Il convegno APLAR, tenutosi a Firenze nel settembre 2017, è stato anche l’occasione di celebrare degnamente gli ultimi 20 anni, che in questa città hanno visto nascere e svilupparsi una collaborazione intensa, fruttuosa ed appassionante fra i centri di ricerca, i centri di restauro, le aziende di restauro e quelle di tecnologia laser del territorio, finalizzata alla sperimentazione delle nuove tecnologie laser per lo studio e la conservazione di opere d’arte. Firenze non è certamente il primo o l’unico luogo dove questi studi sono stati condotti fino all’applicazione su capolavori di inestimabile valore, ma desidero sottolineare, sulla base della mia esperienza personale, che la multidisciplinarità dei gruppi di lavoro ha rappresentato uno dei fattori principali che hanno portato alla messa a punto di procedure risolutive in problemi di conservazione anche estremamente complessi.
Venendo al presente, il convegno APLAR testimonia assai bene il livello di maturità attualmente raggiunto nelle applicazioni delle tecniche laser alla conservazione. Sono molti gli aspetti che sottolineano gli avanzamenti dei metodi e delle conoscenze, e che tendono alla standardizzazione degli approcci, su cui la maggior parte degli operatori della conservazione hanno sviluppato una visione comune. A partire dagli studi modellistici su campioni rappresentativi, necessari per investigare il tipo di interazione laser su materiali non ancora testati o in condizioni di impiego particolarmente complesse, fino agli studi preliminari su porzioni limitate dell’opera d’arte, indispensabili per la discriminazione delle soglie di danneggiamento e quindi per la definizione di parametri operativi dell’intervento laser.
Anche dal punto di vista della scelta delle apparecchiature laser da impiegare si sta procedendo verso criteri di standardizzazione: si registra sempre meno la tendenza tipica dei primi studi pioneristici, in cui si impiegava il primo (e spesso l’unico) laser a disposizione, insieme alla voglia di promuoverlo su tutti i tipi di materiali. Anzi, dalle comunicazioni risulta una visione ricorrente, e quindi condivisa, che per certi materiali si utilizzino certi tipi di laser e con determinate modalità di emissione.
Da moltissimi studi emerge chiaramente che, insieme alla scelta della lunghezza d’onda della luce laser che determina il maggiore o minore assorbimento ottico in funzione del materiale trattato, anche la durata dell’impulso viene considerata un parametro cruciale per controllare il tipo di interazione laser-materiale e gli effetti conseguenti. è diventato patrimonio di esperienza comune che gli impulsi laser “lunghi”, cioè nel regime del millisecondi, sviluppino un’azione primariamente di tipo termico, mentre impulsi più brevi, dai microsecondi ai nanosecondi, siano in grado di ridurre il danno termico e produrre un’azione meccanica, che va comunque controllata per indurre effetti positivi, come ablazione puntuale o spallazione di incrostazioni superficiali, o per evitare effetti negativi, come danni di tipo fotomeccanico che possono causare la microframmentazione delle superfici.
E’ inoltre molto significativo (particolarmente per chi come me è da molti anni docente di interazione laser-materiali) che la maggior parte degli studi riportino il “range” operativo di emissione laser in termini di energia per unità di superficie (J/cm2), che è uno dei principali parametri per il confronto fra le diverse condizioni applicative e per trasmettere l’informazione ad altri operatori che vorranno applicare quelle tecniche in condizioni simili.
Identità di visione si riscontra anche sul fatto che la pulitura sia quasi sempre la combinazione di più tecniche. In molti casi infatti è opportuno far precedere trattamenti preliminari con tecniche di tipo meccanico e/o chimico, in modo da rimuovere efficientemente e con minor consumo di tempo le incrostazioni più spesse, e quindi operare in modo fine e controllato sulle superfici originali dell’opera con tecnica laser. Oltre alle applicazioni laser combinate con le altre tecniche di pulitura, nelle comunicazioni del convegno si riportano interessanti studi in cui il laser si associa all’impiego di sostanze e materiali (agar, alcol, vetrini, ecc.) frapposti fra la sorgente e la superficie da trattare, con lo scopo di mediare l’assorbimento della luce o proteggere da effetti collaterali indesiderati, come la ricaduta di particolato vaporizzato o l’eccessivo surriscaldamento locale. In alcuni casi il laser è impiegato da solo come scelta elettiva per risolvere condizioni di conservazione particolarmente critiche del manufatto artistico: materiali fragili, superfici complesse o microfratturate, distacchi di pellicole pittoriche, materiali che non tollerano umidità (nel qual caso di utilizza il cosiddetto “dry clean”).
Per quanto riguarda i materiali oggetto di pulitura laser, senza voler entrare nel dettaglio dal momento che il programma del convegno segue già questa classificazione, è possibile osservare che vi siano procedure oramai consolidate, in termini di scelta del laser e delle condizioni di trattamento, nei casi di materiali lapidei, stucchi, dipinti murali, vernici pittoriche, filati metallici e dorature, mentre per altri materiali il quadro applicativo è ancora oggetto di approfondimento e sperimentazione. A questo riguardo, di particolare interesse è l’approccio al restauro di opere moderne, caratterizzate da grande varietà nella composizione materica, per le quali la domanda di tecniche di pulitura laser potrebbe registrare una crescita notevole nei prossimi anni.
Il laser comunque non rappresenta solo uno strumento utile per la pulitura: la luce coerente può essere infatti impiegata come sonda per l’analisi dei materiali (tramite ad esempio spettroscopia LIBS o Raman) o per la scansione delle superfici di oggetti, allo scopo di fornirne la ricostruzione digitale 3D per applicazioni documentali, come testimoniato da alcuni lavori presentati al convegno.
Infine, vorrei concludere guardando al futuro con un libero esercizio di fantasia per immaginare cosa aspettarci dalle nuove tecnologie che potrebbero essere sviluppate, proprio partendo dagli impieghi della luce laser come strumento intelligente e portatore di una grande quantità di informazioni. Potremmo immaginare scenari futuri nel restauro laser, in analogia agli sviluppi che si vanno delineando in altri campi applicativi di impiego del laser, come quello medico e quello delle produzioni industriali, in cui la gran quantità di dati informativi (Big Data) che la luce genera durante le interazioni con i materiali viene raccolta con sensori o tecniche di diagnostica per immagini ed elaborata con metodi di intelligenza artificiale per aumentare il controllo, l’efficienza e la sicurezza dei trattamenti. Ad esempio, in campo chirurgico si sviluppano già metodi di “teranostica”, cioè di diagnostica eseguita in contemporanea alla terapia, che permettono di indirizzare l’azione del chirurgo nelle situazioni più complesse.
Non si tratterà quindi di sfruttare la gran mole di dati analitici prodotti in tempo reale allo scopo di andare verso l’automazione dei processi, ricadendo nell’errore prospettico che fecero alcuni tecnologi ai primordi dell’impiego del laser nel restauro, quanto piuttosto per fornire al restauratore nuovi strumenti che accrescano il suo livello di conoscenza, di controllo e di adattabilità delle procedure alla grande variabilità delle morfologie, della composizione materica e dello stato di degrado dei manufatti da sottoporre al trattamento conservativo.
Roberto Pini
Direttore Istituto di Fisica Applicata “Nello Carrara” - Consiglio Nazionale delle Ricerche Chiudi

Mi è avvenuto recentemente di ritornare sulle vicende del restauro della leggenda della Vera Croce dipinta da Piero della Francesca sulle pareti absidali di san Francesco in Arezzo, eseguito dall’Opificio insieme con la Soprintendenza locale negli anni Novanta dello scorso secolo; e di domandarmi, e di domandare a due persone della statura professionale del chimico Mauro Matteini e del restauratore Sabino Giovannoni, quali differenze tecniche o metodologiche avremmo potuto introdurre nei nostri lavori se quel restauro venisse effettuato al giorno d’oggi. Fra le altre, ci siamo chiesti, naturalmente, se un impiego delle tecnologie laser avrebbe potuto dimostrarsi utile in un caso così difficile per mille ragioni (che non elenco qui) come il ciclo pierfrancescano; e indipendentemente dalla risposta che ciascuno avrà ritenuto di proporre, quel che conta è che avremmo oggi più e meglio saputo che il laser era lì, per così dire accanto a noi, pronto a offrire il suo utilizzo; avremmo dato per scontate la sua presenza e la sua assistenza.
Ciò che intendo dire è che esiste ormai una consapevolezza assolutamente diffusa dell’esistenza del laser come strumento presente e attivo nella conservazione dei beni culturali; naturalmente confermato tale a seguito delle tante, sempre più numerose esperienze già maturate, delle quali APLAR, nelle sue successive edizioni, si è fatta così efficacemente testimone e divulgatrice.
Diamo oggi per conosciuto che non esista un solo laser nel restauro, cioè un’unica macchina tuttofare, ma che la ricerca fisica tradotta nel mercato offra oggi un range esteso di strumentazioni che funzionano secondo le declinazioni diverse di uno stesso principio, ognuna delle quali può risultare risolutiva in quella particolare situazione.
Una delle applicazioni più decisive ai fini di un risultato ottimale, è la scopertura di decorazioni murali sotto una scialbatura, e qui davvero i risultati ottenuti da Anna Brunetto ad Aosta, a Venezia, a Siena, e di lì in poi dagli altri autori come illustrato anche in questi Atti, inducono a rimpiangere amaramente quanto si è perso ad esempio, nel recupero dallo scialbo dei dipinti murali di Giotto in Santa Croce a Firenze, effettuato a metà Ottocento, quando le pareti delle Cappelle Peruzzi e Bardi sono state maltrattate a tale scopo con arnesi metallici (raschietti di varia conformazione) o al meglio con sostanze adesive adatte a una successiva azione di strappo; come del resto si è operato fino a tempi recentissimi.
Ancora: un altro aspetto che riguarda le funzioni applicative del laser consiste nel raggiunto discernimento che esso non risulta una cura miracolosa per situazioni disperate, quanto uno strumento di grande utilità per collaborare con altre modalità d’intervento, risultando effettivamente insostituibile in determinate circostanze, ma in linea di principio difficilmente pensabile come unico e isolato in assenza di sinergie attuative. Un esempio fra i tanti illustrati in questi Atti, avendolo io seguito con assiduità particolare, concerne il bellissimo Crocifisso ligneo riferibile a Antonio da Sangallo (databile dunque ad un tempo indeterminato ma entro i primi due decenni del Cinquecento) restaurato da Francesca Spagnoli in quanto progetto vincitore della seconda edizione del premio dei Friends of Florence al Salone di restauro di Firenze. Mi riferisco in particolare alle alternanze nella liberazione da sostanze non volute sia delle epidermidi dipinte sotto la bronzatura ottocentesca, sia del panno originale con decorazioni dipinte che ne copriva i fianchi.
Il laser dunque è stato smitizzato, pur rimanendo un “intelligent tool”, come lo si definiva ai primi momenti nella ripresa delle sue applicazioni nel restauro, nei primi anni Novanta del secolo passato. Ecco allora l’importante contributo sulla “Determinazione della soglia di fluenza di danno nella pulitura delle superfici policrome”, utile per offrire indicazioni di riferimento a tutta una serie di ricerche, perché l’intervento sulle policromie adesso non è più un tabù, anche se continuo ad esser convinto che sia stato altamente opportuno arrivarci lentamente e per gradi.
Vedremo dunque i contributi sulla pulitura dei delicatissimi manufatti di arte contemporanea fra cui l’Achrome di Piero Manzoni, oppure dei fili metallici (e ricordo anche lo straordinario risultato ottenuto sul rarissimo Manto brasiliano di piume della Pinacoteca Ambrosiana di Milano, esposto alla mostra Restituzioni 2018 tenuta a Venaria Reale dopo il restauro realizzato da Guia Rossignoli).
Leggeremo di altri risultati, dopo quelli già pubblicati in diverse occasioni, raggiunti nella rimozione di concrezioni calcaree come anche di patine ossalatiche; ma soprattutto, almeno per me, anche perché ho voluto eseguire un controllo personale prima possibile data l’eccezionalità dell’evento, nella pulitura dei tre polittici veneziani di Hyeronimus Bosch, a dimostrazione dell’impiego del laser ormai anche nel caso di policromie di estrema delicatezza (e naturalmente, anche qui, in combinazione virtuosa con altri mezzi). è così che leggeremo con interesse i contributi che qui raccontano degli insegnamenti attivati nelle strutture di laurea magistrale accreditate, allo scopo di familiarizzare gli allievi con il laser fin dai primi tempi della loro formazione professionale.
Potremmo dunque parlare in conclusione, se soltanto si coglie il lato paradossale dell’affermazione, dell’essere divenuto oggi il laser non più strumento d’avanguardia e di eccezione, ma di vera normalità nella redazione dei progetti d’intervento e nelle applicazioni di restauro.
Ciò non significa che ormai conosciamo tutto, e che non ci sia ancora davanti a noi una prosecuzione della ricerca scientifica e delle sperimentazioni; ma soltanto che ci appare oggi quasi impensabile raffigurarsi un passato nel quale ancora per noi il laser nel restauro non esisteva proprio, oppure era soltanto un’ipotesi molto lontana, o al più una difficile sperimentazione.
E' così che fortunatamente da parecchi anni APLAR chiama a raccolta e riunisce la comunità nazionale (e non soltanto) degli operatori di restauro a mezzo laser; che ci informa, ci indirizza. Come è bello sapere che questo strumento esiste e è pronto a soccorrerci, così ci affidiamo alla nostra Associazione convinti, come si dice comunemente di qualcosa di molto utile, che “Se non ci fosse, bisognerebbe inventarla”. Nel nostro caso, fortunatamente ci ha pensato e ha provveduto Anna Brunetto.
Giorgio Bonsanti
Presidente della Commissione InterMinisteriale MIBAC-MIUR per l’Insegnamento del Restauro Chiudi

La sesta edizione del convegno APLAR si è svolta a Firenze presso l’Auditorium di Sant’Apollonia, in via S. Gallo, con il patrocinio della Regione Toscana. Il convegno, sulla scia delle precedenti edizioni (Vicenza 2007, Siena 2008, Bari 2010, Roma 2012 e Città del Vaticano 2014) ha confermato di essere un’importante occasione di incontro, sia a livello nazionale che internazionale, per la condivisione e la discussione di esperienze sulle applicazioni della tecnica laser nel restauro. Come ci è sempre piaciuto constatare, gli appuntamenti APLAR coinvolgono una nutrita platea di restauratori, segno evidente, da una parte, dell’interesse che la tecnologia laser suscita negli operatori della conservazione, mentre, da un altro punto di osservazione, si può confermare quanto sia viva e vivace l’attività concreta e “di cantiere” vista attraverso i casi oggetto di relazione.
In questa edizione il tema del convegno, così come esplicitato nel sottotitolo, era “i laser in combinazione con...”, un corollario sottile, volto proprio a stimolare la presentazione di interventi coinvolgenti la tecnologia laser non tanto come una “novità”, ma attraverso l’individuazione di una più matura progettualità integrata. In parole semplici APLAR 6 ha avuto l’ambizione di fare il punto sulle potenzialità di uso combinato della tecnologia laser con altre tecniche conservative, tradizionali o innovative, con il fine di raggiungere un risultato più vicino alle esigenze ed all’etica della conservazione. Possiamo dire con soddisfazione che l’intento del convegno è riuscito, in quanto sono state davvero numerose le relazioni che hanno illustrato l’integrazione dei laser in un processo più ampio di tecniche considerate “tradizionali”, finanche all’utilizzo delle apparecchiature da parte dai restauratori come un vero e proprio “arnese”, sia che fosse per “sgrossare” certe patine, sia per “rifinire” altri trattamenti, presentando in taluni casi interessanti protocolli.
Giova ricordare che nelle prime edizioni si assaporava l’uso del laser come la risoluzione definitiva delle problematiche conservative, sicuramente alimentata dall’entusiasmo per i casi risolti in cui appariva evidente come molti aspettassero una “rivoluzione” sulle metodologie di restauro, specialmente rivolta alla pulitura, magari proprio di quei casi particolarmente ostinati o dove fossero in gioco grandi superfici. Poi, in un naturale processo di maturazione, ci siamo imbattuti in casi particolari, in difficoltà organizzative (movimentazione in cantiere, sicurezza, costi degli investimenti o dei noli), che sono stati via via metabolizzati e integrati nei protocolli e nei capitolati. Infine l’inarrestabile propulsione dei centri di ricerca e di produzione dei laser che ha ampliato le possibilità applicative, la specificità dei macchinari, la loro produzione e diffusione.
È proprio questo uno degli aspetti più interessanti e innovativi che è scaturito dalla sesta edizione di APLAR. Confrontando il tenore delle decine di contributi che negli anni sono stati raccolti negli Atti del Convegno, si può osservare una progressiva presa di coscienza delle potenzialità espresse della strumentazione laser. Dopo un attento e cauto iniziale inserimento del laser in progetti eccezionali, sempre accompagnato da parallele sperimentazioni per valutarne efficacia e soglia di danno, il laser sembra finalmente entrato nella pratica di cantiere, affinando gli ambiti di intervento e aprendosi ad interazioni virtuose. Questi nuovi confini di impiego della strumentazione laser permetteranno di poterne prevedere l’uso, integrato con altre metodologie di intervento, sin dalla fase progettuale dell’intervento di restauro, ottenendo numerosi vantaggi sia nella razionalizzazione dei protocolli operativi, sia nella logistica di cantiere e nella organizzazione delle tempistiche e, non ultimo, anche nella gestione dei fondi economici. Da quanto premesso, risulta evidente quanto sia ancora più necessario questo appuntamento biennale che ci permette di coagulare esperienze e di fare il punto dello status del laser nel restauro.
In APLAR 6 gli interventi sono stati particolarmente articolati comprendendo applicazioni nel campo dell’architettura (2), dei dipinti murali (5) e dei dipinti mobili (5), dei manufatti cartacei (1) e tessili (3), degli stucchi (2) e dei gessi (1), della scultura lignea (2) e bronzi e oreficeria (3) per finire (e non sembri un’antitesi) nel campo dei reperti archeologici (4) e dell’arte contemporanea (4); sono state presentate anche un repertorio di esperienze di usi dei laser in Istituti dove vengono formati restauratori e tecnici (2); infine sono stati presentati anche 2 lavori con preziose informazioni riguardo al monitoraggio degli effetti dei laser. Si è confermata efficace ed attraente la scelta di presentare i Poster in 3 minuti con poche ma significative immagini: in tal modo si è lasciato lo stesso spazio a tutti i presentatori fomentando l’interesse della platea, che ha potuto poi approfondire personalmente con i relatori durante le pause.
I temi affrontati durante la Tavola Rotonda hanno dibattuto intorno all’attuale diffusione della pulitura laser nei Paesi Europei ed Extraeuropei, specificando le applicazioni sui diversi materiali, sul livello di conoscenza della pulitura laser negli Organismi Nazionali incaricati della Tutela del Patrimonio Culturale e sulla organizzazione del mercato nelle diverse realtà Nazionali; si è discusso inoltre della diffusione dei corsi di specializzazione ed, in generale, sull’organizzazione dell’apprendistato; infine, si è tentato di fare il punto sulla presenza di aziende nazionali di produzione di apparecchiature laser e di applicazioni di pulitura laser condizionate dai problemi locali nel reperimento di strumentazioni idonee. È stato molto apprezzato il servizio di traduzione simultanea, preciso e competente in materia, che è intervenuto biunivocamente, traducendo gli interventi esteri in lingua italiana e dall’italiano in inglese.
Importanti anche, data la locazione cittadina e l’ampia scelta, le visite organizzate dal Convegno, che hanno visto una numerosa partecipazione: sono stati visitati i Laboratori di Restauro dell’Opificio delle Pietre Dure, Settore Lapidei e Metalli nella sede di via degli Alfani e quelli di Restauro dei Settori Dipinti Mobili, Dipinti Murali, Scultura Lignea ed i Laboratori Scientifici alla Fortezza da Basso; una visita guidata è stata organizzata al nuovo Museo dell’Opera del Duomo, dove si trovano molte opere restaurate anche coi Laser; è stato guidato un tour nelle vie del centro di Firenze andando ad incontrare, in un percorso ideale a cielo aperto, numerose opere di varie tipologie, dai marmi, ai bronzi, agli stucchi, alle ceramiche, restaurate negli anni con il concorso della tecnologia laser; una visita è stata effettuata presso il centro di produzione di El.En. Spa a Calenzano.
Infine, non può non essere rivolto un ringraziamento per il patrocinio di numerosi Enti di tutela, Istituti di ricerca e conservazione, e al contributo di Imprese di restauro e di produzione di dispositivi laser, patrocinio che permette di sostenere e traghettare APLAR a nuovi, interessanti, futuri appuntamenti.
Anna Brunetto, Giancarlo Lanterna, Barbara Mazzei
Curatori Atti APLAR 6 Chiudi

Abstract
The essay presents the project and the results of the restoration works on the stone elements and decorated surfaces of the façade and the two courtyards of the Istituto degli Innocenti in Florence. The building, having at length been subjected to atmospheric agents and acts of vandalism and having been interested by some interventions in the past centuries, showed an accentuated degradation. Yet, from the planning of the intervention, the work group recommended the use of the laser: therefore, an accurate methodology has been determined in order to optimize the timing, the procedures and the results of the intervention. First, a cleaning with traditional tools (chemical and mechanical) has been undertaken on the most compact areas; then, the Laser technique has been used on the most decayed and delicate portions, with black crusts and heavy degradation, employing two different Q-switch wavelengths – A) 1064 nm and B) 532 nm – and diversifying the energy, the frequency and the spot diameter relating to the typology of surfaces and their alterations. Chiudi

Abstract
This work is the result of the experiences gained at the great restoration site of Porta Magna by Jacopo della Quercia (1438) and lateral portals by Amico Aspertini and Alfonso Lombardi (second decade of the sixteenth century) of the Basilica of San Petronio. The precious heritage of bas-reliefs and statues of the highest value required a careful preparatory study with meticulous bibliographic reconnaissance, in-depth archival research at the San Petronio Factory, together with an accurate system of diagnostic investigations. The analysis of the results of the tests carried out has allowed us to define the most effective guidelines for the entire recovery operation with the development of an operational protocol based on the constituent materials of the specific state of conservation. This operations were carried out by implementing various laser instruments: one Nd: YAG system in Short Free Running (SFR) regime with 1064 nm wavelength and pulse duration of 30-100 µs - a SFR with long pulse 200-1000 µs pulsers - and one Nd: YAG system in QS regime with 1064 and 532 nm wavelength. Chiudi

Abstract
This paper is about the study and removal of a thick layer of adhesive from a work, Laje # 19 (Herzog) AP1, made of reinforced concrete and newspaper, created by the artist Matheus Rocha Pitta. This adhesive (aqueous dispersion of polyvinylacetate) appeared as a bleaching covering the surface of the work and preventing its proper understanding. The different nature of concrete and paper used within the same work was the biggest challenge throughout the design of the intervention. Indeed, these materials have different conservative needs and are reactive to different substances. Therefore, different techniques (depending on the underlying substrate, paper or concrete) have been employed, in order to remove such layer. With regards to the cementitious base, the choice adopted was to use laser instrumentation which, together with other residual removal means, allowed the complete removal of the layer from the work. Chiudi

Abstract
The present paper regards about the laser cleaning intervention on three plaster casts, the Flora Farnese, the Pallade di Velletri and the Fauno Barberini, in the framework of the pilot restoration for the conservation of the Plaster Casts Collection of the Brera Academy of Fine Arts. The three artefacts were objects of a severe decay that altered the plaster casts integrity and impeded a correct lecture of the surface. Before using the laser tecnology, preliminary wet and agar gel cleaning were carried out. This metodology didn’t allow a complete deposits removal; in fact unwanted particles were partially penetrated in the gypsum matrix porosity and the traditional methods did not allow to eliminate the grey layer visible on the artefacts. Hence a Nd:YAG system operating in QS mode, was used as an alternative metodology. Several laser cleaning tests were carried out on plaster casts surface and instrumental analysis were carried out to evaluate the laser effects. Laser cleaning was completed at 532 nm wavelength. The possibility to calibrate continuously the operating parameters permitted to ensure selectivity, gradual cleaning and safety conditions needed to reach the desired cleaning level. The laser system allowed the treatment of a sensible, porous material like gypsum is, respecting at the best the surface morphology. Chiudi

Abstract
The cleaning of plasterworks could be often complicated by the presence of surface materials, originating from molding and patinas. Lasers allow dry cleaning with high selectivity, but guidelines for the cleaning of plasterworks finished with intentional patinations are unavailable. A set of tests was conducted to identify the range to perform a correct laser cleaning on plaster model samples patinated with beeswax, de-waxed shellac, Arabic gum and boiled linseed oil, using three laser systems: Nd:YAG devices at 1064 nm and 532 nm, both in Q-Switch, and a Er:YAG at 2940 nm, starting with the smallest values of fluence and repetition rate. The effects of laser cleaning on model samples were evaluated with colorimetric, gloss, contact angle measures and stereo-microscopic observations; considering the results obtained, damage was identified on the patina and/or on the plaster substrate with the Er:YAG system, starting at a minimum of 0.50 J/cm2 and a repetition rate of 1 Hz, with the exception of the shellac treatment, which showed neither morphological or optical variations, up to the fluence of 1.25 J/ cm2 with repetition rate to 5 Hz. The shellac had variations in color with the Nd:YAG at 1064 nm @ 0.79 J/cm2 and a 2 Hz; no chromatic variations resulted for the remaining three patinas in the range of fluences tested, with values between 0.31 J/cm2 and 1.1 J/cm2, with repetition rate up to 3 Hz. No effects were detected when cleaning with the Nd:YAG at 532 nm, which was effective to 2.4 J/cm2 with increasing repetition rate, up to a maximum of 2 Hz. Chiudi

Abstract
The contribution presents the experimentation and the intervention of rediscovering drawings, signatures and dates, made over time, with sanguine pastel and graphite, mainly found on the lower parts of the pilasters and the stucco-works inside the Carracci Gallery in Palazzo Farnese, in Rome. The first photo-ablative treatment trials, under different conditions and parameters, confirmed the possibility of recovery and the consistency of the areas on which to intervene with Laser equipment. In addition to the Nd:YAG @ 1064 nm laser in LQS and SFR modes, QS lasers were tested in the harmonic of 532 nm and 355 nm on stucco specimens with graphite inscriptions set up in the laboratory. The Er:YAG laser (λ 2940 nm) was also included in the intervention phase. Video-microscope photographs and colorimetric tests, both before and after the interventions, in order to certify the level of attainable ablation and to check for any colorimetric modifications attributable to the techniques used, supported the cleaning tests. The interventions where preceded by high-resolution digital camera shots of all the areas to be submitted to the ablative treatment procedures. Chiudi

Abstract
by a conservation graduation thesis, at Brera Academy of Fine Arts in Milan. This thesis had the purpose of verifying the possibility of performing a “descialbo” with different sources laser on plaster artifacts. Plaster model samples were designed and prepared with the traditional molding technique. On their surfaces, was applied a thin layer of shellac and, then, three different types of scialbo were applied. The laser ablation tests were performed with two different sources - neodymium and holmium - using different operating procedures (dry and wet) in order to identify the appropriate fluence parameters for removing the scialbo layer. The effects of irradiation and the different levels of cleaning were evaluated with the aid of colorimetric analysis and with the observation of cross-sections by Optical Microscopy. Chiudi

Abstract
This work has the object of removing oxalate deposits from a plaster-embossed surface, painted with gouache tempera technique. After removing the deteriorate film layers, the intervention saw the use of laser instrumentation, which was found to be essential for working under the aged natural varnish on the surface, particularly susceptible to chemical action, mainly due to the numerous orographic details and the conditions of great fragility of the pictorial film, previously consolidated. Initial tests were carried out with different types of lasers Smart Clean II Short Free Running (λ1064 nm), EOS 1000 Long Q-Switch (λ1064 nm), Thunder Art (λ1064, 355, 532 nm). The most effective laser was the EOS 1000 in LQS mode. The ablative result of the treatment was verified by a portable electronic microscope in visible light. Removing the overlaid materials has allowed the recovery of the original molds, allowing the correct reading of the plastic and permitting geological use and study. Chiudi

Abstract
The frescoes in the apse of the Tarquinia Cathedral were painted by Antonio da Viterbo (1450-1516). It is the most important work of this painter, commissioned by Bartolomeo Vitelleschi and realized in 1508. In 1643 these frescoes were damaged by a fire, as a result of which the surfaces were covered by a black layer, that became insoluble over time. This insoluble layer was investigated with portable Mid-FTIR, µFTIR in transmission mode and µFTIR-ATR mapping. The analytical results have detected the presence of calcium oxalate. The removal of the oxalate film with a chemical cleaning from a carbonatic substratum was very risky, this is why the choice focused on laser technology. The selectivity of laser Nd:YAG, λ 1064 nm, Long Q-Switching (100 ns) allowed to recover the colours and permitted to give back the correct reading of the surfaces. The effectiveness of the laser ablation was performed by optical measurements, examinations on surfaces with digital microscope and of cross-sections. Chiudi

Abstract
The mural painting “Lasciate che i bambini vengano a me” by Tomaso Pasquotti painted in 1889 and located inside the canteen of the Rossi kindergarten in Schio (Vicenza, Italy), was severely damaged by fire in 2009. A campaign of measurements in situ was organized for the definition of optimal operating protocols in view of a project of restoration and recovery of the painting. For this purpose, advanced portable instrumentation based on optical reflection spectroscopy, colorimetry and Raman spectroscopy were used in order to identify the color palette for understanding the execution procedure and to characterize the state of conservation of the pictorial layers. A few samples were taken and analyzed through X-Ray fluorescence spectroscopy; moreover, cross sections were prepared to be observed by means of optical and electronic microscopy (ESEM-EDX). In addition, a series of laser ablation tests were performed to explore the potential of this technique for the removal of thermally altered layers and deposits. In particular, four laser systems were tested allowing remarkable operational versatility: Nd:YAG, QS, LQS and SFR and Er:YAG. The tests showed how the appropriate calibration and combination of Nd:YAG LQS and SFR systems allow significant readability of most of the different pictorial areas, while the Er:YAG FR system proved to be particularly useful in presence of cinnabar. The results obtained so far highlighted a very complex conservation situation. However, by using Nd:YAG SFR and LQS systems, practicable recovery margins were achieved. Chiudi

Abstract
was devised on the basis of the surface temperature control by infrared (IR) thermal camera (Avio, InfReC R300SR). Er:YAG and Nd:YAG laser sources, in different operative modes, were tested on several wall paintings mock-ups removing a layer of an aged alterated fixative. The mock-ups were realized as painting buon fresco in yellow ochre on a lime and sand based mortar. After the carbonatation process, some samples were treated with a mixture of PVA at 5% and nero vite, while others samples were treated with a mixture of shellac (at 5%) and nero vite. The heating of the surface during the cleaning was monitored by IR thermal camera with a high frame rate, up to 60 fps (frame per second). The peak of temperature during the laser treatment and the thermal diffusion of the laser action were analysed also in relation with the use of water normally used by restorers during the cleaning. The tests were performed so as to detect the damage temperature threshold for the wall painting mock-ups. The IR thermogarphic inspection was complemented by optical microscope observations and reflectance FT-IR spectroscopy investigation of eventual compositional alteration. Preliminary results show the effectiveness of the proposed approach in establishing the safe laser operational conditions to avoid any undesirable thermal stress induced during laser cleaning. Chiudi

Abstract
The study in exam is born by the inexistance of an exaustive bibliografy that could report the behaviour of pictorial layers under the action of different tipology of laser (the laser cleaning of the painted coats is heavily influenced by the operating parameters). At equal wavelenghs used of the laser radiations, during the treatment some painting films do not suffer physical, chimical or physico-chemical changes, remaining intact, instead other, in the same contitions suffer from irriversible changes. Different laser strumentations and instructions to use are instead responsable of different effects, negative either, for the painting films conservation because the influence on the optical proprierties and the radiation dept penetration, or phisical processes which can cause thermal damage in case of long pulses or photomecanical damage in case of short pulses. They can then be verified damages because of photochimical, phototermal and photolysis effects (ablation, destruction). To define also, the different behaviour of sample with different pictorial layers, it has been defined an experimental protocol which provides for the action of different laser typologies varied among them for wavelenghs, pulse duration, frequency and fluence. At first it was decided to identify the thresholds of the painting damage (values below which is it possible to operate in a security condition) applied on the different supports with different executive techniques: painting on canvas with a plaster and glue preparation, fresco paintings samples and, in the end, sample paintings with dry spreaded. Every sample was subjected to the laser action, keeping the spot size and the distance from the surface unchanged, increasing fluency up to the possible appearence of demage phenomenology (phisical, chemical or mechanical), documented with 3D microscope tecniques. In a second step of experimentation, were tacken samples with the same executive techniques used for the determinazion of the demage influence thresholds but with overlapping layers of organic nature (animal glues artificially aged). This samples were subjected to cleaning tests by re-determining threshold of damage. Data processing of pigment/ binder/ overlapping layers has made it possible to find the best operating conditions ideal for polychrome surfaces cleaning and being able to have numerical references of the fluence in the choise of laser types and operating conditions. Chiudi

Abstract
During a restoration project in the church of S.Costanzo in Ronciglione (VT), traces of figurative paintings have been found on the dome’s walls. Given the compromised state of walls, the paintings restoration was only possible after the full structural intervention. The painting film, although very deteriorated, still showed several decorative pieces, irregularly overlapped in 2/3 painted layers. Plaster substrate was extremely disaggregated and with efflorescences. The most ancient layer showed a fresco with a glory of angels, of very fine manufacture.The dramatic degradation of polychrome layers prevented using mechanical tools, like lancets or compresses, and laser cleaning revealed as the most effective technique. We took advantage of a Combo Eos system, whose flexibility in operating parameters was very important, given the variability of impact points physical characteristics that required frequent changes of the pulse energy levels to achieve best results. Chiudi

Abstract
In the XVIII Dynasty (1552-1324 B.C.) the Egyptians conquered northern Sudan (Kush/“Upper Nubia”) and named Gebel Barkal the birthplace and main southern residence of their state god Amun. The Egyptian expansion resulted in the establishment of the Amun cult in many places throughout Nubia, but none was as important as Gebel Barkal. The status of this region saw an enormous increase during the XXV Kushite dynasty (747 – 656 B.C.) with the building of many monuments and temples. In the last past years, the Italian Institute for Conservation and Restoration (ISCR) has been heading a conservation and restoration campaign at Mut temple. The campaign includes the cleaning of a series of important wall paintings located in the main hall of Mut temple, a partially hypogeic construction. In December 2015, a mission lead by Maria Concetta Laurenti was undertaken with the aim of evaluating the efficacy and selectivity of laser treatments in the removal of accretions and deteriorated materials from the Mut temple wall paintings. This evaluation also took into account aspects regarding the integration of traditional cleaning methods with laser technology, setting up working conditions and assessing the main characteristics of the removed material as well as establishing the correct criteria for the desired cleaning level. The general conditions of the wall paintings were complex and legibility was highly hampered by a diversity of deterioration processes. The painted surfaces were concealed by a thick layer of atmospheric particulate, black patinas and concretions produced by bat dung and other photophobic animals. Cleaning tests were undertaken using El.En. Eos QS and Eos 1000 LQS lasers, in order to verify the viability of different IR wavelength pulse durations: Short Free Running (SFR), Long Q-switched (LQS) and Q switched (QS) modes. Pigment identification resulted in: Egyptian blue, red/yellow ochre and atacamite. Quantitative changes of colour in the pigments due to laser irradiation were measured with MINOLTA CR700d Spectrophotometer using CIE L*a*b* systems for data evaluation. All tests showed a net increase in surface brightness due to the removal of superficial accretions and an increase of a * and b * values according to the different tested colours. Best results were achieved in dry conditions. Results, including tests undertaken to verify pigment preservation post treatment, concluded that laser technology is a viable alternative/tool for the cleaning procedures of wall paintings with technical characteristics similar to those at Mud Temple. Chiudi

Abstract
The church of San Giovanni is one of the main monuments of the city of Saluzzo (CN); nevertheless, the state of conservation of the building is very precarious. Between July and November 2015, it was possible to intervene on a mural painting on the fourth bay of the left aisle, in order to remove the layers of later paint. The closest one to the painting was white, thick and very coherent and, consequently, its removal with usual methods was very dangerous. The focus of the first intervention was on the mechanical thinning of the layer while, during the second one, the removal was completed with the use of Nd:YAG laser systems. In particular, three devices were used: Thunder Art QS laser, Eos 1000 LQS laser and Smart Clean II SFR laser, with different pulses and excellent results. Chiudi

Abstract
This paper presents the combined use of laser and chemical techniques during a localized removal treatment of non original materials on the three polyptychs by Hieronymus Bosch. The paintings: “Santa Liberata Triptych”, “Hermits Saints Triptych”, and the four panels with the “Visions of the Afterlife”, executed in oil on wooden panel, belonging to the Gallerie dell’Accademia Museum in Venice – The painted surface was affected by a grey non-original layer of protein-based substance that was mostly transformed into calcium oxalate. Nd:YAG lasers have been tested and used at 1064 nm in pulse mode LQS (120 ns) and SFR (60-120 µs) and laser Er:YAG at 2940 nm in the Very Short pulse mode (150-200 µs) and Short (300 µs). After laser treatment, the finishing of the cleaning was carried out by applying a solvent mixture, composed of white spirits and isopropanol or deionized water and isopropanol with different percentages and thickened with carbopol. A large campaign of preliminary and work in progress investigations were analyzed in depth and monitored during treatment through macro and micro photographs, UV fluorescence, cross-section, XRF, FT-IR and Raman spectroscopy. Chiudi

Abstract
A combined approach of laboratory and in-situ techniques was successfully exploited for assessing the cleaning effects on a XIV century panel painting. The cleaning procedure was implemented by using traditional chemical methods following by the application of Er:YAG laser. Both cleaning treatments were aimed to remove a thick superficial layer primarily consisting of calcium oxalates as confirmed by micro-destructive analysis. Specifically, after the laser application a stronger decrease of calcium oxalates in combination with the detection of the original painting materials, was non-invasively proved through the use of reflection FTIR spectroscopy. In addition, imaging techniques, 3D video microscopy and colorimetry allowed the monitoring of morphology and color changes of the painted surface. Chiudi

Abstract
This work aims at the development of a cleaning methodology for twentieth-century varnished oil paintings using Er:YAG lasers emitting 2.94 µm pulses. The study evaluates the Er: YAG laser efficacy to safely reduce thin varnish layers on such paintings. Tests under single and multiple laser pulses, fluences ranging from 0.56 J/cm2 to 2.40 J/cm2, on dried and wetted surfaces of the painting were carried out by applying polar and apolar solvents. Glass coverslips were placed on the painting during irradiation to collect the ablated fragments. Principal component analysis maps of multispectral images of the treated surface indicated the efficiency of the procedure. Further evaluation was performed by optical microscopy and colorimetry. Chiudi

Abstract
This study compares different typologies of cleaning techniques for the conservation treatments performed on egyptians archeological object and reports the procedures and the results of the experimentation performed on specimens made specifically by egyptian blue pigment. The object comes from the Egyptian Museum of Turin and is composed of a small wooden coffin and an anthropomorphic mummy covered with cartonnage. The litterature data about the conservation treatment of egyptian blu are scarce and do not include a specific and selective treatment for this colour. The specimens were made to imitate the surface, the composition, the colour and the state of conservation of the original surface in order to calibrate and test the best methodology. The cleaning of egyptian blue on the specimens was challenging due to the high porosity of the surface, high sensibility to water and strong cohesivness of dregs. Chiudi

Abstract
During the Conservazione e Restauro dei Beni Culturali Master’s dregee thesis project, the laser cleaning of the shabty-box (CAT.2441) decorated surfaces has been applied. The artifact was coming from the Turin Museo Egizio collection. The artifact showed a widespread consistent sediment layer, especially on the topside and close to the cover that was affected by an earthy sediment. It was thought to apply the dry cleaning method to wipe the artefact, but it has not been shown to be effective due to the consistent deposit layer; to replace it the laser oblation has been chosen. This methodology allowed to promptly monitor the treated areas. The applied range has been chosen after ad hoc test on several box areas, followed by microscopic observation of the cleaning pieces. The various scenarios identified lead to a selective cleaning, that mainly interested the back preparation: as a result a mid-level cleaning has been achieved, preserving the thinnest layer due by the artifact aging. Chiudi

Abstract
The aim of this contribution is to illustrate the evolution of the laser ablation cleaning method adopted in three different conservation interventions on the Baptistery Gates: from its first use on the reliefs of the Porta del Paradiso, to its emplyment on the North Gate, finally to its role in the treatment currently undergoing on the South Gate. Over the many years dedicated to these interventions various parameters have changed: the working group, the equipment, the solutions designed to protect the working areas and the refinishing cleanings method. These are the points addressed to illustrate the progress of our conservation experience with the laser ablation cleaning method. Chiudi

Abstract
The present work is extracted from the master’s thesis of Yijia Shen on the study and conservation of Sino-Japanese bronze mirrors from the Pigorini Museum collections in Rome1. The decorated sides of the Edo period mirrors in discussion were covered by layers of dust and metal soaps, a mix of corrosion products which could provoke further degradation. Mechanical or chemical methods were proved to be unsuitable due to the scratchable consistency of the alloys and the submillimetric dimension of the bas-relief undercuts. As an alternative, optical pulses generated by a 1064 nm Nd:YAG laser equipment at Long Q-switched mode were tested. The results were verified with SEM-EDS and digital video microscope. Efficient and safe cleaning was obtained with the fluences of 1~1.8 J/cm2 operated at a low frequency of 2 Hz in order to move freely on the uneven surface wetted by deionised water. To remove eventual remains, conventional methods are recommended rather than repeating too many pulses. Chiudi

Abstract
The gilt bronze head depicting the Emperor Antoninus Pius, from the excavations of Veleia and on display in the National Archaeological Museum of Parma, is a Roman period artwork (138-161 d.C) of extreme quality, both from a technical and artistic point of view, representing an important contribution in the field of studies on ancient bronzes. The artwork has recently been subjected to a cleaning intervention and reassembly of its fragments. The conservation issues of the head are related to the mechanical instability of its various parts and fragments, worsened by previous interventions with the reassembly of its fragments, probably after accidental falling. The problems are also related to an advanced corrosion of the bronze causing in turn the high fragility of the gold leaf layer, as well as to the massive presence of many inner filling materials. The gold leaf gilding has many losses, microblisters and a scarce adhesion to the highly mineralized bronze underlayer and is largely covered by calcareous-earthy concretions and organic layers applied in the past. Due to these highly critical issues, laser cleaning considered as an alternative to more conventional methods, combined with mechanical ablation, allowing to regain a good perception of the artwork’s surfaces and of the Emperor’s natural facial expression. Chiudi

Abstract
This paper focuses on the laser cleaning of metallic threads present as decoration on an ancient liturgical vestment (chasuble) using a Nd:YAG laser radiation in the visible region of the spectrum (532 nm). This cleaning method, had been used in the past for some famous historical fabrics such as the funeral garment of Sigismondo Pandolfo Malatesta (1997-2000), the velvet and silver satin of the same suit, and the altar frontal of Beata Giulia (Church of Saints Jacopo and Philip of Certaldo) made of silk, silver and golden silver. In short times it ensured the removal of the thick layer of oxidation and organic deposits present on the metal surface, providing the safety conditions for the artifact. The laser cleaning treatment revealed the ancient splendour of the chasuble and it was once again visible the richness and variety of decorative form, materials and techniques used for its production. Chiudi

Abstract
Cleaning of metallic threads has been a recurrent dilemma in historical textile conservation. Careful selection of restoration methods is in fact required because decayed metallic threads are wrapped around natural textile fibers. This article synthesizes the results of a conservation study undertaken at the Accademia di Francia in Rome of a silk velvet cope. The artefact, a silk velvet cope with different types of metallic threads, dating from the 15th century, coming from the collection of the Musée des Tissus de Lyon in France, was the subject of experimental cleaning tests using laser ablation and other technologies to ascertain the most effective method of cleaning compound textiles. Two laser instruments with variable wavelengths and pulse length were tested: laser Nd:YAG, QS at 1064 and 532 nm, and the laser Nd:YAG, LQS at 1064 nm. The laser tests were focused on the cope’s metallic fringes, presenting three types of wires of different shape, composition and state of degradation. Parameters such as frequency, pulse, and beam size were adjusted to match the small size of the metal strips and to avoid any damage to the silk fibers over which they are wrapped. The effectiveness of the cleaning levels of the metallic threads have been evaluated through SEM-EDS, as well as the evidence of any damage to the organic fibers. Chiudi

Abstract
The discovery of more than 1600 glass sectilia during the archaeological excavations on the Roman villa in Aiano (IV - V century BC) has required the definition of punctual strategies to gather, catalogue and restore the fragments. After dusting the surfaces, the conservation and the morphology of fragments have been examined; chemical and physical analysis also helped to detect matters and procedures. Careful tests have been then made in order to identify the best methods to remove any residues due to burial; laser ablation has been identified as the most efficient and respectful of the brittle glass surface. The cleaning has been made via a double emission - Q-Switch (pulse duration 15 ns, energy from 10 mJ to 140 mJ) and Short Free Running (pulse duration from 30 to 100 µs, energy from 100 mJ to 1 J) laser – continuously verifying the results through Dino Lite Digital and Digital 3D Microscopy. Scanning Electron Microscopy (SEM) has been also used to investigate glass composition and structure, as well as to check the effects of the laser ablation on the original surfaces. Chiudi

Abstract
This paper presents the results of the laser cleaning tests on archaeological artifacts(finds) in ceramics and glass, found in the Necropolis of the Via Triumphalis in the Vatican. Diagnostic investigations, such as micro-FTIR infrared spectroscopy and pyrolysis, SEM and UVF investigations, have revealed the nature of overlaying substances such as earthy encrustations, traces of manganese and very tenacious carbonate and silicate concretions. The first cleaning phase was performed through traditional methodology (chemical-mechanical). The unsatisfactory results, led us to evaluate the applicability of laser technology. For the glass finds, the appropriate laser system and the most suitable operating parameters were identified, comparing the following systems Nd:YAG λ 1064 nm in SFR, LQS and QS mode, commercially known as Smart Clean II, EOS Combo of El.En., Art Light II Lambda Scientifica, Thunder Art of the Quanta System, and Phoenix compact of the Lynton. For a greater control during the ablation, semirigid gels with different pH levels and/or some filters were interposed between the laser beam and the artifact. As concerns the ceramic finds, the carbonate/silicate concretions were not effectively removed by the laser. The absorption coefficient of the laser radiation was therefore incremented by coloring the concretion with a mixture of pigmentbinder with an excellent covering power of 4/5 (natural shadow ground, refractive index: 2.10). This improved the interaction of the laser with the concretions, ensuring a gradual and homogeneous result. Chiudi

Abstract
The sculpture of Urania of 1807, present in the Napoleonic Museum exhibition of Rome (INV. MN348), in biscuit of Sèvres, with a surface without “vetrina” and therefore scratched and wrinkled, shows on the surface a considerable amount of dust that, as with the residues of previous treatments, made the art object look unpleasant. The photo shoot in Fluorescence UV highlighted the area mostly damaged. The atoxic cleaning with agar-agar gel, also chosen to facilitate the removal of substances, has given excellent results except for some dark spots and yellowish surfaces on which it was necessary to intervene with laser cleaning. After conducting cleaning tests using Nd:YAG laser with an emission at 1064 nm: a Short-Free-Running laser (pulse duration between 60 µs and 120 µs) and with Long Q-Switched lasers, we chose to use the Nd:YAG LQS laser. The optimal result was achieved availing of a combined cleaning procedure with agar-agar gel and laser applications. Chiudi

Abstract
Laser cleaning of various paper samples artificially contaminated with ink, soot and rust is demonstrated. The purpose of this work is to compare the cleaning efficiency of three laser systems:
-Copper bromide vapor laser (CuBrVL) generating nanosecond pulses at 510.6 nm and max. pulse repetition rate 20 kHz;
-Q-Switched Nd:YAG laser generating nanosecond pulses at 1064 nm and 532 nm and pulse repetition rate 1 Hz and 10 Hz;
-Ti:Sapphire laser generating femtosecond pulses at pulse repetition rate 1 kHz with wavelength tunability option from 240 – 2600 nm.
Optimal cleaning parameters, such as laser fluence, wavelength, pulse duration, pulse repetition frequency, are determined for each specific case in order to remove gently the contaminations avoiding any harm to the paper surface. The results are evaluated with digital microscopy. A pre-assessment of the optical properties of the paper and the stains in terms of full diffuse reflection in the spectral range 200 – 2000 nm is also done. Chiudi

Abstract
Before restoring ancient and valuable ethnographic objects many aspects should be taken into account, because lignocellulosic fibers-based materials undergo different and concomitant degrading reactions (oxidation, hydrolysis, depolimerization) over time. Basically, dry cleaning methods should be preferred, as they are potentially less invasive in the long term, especially for the easily hydrolysable components. Here, the fundamental and second harmonic of Q-Switch Nd:YAG laser, were comparatively investigated for dealing with the removal of soiling (soot, dirt, aluminum silicates, carbonaceous material) from a woven-fibers angarêb bed, which is preserved at Africa Hall of the National Geographic Society Museum (Cairo, Egypt). Besides fiber identification, laser induced-effects were assessed on angarêb fibers by means of stratigraphic examination, Vis-NIR fluorescence emission, Raman spectroscopy, ESEM-EDX analysis and optical microscopy observations. Irradiation at 532 nm negatively affects color appearance and structural integrity of fibers. Bond-breaking/depolymerization followed by bleaching, due to the significant absorption of lignin/phenolic-carbohydrate and lignin-quinonoid complexes, occur at this wavelength. The promising results achieved at 1064 nm, in term of chemical and structural integrity, highlight the possibility of using this wavelenghth for treating soiled and untreatable ethnographic material. Chiudi

Abstract
The sewn cloth Achrome by Piero Manzoni had large stains and a layer of dirt of a gray tonality. Mounted on a stretcher, on a lining canvas with a strongly yellowed preparation. After a microaspiration of the dust, a dirt removal treatment with a laser device Nd:YAG; l 532 nm, QS (8 ns), was performed. However, the work still maintained yellowing areas, particularly marked where the sewn fabric was most in contact with the preparation of the lining canvas. At this point, a yellowing reduction test was performed with a 30 W LED lamp for a duration of 50 hours at about 18.000 lux. After the test, a slight but encouraging reduction in the yellowing was perceivable. The operation, repeated several times with different exposures times and procedures, continued on the remaining areas. The result was a clear and uniform tonality across the entire surface, probably closer to the original conceptual thought of the artist Surveying on cloth and lining support was carried out by optical microscope analysis, FT-IR microspectroscopy and macro-photographic reproduction. Chiudi

Abstract
This paper describes the development of techniques using a combination of lasers, solvents, and chelators to remove overpaint in the treatment of a 15th century polychrome wooden Crucifix attributed to Antonio da Sangallo, made for the Painters’ Chapel, inside the “Santissima Annunziata” Basilica in Florence. The original polychromy of the Crucifix was later entirely concealed by a brown overpaint in order to simulate the appearance of bronze. The materials (pigments, binders, overpaints and coatings) were analysed before and during all steps of the restoration, through stratigraphic analysis of cross-sections, FT-IR microspectroscopy and surface examination using digital microscopy. The decision to recover the original polychromy led to testing with various chemical and mechanical cleaning methods: chelating agents thickened in polysaccharide polymers, varying application techniques, the pH and concentration of gels and chelators. During the course of treatment, laser techniques were tested in order to understand their effectiveness for the removal of overpaint from the skin of Christ and the painted fabric loincloth, the latter being particularly sensitive to chemical treatments. Nd:YAG lasers were used at 1064 nm in the SFR and LQS pulse modes, respectively 60-120 µs and 120 ns; the laser in LQS was tested in all three pulse modes. Er:YAG lasers (λ 2940 nm) were also used in the Long Short (700 µs), Short (350 µs) and Very Short (250-100 µs) pulse modes. The results obtained were promising, so it was decided to use lasers for the treatment of the loincloth. After further testing showed the combined action of lasers and solvents to be effective, treatment was undertaken on the wood of the cross with solvents and lasers, and the skin tones were cleaned using lasers followed by chelating agents. Chiudi

Abstract
The cleaning and restoration of the fifteen tiles of the “Misteri del Rosario” cycle from the S. Stefano parish church in Chiusanico (IM), oil paintings on iron/tin plates, presented itself as a particularly hard task. Time corrosion and, more recently, water infiltration from the roof had actually caused extensive damage with rust formation, raising of the color layers and loss of painting from significant portions of the surface, thus almost completely compromising (together with dirt and dust) the readability of the artefacts. Restoration has been performed by means of repeated pioneering laser-cleaning treatments (Nd:YAG and Er:YAG instruments) alternate with solvent-gel chemical cleaning, with final fixation of the residual polychromy with a low-concentration solution of an acrylic resin. A preliminary diagnostic campaign served to identify materials while image processing before and after restoration confirmed a sensible intensity increase of the chromatic components, although with preservation of the original colors. Chiudi

Abstract
This paper describes the results of the technical-scientific and operational study activities carried out on a work of cabinetmaking, an elaborate structure, decorated by use of different materials: veneers made of various woody species, metal inserts, ivory, tortoiseshell and mother-of-pearl elements. The polymateric nature of the works required the implementation of differentiated intervention modes for the removal of consistent surface deposits, which in some cases envisaged the integration of chemical systems with physical methods. In particular, the action taken with laser technology proved to be crucial, first testing the effectiveness of the Eos 1000 LQS @ 1064 nm and Thunder Art @ 355 nm laser. The fine ivory sculptures, applied to the structure with pins of analogous matter, showed a thick coherent dirt layer, removed in a first phase by physical methods and in a second phase by cleaning carried out with an aqueous solution; Golden brass decorations were blurred by a thick layer of black oxidation, which gave to some adjacent areas of ivory a greenish shade. In this case the laser was essential for a first level of removal of the Oxidation, followed by a dry cleaning system. The combination of macro photographs of the details of the artifacts, with non-invasive analytical techniques -ultraviolet fluorescence, optical and electronic microscope, thermocamera- allowed to monitor and document the cleaning procedure during all the operational phases in order to ensure a suitable and homogeneous action and to safeguard the surfaces of the masterpiece. Chiudi

Abstract
The essay gathers some experiences in the use of Laser technology carried out during the three-year restoration courses in the Institute for Art and Restoration Palazzo Spinelli. Thanks to the agreements signed with the Municipality of Florence and with the Monumental Cemetery of the “Porte Sante” at the Basilica of San Miniato al Monte, it was possible to restore some relevant monuments such as the Monumento Piatti in San Miniato, the Lion sculpture from Viale del Poggio Imperiale and other works. Preliminary cleaning tests have been carried out, in which some particularly tenacious concretions - after being softened by chemical and mechanical methods - have been removed thanks to the laser application. Two laser tools have been used, in order to achieve extremely satisfactory results: the laser Nd:YAG Short Free Running (SFR) 1064 nm wavelength and fiber-optic beam transport and the laser LQS Long Q-Switch: A) 1064 nm B) 532 nm, diversifying frequency on the different surfaces. All phases have constantly been inspected and verified through the Dino Lite Digital Microscope. Chiudi

Abstract
The essay presents the experiences in the application of laser technology during Restoration classes (PFP1 professional profile) at the Accademia di Belle Arti de L’Aquila. The study focuses on theoretical and practical knowledge both on materials and degradations of artworks and on traditionals cleaning methods and the use of laser technology for cultural heritage. Tests have been made through two laser instruments: the first one with double emission mode 1a) Q-Switch and 1b) Short Free Running, and the second with Q-Switch impulse and two wavelength: 2a) 1064 nm and 2b) 532 nm. Chiudi

Abstract
The Italian project Cobra had among its objectives to address real case studies in the Latium region to demonstrate the effectiveness of possible interventions of innovative technologies. In particular, in this work, the results of laser cleaning actions obtained with an EOS Combo laser system provided by El.En. are presented. A first activity concerned the laser cleaning carried out in the frame of the restitutive restoration of the original renaissance fresco decorating the dome of the church of San Costanzo in Ronciglione. Here two or three layers of paint, laying on an extremely crumbled substrate, were on the surface, in addition to large, deep and complex degradation forms with the presence of efflorescences. The EOS Combo was, then, used for the removal of encrustations on finds from the Domus Valeriorum al Celio. In laboratory such system was tested for the cleaning of forms of biodegradation on historic marbles and for the removal of protective nanocomposites on stone. Chiudi

Abstract
We present results on the application of Laser Cleaning (LC) on copper archaeological plates; decorative pieces of antique furniture and plaster sculptures that belong to Argentine museum collections. By using pulsed Nd:YAG lasers at 1064 nm we remove active corrosion, surface dirt and marks for classification on these pieces. We compare the results with traditional cleaning methods and we show the advantages in the case of fragile pieces or objects with carved surface. We also show cases in which the combination of LC with standard techniques is the best option for the restoration of the pieces. Chiudi