A Bronze Age Pre â Historic DOLMEN : Laser Cleaning Techniques of Paintings and Graffiti. ( The BISCEGLIE DOLMEN case study ). Giuseppe Daurelio. 1.
La VERITA' su come fu IDEATA e TROVATA casualmente la Tecnica Daurelio n. 2 per il Laser Monumental Cleaning & Restoring
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The TRUTH 'about how it was DESIGNED and FOUND accidentally Daurelio Technique n. 2 for the Laser Monumental Cleaning & Restoring
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A Bronze Age Pre – Historic DOLMEN : Laser Cleaning Techniques of Paintings and Graffiti ( The BISCEGLIE DOLMEN case study )
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Giuseppe Daurelio 1 , Alessandro De Giacomo 2 and Francesca Radina 3 1 Centro Laser S.c. r. l. - Centro Ricerche , 70010 Valenzano ( Bari ) Italy 2 IMIP – CNR , sect.Bari, Via Orabona 4 , 70126 Bari , Italy 3 Ministero per i Beni e le Attività Culturali – Soprintendenza Archeologica per la Puglia – Bari , Italy
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Key-words: laser cleaning , art restoration , dolmen , graffiti, paintings, optical shock – wave
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1. Introduction This complex monument has been discovered at the beginning of this century and studied by M. GERVASO . Only the central gallery , constituted by two large vertical slabs, obtained from calcareous rocks remains of the whole structure . It represents the local geological emergence and ends in a rectangular plan “cell” with walls and covering built with analogous slabs .The whole building was included and covered by an elliptical plan tumulus as reported for other similar monuments situated in the same territory of BISCEGLIE and GIOVINAZZO ( in South of ITALY ) . The monument was built by a community established in that area to mark their territory. It has a typical funerary character ( funeral urn ) and it was destined to the collective sepulchre in the Middle Bronze Age, as indicated by the ceramics finds , accompanying the rich dead men, copper objects and ornaments, bones and amber recovered inside together with human rests. Because of its dislocations, in the open country far the centre of BISCEGLIE ( Bari – ITALY ) and its long and persisting exposition to atmospheric agents, numerous problems arise for its preservation and protection from the recent acts of vandalism . 2. Laser source for cleaning LASER Nd – YAG , portable , pulsed , N- Mode and Q – Switch , Repetition Rates 1 to 20 Hz , Pulse Width and Maximum Energy per pulse ( 150 s - 200 mJ a 0.53 m // 6 ns – 400 mJ a 1.06 m ) , Model PALLADIO , QUANTA SYSTEM , Milan , Italy
2. Laser Cleaning Techniques and Results
A Bronze Age Pre – Historic DOLMEN .......
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On the monument an accurate Degradation Mapping was carried out as a first stage of the works , so that the different types of Writings, Paintings and so on were evaluated and some previous Laser Cleaning Tests executed . Black Incrustations ( due to the Lighting the fires of wood branches by farmers for warming themselves during the winters ) , PAINTINGS ( by Sprayed Black Paint ) and WRITINGS ( by Marking Pen / Felt Pen / Ball Point Pen / Graphite Pencil and Text Liner Marking Pen ) were noted . The used Pens , utilizd Permanent / Fluorescent Ink Pigments in different colours ( Light Blue – Pink – Black – Green ) , producing on the calcareous stones diverse and large WRITING TRACES . Some previous cleaning works ( no by Laser ) , executed by Chemical Solvents , De-Painting Gels and Acids even if have no easily removed the Paintings and Writings had also produced for ever on the monument some visible damages ( Washing away and Dripping Traces ) . Degradation Mapping and Laser Cleaning with Photographs, during and after the process in – situ were carried out . In this Art Restoration Work two different portable Lasers were tested , according to the needs and the surface absorption of the laser beam wavelengths ( 1.06 and 10.6 micron) by the traces on the stone . A continuous , pulsed or super – pulsed CO2 laser beam as well as N-Mode , Q – Switch Mode , 1st and 2 nd harmonics ( 1.06 and 0.53 micron ) of a Nd – YAG laser were employed . At the end only the Q – Switch Mode ( 6 ns – f 1 to 20 Hz - E max 400 mJ per pulse ) at 1.06 micron was the suited and wined wavelength . BLACK INCRUSTATIONS and SPRAYED BLACK PAINTINGS were easily cleaned and removable by a defocused and Q – Switched Nd - YAG Laser Beam . On the opposite side the LASER ABLATION of the different WRITINGS resulted very difficult to evaporate even if a Q- Switched Laser Beam as defocused or focused one as by employing high values of repetition rate and pulse energy were tested . The usual thermal and / or shock – wave techniques did not produce some beneficial surface effects . The laser beam appeared to be fully reflected by these inks and pigments , especially in presence of fluorescent and / or permanent inks . It was also proved to dry the writings with deionised ( and no ) water to increase the optical coupling and absorption on the surface between the laser energy and the inks as well as furnishing a very thin layer of deionised water on the “ GRAFFITI “ during the laser surface processing , but the results were negative . So it was decided to stop the researches on the WRITINGS . But …….an accident or for lucky …….the Sky began to rain : The History
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In that moment the sky started to rain abundantly , it was suddenly necessary to cover and protect the portable lasers (CO2 and Nd – YAG sources ) as they were in “ open country “ . It was so that “ I put a my foot into a puddle “ and a my shoe was wetted and splashed with mud …….. a mud ……..coloured chestnut - maroon . I tried to remove this mud by my shoe and it was so that a WINNING IDEA comes in my brain . This earth and mud was clayey and rich of Fe and Al oxides …….and these oxides absorb much more the infrared radiations ( so I had studied and experimented in 24 years on Laser Material Processing into Labs. ) ; so I may use this wetted mud as a coating ( a very thin layer ) on the WRITINGS and hope that they absorb laser energy and transfer it to the bulk material ( writings on the stone ) , enhancing the shock – wave process by laser . I waited that the rain stopped and …… suddenly tested this possible IDEA , make mud dirty by my hands the writings and ……………tried ……..O.K. it was a Goal !
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A Bronze Age Pre – Historic DOLMEN .......
The final result was very exciting as the whole DOLMEN was fully cleaned by different LASER TECHNIQUES without no visible surface damages .
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************** Albert EISTEIN diceva : La fortuna non esiste ma esiste il caso, ed è il caso che premia le menti preparate . Ed io ( G. Daurelio ) , che sono nulla al confronto di A. Einstein , sono daccordo in pieno Quanto sopra , appena riportato nel testo, ne fu una prova tangibile . Ma ....................the Referees di questo Lavoro mi dissero che NON SI POTEVA SCRIVERE questo avvenimento e .............così dovetti cambiare qualcosa sul Paper . La VERITA' su come fu IDEATA e TROVATA casualmente la Tecnica Daurelio n. 2
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Albert EISTEIN said: Luck does not exist but there is the case, and it is the case that rewards the prepared mind. And I (G. Daurelio), that I am nothing compared to A. Einstein, I agree in full. As stated in the text just above it was a tangible proof. But the referees of this Paper .................... told me that it COULD NOT WRITE this event and so ............. I had to change something on Paper.
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The TRUTH 'about how it was DESIGNED and FOUND accidentally Technical Daurelio n. 2
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A Bronze Age Pre – Historic DOLMEN .......
