescent and pastel).
The laser cleaning methodology developed has a great interest at international level because of the many problems related to the removal of graffiti without causing any damage to the substrate. The study has covered different Apulian stone substrates and multiple types of spray dyes. It has been carried out by the use of different Nd:YAG laser systems: Short Free Running (t = 40µs ÷ 100µs), Q-Switch (t=8ns) and Normal Mode (t=120µs, 300µs and 500µs).
In the field of metallic artworks, innovative laser technologies based on the use of three Nd:YAG laser sources have been successfully applied at the Diocesan Museum of Bisceglie (BA) for micro laser-welding, cleaning and classification by laser marking of precious metallic finds.
The main innovation is in the possibility of using laser radiations of different wavelengths, power and pulse width for the Restoring of Cultural Heritage, which allows the advantages described next.
These advantages derive from the physical principles of the interaction between the electromagnetic radiation and the surface, therefore not obtainable by active chemical actions or mechanical abrasive actions.
- Minimum invasivity: it isn't necessary to use chemical products and abrasive materials. That allows treating extremely fragile structures in advanced alteration state. In these cases cleaning can be carried out before the consolidation.
- High control level: the removal of the deterioration layer takes place progressively, involving a few micron thicknesses per impulse. The operator controls directly the laser action and he/she can interrupt the cleaning at whichever level.
- High precision: the cleaning process involves only the area that is illuminated by the laser; this area can be made small as one wishes. The use of optical fibres for the transmission of the laser radiation allows furthermore to treat also complex surfaces;
- Selectivity: the absorption of laser radiation depends on the peculiar optical properties of materials, so it can be used to control laser cleaning. For example, in the case of black crusts, by proper selection of the radiation parameters, the removal of alteration layer stops automatically when the brighter substrate, characterised by different optical properties, comes to light.