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U V L A S

 

ECHIPAMENT LASER PORTABIL PENTRU DECONTAMINAREA OBIECTELOR DE ARTA ŞI DOCUMENTELOR

 

 

Roxana Radvan*

Roxana Savastru*

Cristian Deciu*

Walter Maracineanu*

Ioana Gomoiu**

Dan Mohanu***

 

 

 

 

 

 

 

 

 

INTRODUCERE

Lucrarea prezintă succint principalele etape parcurse în vederea realizării unui echipament laser portabil pentru decontaminarea materialelor specifice. Studiul efectului letal sau de reducere a viabilităţii unor specii microbiologice selectate dintre cele mai răspândite şi a aprecierii eficienţei iradierii laser a repre­zentat prima etapă de studiu. Verificarea stabilităţii cromatice a stratului obiec­tului de artă – cel mai adesea  policrom – în urma iradierii laser în aceleaşi condiţii a reprezentat a doua etapă de lucru care a precedat realizarea modelului UVLAS. 

Trebuie subliniat că evaluarea viabilităţii este efectuată pentru probe cu un net avantaj către dezvoltare decât cele aflate în condiţii reale. Prin urmare, rezul­tate modeste în reducerea viabilităţii culturilor monitorizate conduc la rezultate pozitive în condiţii concrete.

 

DETERMINAREA REGIMULUI OPTIM DE LUCRU PENTRU UVLAS

 

Microorganisme implicate în biodeteriorarea picturii murale

Microorganismele care se dezvolta la suprafaţa sau în profunzimea picturii murale aparţin bacteriilor, fungilor şi algelor. Tipul de microorganism predominant este dependent de compoziţia chimica a substratului, temperatură şi umiditate. În timp, acelaşi substrat va fi colonizat de diferite tipuri de microorga­nisme care determină apariţia unor morfologii specifice de biodeteriorare. În timp, bacteriile chimioautotrofe şi cele autotrofe încetează activitatea vitală şi îmbogăţesc în compuşi organici substratul. Aceste modificări de natură chimică determină dezvoltarea bacteriilor heterotrofe (nu au capacitatea de a sintetiza compuşii organici; în nutritie îi preiau din substrat).

Prezenţa compuşilor organici de origine biologica într-un substrat anorganic favorizează şi dezvoltarea fungilor microscopici (microorganisme heterotrofe). Frecvent întâlnite pe pictura murală sunt genurile: Aureobasidium, Ulocladium, Cladosporium, Walhemia, Penicillium, Aspergillus, Geotrichum, Mucor, Rhizopus.

Acizii anorganici (H2SO4, HNO3) sau organici (citric, oxalic, gluconic) acţionează ca agenţi de chelatare, extrăgând ionii de calciu, magneziu, fier, astfel încât suprafaţa respectiva îşi pierde integritatea prin modificările de coeziune. Enzimele (amilaze, proteaze, celulaze) acţionează asupra substraturilor specifice (amidon, proteine din cleiuri, celuloză). Acestea determină de asemenea pierderea coeziunii substratului. Pigmenţii sunt localizaţi în celule sau sunt eliberaţi la exterior determinând modificări ale culorilor (modificări estetice).

Microorganismele pot acţiona ca biodeteriogeni şi mecanic. Astfel hifele fungice sau ale actinomicetelor pătrund prin fisuri determinând lărgirea acestora. Acest mecanism de acţiune nu este izolat şi este însoţit de cel biochimic. În procesul de aderare a unor microorganisme, la substrat intervin polizaharidele extracelulare care acţionează direct asupra substratului pictural.

Distribuţia numerică a microorganismelor pe pictura murală existentă într-o biserica este diferita (tabelul nr. 1). De asemenea este diferită şi apartenenţa taxonomica a microorganismelor care se dezvoltă pe aceeaşi scena, în funcţie de condiţiile de microclimat şi de nutrienţii disponibili.

 

Tabelul nr. 1   Apartenenţa taxonomică şi distribuţia numerică a fun­gilor pe frescele Sf. Augustin şi Sf. Jerome

 

Specii

Unităţi formatoare de colonii (UFC)

fresca Sf. Augustin

fresca Sf. Jerome

Aspergillus flavus

-

3

Aspergillus sydowi

-

2

Aspergillus versicolor

-

660

Aspergillus sydowi Aspergillus versicolor

-

1

Aspergillus sp.

-

2

Botrytis cinerea

1

2

Cladosorium cladosporioides

74

-

Cladosorium sphaerospermum

3

204

Coniothyrium cerealis

-

1

Engyodontium sp.

1

-

Oidiodendron cerealis

2

-

Penicillium brevi-compactum

340

-

Penicillium chrysogenum

-

3

Penicillium meleagrinum

1

-

Penicillium notatum

-

1

Penicillium purpurogenum

100

-

Penicillium rugulosum

13

2

Penicillium variabile

18

8

Trichoderma harzianum

2

1

 

Decontaminarea cu agenţi fizici

Operele de artă pot fi decontaminate prin tratament cu radiaţii gamma sau fascicule laser. Literatura de specialitate recomandă folosirea radiaţiilor gamma pentru distrugerea insectelor xilofage şi a fungilor din structura obiectelor din lemn (icoane, mobilier, sculpturi) şi a documentelor. În ultimul caz se constată îngălbenirea substratului.

 

EXPERIMENTE, MATERIALE ŞI METODE

Au fost realizate mai multe experimente în care s-a testat eficienţa mai mul­tor lungimi de undă.

Un prin experiment a utilizat radiaţia emisă de un laser cu azot. Au fost ex­puse iradierii trei tulpini aparţinând genurilor Alternaria, Ulocladium şi Chaetomium. La baza acestei decizii au stat următoarele considerente:

·  tulpinile au fost izolate de pe o pictură murală aflată în Sighişoara;

·  în probele recoltate au avut frecvenţa cea mai mare;

·  sunt întâlnite frecvent pe picturi murale din biserici;

·  Alternaria şi Ulocladium sintetizează pigmenţi melanici cu rol protector faţă de radiaţii;

·  Chaetomium formează periteci şi pigment verde care conferă de asemenea rezistenţa faţă de radiaţii.

 

S-au expus iradierii următoarele variante:

·  Spori şi hife recoltate prin tehnica amprentei pe o bandă adezivă transpa­rentă;

·  Fragmente de culturi (spori şi hife) dezvoltate pe mediul nutritiv (cartof-glucoză-agar).

S-au folosit două nivele de energii E1 = 0.09 mJ/cm2 (U=5kV) şi E2=0.2 mJ/cm2  (U=7,5kV) şi un număr variabil de pulsuri (10; 50; 100; 200) în cazul iradierii benzilor adezive şi un numar fix de pulsuri (200) în cazul culturilor.

S-au iradiat 24 probe pentru cele trei tulpini dispuse pe benzi adezive co­res­punzând la câte 4 probe pentru fiecare energie. În cazul culturilor s-au iradiat 6 probe (câte una pentru fiecare energie, corespunzător celor trei culturi). Fascicu­lul provine de la un laser cu azot molecular a cărei lungime de undă este de  332,1 nm.

După iradiere materialul expus a fost menţinut la întuneric pentru a preîntâmpina fotoreactivarea.

În laboratorul de microbiologie materialul biologic a fost prelucrat pentru determinarea ratei de supravieţuire. Raportarea s-a făcut la materialul neiradiat.

Probele martor (neiradiate) au fost prelucrate prin metoda diluţiilor seriate şi au fost inoculate pentru determinarea concentraţiei totale a unităţilor formatoare de colonii.

Probele iradiate au fost de asemenea prelucrate prin metoda diluţiilor seriate şi au fost inoculate pentru determinarea concentraţiei unităţilor formatoare de colonii rămase viabile.

Viabilitatea a fost determinată aplicând următoarea formulă:

 

               Nr. ufc în proba martor - Nr. ufc în proba iradiată

      V = 

                                                 100

 

 

Rezultate şi discuţii

Viabilitatea sporilor (ufc unităţi formatoare de cultură) este afectată diferit în funcţie de genul fungic şi de nivelul energiei. Astfel, sporii de Alternaria au fost cei mai sensibili, iar cei de Chaetomium cei mai rezistenţi.

Nivelul cel mai mare de energie E2=0.2 mJ/cm2 (=7,5kV) a fasciculului la­ser a determinat menţinerea unei viabilităţi ridicate a sporilor de Ulocladium (aproximativ 90%). Rata redusă a mortalităţi ne determină să sugeram creşterea energiei, a numărului de pulsuri sau folosirea unui alt tip de laser.

Nivelul mai mic de energie E1 = 0.09 mJ/cm2 (U=5kV)  nu afectează via­bi­litatea sporilor de Ulocladium indiferent de numărul de pulsuri. Semnalăm apariţia unor mutante modificate morfologic prin iradierea cu E2=0.2 mJ/cm2  (U=7,5kV)  în 200 pulsuri.

În cazul sporilor de Alternaria energia E2=0.2 mJ/cm2 (U=7,5kV) aplicată în regimuri diferite, de la 10 la 200 de pulsuri, a determinat o reducere a viabilităţii (aproximativ 70%).

Energia E1 = 0.09 mJ/cm2 (U=5kV) aplicata în 10-200 pulsuri nu a afectat viabilitatea sporilor de Alternaria.

 

Tabelul nr. 2  Tipuri morfologice de deteriorare a picturii murale

 

Tip morfologic

Unităţi forma­toare de colonii

Specia fungică

Gen/tip de bacterii

Pete alb gălbui, negre pe stratul pictural

1.0x106

Cladosporium sphaerosperum

Geomyces pannorum

Verticillium lamellicola

Beauveria bassiana

Artobacter sp.

Streptomyces sp.

Nytrying bacteria

Bacillus sp.

Pete brun-negri­cioase pe tencuială

2.5x104

Cladosporium sphaerosperum

Geomyces pannorum

Verticillium lamellicola

Beauveria bassiana

Tritirachium album

Artobacter sp

Streptomyces sp.

Bacillus sp.

Nytrying bacteria

 

Pulverulenţă la suprafaţa cărămi­zilor

4.9x105

Phalophora sp.

Acrodontrum crate­riforme

Cladosporium sphaerosperum

Verticillium lamellicola

Fusidium viride

Tritirachium album

Artobacter sp

Streptomyces sp.

Nytrying bacteria

 

Pulverulenţă la suprafaţa pietrei de construcţie

1.5x105

Tritirachium album

Beauveria bassiana

Cladosporium sphaerosperum

Artobacter sp

Streptomyces sp.

Nytrying bacteria

Brevibacterium sp.

 

Tabelul nr. 3  Viabilitatea sporilor de Alternaria iradiaţi cu laser cu azot molecular

 

Fluenta laser

Nr. pulsuri

Viabilitatea

E2=0.2 mJ/cm2 

 

10

75

50

80

100

60

200

81

E1 = 0.09 mJ/cm2

10

100

50

100

100

100

200

100

E2=0.2 mJ/cm2  *

200

100

E1 = 0.09 mJ/cm2 *

200

100

* = cultură iradiată

 

Semnalăm de asemenea aparitia unor mutante modificate morfologic prin iradierea cu E2=0.2 mJ/cm2  (U=7,5kV) cu 200 de pulsuri. Sporii de Chaeto­mium nu au fost afectaţi de iradierea cu laser cu azot molecular indiferent de energia şi pulsurile aplicate. Nu au fost semnalate mutante modificate mor­fologic.

Apariţia formelor mutante demonstrează efectul laserului cu N2 asupra mate­rialului genetic (ADN). În stadiul actual al cercetărilor nu ne putem pronunţa asupra capacităţii acestor mutante de a coloniza pictura murală.

 

Al doilea experiment important a utilizat două surse de radiaţie cu emisii în domenii relativ depărtate: 404 nm şi 407 nm linii spectrale obţinute prin filtrarea fasciculului emis de lampa cu Hg; respectiv prima armonică a laserului cu mediu activ solid YAG:Nd (532nm).

Menţionăm că efectul fasciculului la 532 nm (de culoare verde) a fost consi­derat interesant deoarece acest tip de radiaţie este des experimentat şi recoman­dat în tehnicile laser de curtare a obiectelor de arta, deoarece induce o îngălbenire specifică a substratului mult mai mică decât la aplicarea regi­mului fundamental (1064 nm).

Tulpina Chaetonium sp. este sensibilă la 404-407 nm. Viabilitatea a scă­zut de la 15% (iradiere timp de 5') la 9% (iradiere timp de 15'). Tulpina de Cladosporium sp. este mai puţin sensibilă. Viabilitatea scade la 90% (iradiere timp de 5') la 88% (iradiere 15').

Iradierea cu YAG-Nd a fost mai puţin eficientă decât cea cu Hg. La Cla­dosporium sp. s-a redus viabilitatea de la 86% iar la Chaetonium sp. la 60%.

 

ANALIZA STABILITATII CARACTERISTICILOR CROMATICE ALE MATERIALELOR POLICROME ÎN URMA IRADIERII

 

În experimentele celei de-a doua faze a studiului s-a urmărit determinarea eventualelor alterări cromatice ale substratului. Suprafeţele policrome, sunt se pare cele mai sensibile la acest tip de radiaţie, de aceea în paralel cu studiul decontaminării formaţiunilor biologice s-au testat o serie de probe de culoare diferite ca pigment şi liant. Pentru o analiză obiectivă şi eficientă s-au propus condiţii experimentale nefavorabile, mai exact  s-a ales o serie de pigmenţi sensi­bili la lumină. Pentru probele de tempera s-au ales pigmenţi care nu au rezistenţă în tehnica a fresco.

 

Foto 1.  Probe de tempera aplicate pe suport lemnos.

CULORI TEMPERA – Culorile tempera (cu emulsie de ou) au fost aplicate pe un suport de lemn cu preparaţie de praf de cretă + clei de oase şi pe suport de var cu câlţi (aplicaţi după uscarea acestuia).

Au fost analizate următoarele materiale: alb de plumb (2PbCO3); galben de crom (PbCrO4); roşu cinabru (HgS) – Foto 2 - a; roşu de natură organică este un colorant de tip antrachinonic; verde de cupru (verdigris); albastru de Prusia – pigment sintetic, ferocianură ferică Fe4[Fe(CN)6]3.

CULORI A FRESCO – Culorile a fresco au fost aplicate pe un suport de var + câlţi.

Miniu  (Pb3O4); Massicot  (PbO); albastru smal – silicat de cobalt şi pota­siu; albastru ultramarin – este un silicoaluminat de sodiu – Foto 1, 2 - a, b; cromat de zinc (ZnCrO4); cinabru.

CULORI ACRILICE: Ocru galben; verde Paolo Veronese, negru mars; alb de titan.

CULORI ALCHIDICE: Alb de zinc, ocru galben deschis; roşu de cad-miu, verde Paolo Veronese, negru ivoriu.

 

Probele de culoare au fost iradiate în condiţii identice cu  cele în care s-au iradiat probele biologice (laser pulsat cu azot N2, lampa cu vapori de Hg, Laser cu YAG:Nd – prima armonică).

Imaginile de mai jos ilustrează zone iradiate (zona inferioară) cu zona martor (zona superioara) care nu a fost expusa radiaţiei UV.

 

 

 Foto 2. Exemplu de probă analizată - Roşu cinabru, grosisment 60x (foto a), diagramele reflectantei înainte şi după iradiere pentru alb de Titan - acrilic (foto b)

 

 

Foto 3.  Probe de culoare aplicate pe suport var + câlţi; tehnica a fresco – dreapta  ima­ginii / tehnica a secco – zona stângă a imaginii.

 

 

 Interpretarea rezultatelor se face prin analiză vizuală – una dintre metodele de bază ale restaurării pentru ca oferă informaţii maxime din punct de vedere al esteticii suprafeţei tratate – şi prin reflectometrie. În diagrama alăturată sunt  prezentate comparativ valorile reflectantei în domeniul vizibil pentru o probă înainte şi după iradiere. Suprapunerea completă a celor două diagrame demonstrează – după cum era şi de dorit – ca valorile cromatice ale probei nu s-au modificat după iradiere. Toate probele menţionate, supuse la tratamentele cu mai multe variabile (lungime de undă, fluenţă laser, durata tratamentului) au dat rezultate similare – foto. 2,b [1,2,3]. În concluzie, tratamentele în limitele parame­trilor menţionaţi pentru decontaminare nu prezintă riscuri în privinţa conservării culorilor substratului.

 

UVLAS – ECHIPAMENT CU DIODA LASER UV

Conform rezultatelor de laborator, lungimea de undă cu eficienţă maximă în ceea ce priveşte scăderea viabilităţii biofilmelor este cea înscrisă în domeniul 404–407 nm. Pentru construirea unui echipament care să exploateze această proprietate, dar care să fie portabil, să asigure o fluenţă satisfăcătoare şi care să aibă un fascicul bine direcţionat astfel încât să nu se aplice expunerii necontrolate pe zone învecinate celor de interes s-a  selecţionat dioda laser UV care emite un fascicul stabil cu lungimea de unda 405 nm. Comanda diodei laser se face cu ajutorul unei surse de alimentare şi comanda cu microcontroller (foto 4).

 

           Foto.  4

 

Programul permite selectarea duratei de iradiere, fluenţa laser aplicată şi alţi parametrii funcţionali. Opţional datele se pot insera într-o bază de date digitală alcătuită din fişe de restaurare.

 

 

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Innovative science applications for Cultural Heritage preservation

 

 

Roxana RADVAN

 

National Institute of Research & Development for Optoelectronics INOE

Center for Restoration by Optoelectronical Techniques CERTO

Platforma Magurele, P.O.Box MG 5, Bucharest, Romania

e-mail: radvan@inoe.inoe.ro, web page: http://inoe.inoe.ro/certo

 

 

 

 

 

 

National Institute of Research and Development for Optoelectronics – INOE (http://inoe.inoe.ro) was organized in 1996 in concordance with new European research drifts. Beneficiary of the modern and flexible management of the insti­tute, Department of Advanced methods and techniques for restora­tion & conser­vation successfully applied the accumulated experience in laser design and laser application, non-conventional technologies and optoelec­tronical device design. Due to its performances and their annual increasing, this department was attested by national competition as centre of excellence – Centre for Restoration by Optoelectronical Techniques – CERTO (http://inoe.inoe.ro/certo). Since 2002, unanimously approved as leader in its field of activity, CERTO is coordinator of PRO RESTAURO – a national thematic network for advanced research results implementation in concrete applications (http://inoe.inoe.ro/prorestauro). First Eureka project with Ro­manian coordination was elaborated by INOE-CERTO specialists (E!2094 CLEANART  – with application in artwork restoration), also first  COST Action initiated by Romania – COST G7 „Artwork Conservation by Laser” was promoted by the same group.

The developed activities are focused on:

i) optoelectronical independent or associated methods and equipments for clean­ing (especially for small and delicate pieces, jewellery etc.):

-   laser cleaning high-precision techniques – through optical microscopy and with various accesories (aiming system, digital image capture and process recording, information storage in dedicated database);

-   ultrasound techniques and methods;

ii) imagery and image composition analysis

- high-resolution multispectral image analysis,

- analitic models for image interpretation in visual arts;

 iii) microclimate control, air quality evaluation and environmental stress impact on  artefacts:

- microclimate monitoring and air quality evaluation in museums

and galleries;

- laser remote sensing for environment control.

All applications have since different stages stored experimental result in data­bases.

The diagnostic/technical resources available to CERTO:

§   High resolution multispectral camera ARTIST (IART INNOVATION product);

§   Optical microscopes for laser operations on 2D objects –MicroLASER x-y;

§   Optical microscopes for laser operations on 3D objects –

   MicroLASER x-y -z (portable);

§   ARTIST camera software

 

PRO RESTAURO- NATIONAL THEMATIC NETWORK joins several institutions:

·   National Art University from Bucharest, Department of Restoration;

·   National Museum of History and Archaeology from Constanta;

·   National Museum of Art from Craiova;

·   Institute of Art History from Romanian Academy of Science;

·   Institute of Etnography and Folklore from Romanian Academy of

   Science;

·   Institute of Biology from Romanian Academy of Science;

·   Institute of Analytic Instrumentation – Cluj Napoca;

·   Centre for Environment Protection and Consultancy-“Politehnica”

   University from Bucharest,

·   HAR Foundation.

 

The paper presents significant result in main advanced on-going projects:

 

 

 

 

 

 

 

Microclimate conditions and systems for museums, galleries, archives

 

Study of case to Bran Castle

 

 

Roxana Radvan*

Roxana Savastru*

Cristian Deciu*

Walter Maracineanu*

Ioana Gomoiu**

Dan Mohanu***

 

 

 

 

The study is about the assessment of pollution damage and evaluation the costs and benefits of conservation approaches in one of the most important Romanian historical site – Bran Castle. One of the very important challenges that arose is the need to integrate and correlate environment conditions and induced damages. For an efficient conservation plan it is necessary to know how envi­ronmental pollution, relative humidity and temperature generated damages to cultural heritage.

Nitrogen dioxide, sulphur dioxide, ozone, hydrogen sulphide and carbonyl sulphide are the main damage-causing gases present outdoors. Their tolerate values are indicated by several European standards. They come mainly from fuel burning in transport, buildings and industry. Biological processes, through the decay of organic matter, also generate the sulphides. SO2 tar­nishes metals, dam­ages paints and dyes, discolours papers, reduces strength of textiles, attacks photographic materials.

Much of the nitrogen dioxide and ozone is not formed directly, but is the product of secondary reactions involving the action of sunlight on pollutants.

Nitrogen dioxide from gas stoves, and hydrogen sulphide as a bioeffluent from people (visitors) and from some interior decorative materials and mu­seum objects themselves, such as zoological specimens and organic material, espe­cially from waterlogged sites. Nitrogen dioxide induces fading in textile dyes, reduces strength of textiles and damages photographic film. Photocopi­ers and laser printers, particularly older ones can also give off ozone.

Ozone and nitrogen oxide in the same room - unfortunately already con­sid­ered “ordinary” pollutants – generate the formation of nitric acid and other reac­tive secondary products. Pigments and their derivates (tempera and oil colors), natural mediums (egg emulsions and linseed oil), as well as acrylics and alkyds paints often absorb ozone and degrade the artwork surface [1].  Ozone cracks rubber, induces fading in dyes, and attacks photographic mate­rials and damages books.

Also important demonstrated conclusions of several European projects indi­cates that:

-   the main effect of air pollution on hydraulic mortars is gypsum formation, measured also as soluble sulphate;

-   the presence of gypsum in hydraulic mortars produces two secondary dam­aging products ettringite and thaumasite , measured also as insoluble sul­phate;

-   the ettringite formation depends by material composition (aluminium con­tent).

-   the thaumasite formation is controlled by SO2 concentration and by atmos­pheric parameters.

Among high spread pollutants, SO2 is one of the main pollutant agent dam­aging hydraulic mortars, which turn out to be most sensitive building materi­als because of the formation of primary and secondary damage products. Although having important implications on the development of conservation strategies for monuments and historic buildings, this result is also of great relevance to the built environment as a whole. [2]

The temperature is a very important factor in conservation of artifacts, as changes of this parameter induce differential expansions in the materials and tensile strength between the top layer and undersurface structure. Tempera­ture cycles accelerate fatigue failure in delicate materials.  The surface of the artwork is first affected and rapidly blasted. In stone’s casuistry, thermal cy­cles cause mechanical desegregation of the outer region of stones. The water activity is always superimposed to the mechanisms of temperature degrada­tion. The air temperature is a key factor in determining the habitat for bio­logical life and in their metabolism control [z]. The metabolic processes are reduced when the temperature is bellow 200C. Favorable conditions for microbiological processes are between 200C and 350C.

EXPERIMENTAL SET-UP

Metrological sensors network contains 30 double (for temperature and RH) data logger sensors model TP120.  Experimental data are analytical and graphical processed by sensors’ own software and by Lab View software.

Each sensor has own battery that warrants 5 years autonomy. Tempera­ture range is between -400C and +800C, sensibility 0.1 0C, and HR range is between 0% and 95 % RH, sensibility 2% for RH. Storage capacity is over 32512 records. Response time of the sensor is 10 minutes for 63% of the entire scale. Full data­base transfer time is maximum 3 minutes.

 

Figure 1 shows the block scheme of the monitoring system.

 

Figure 2 shows the program screen: it contains comparative diagrams with computed average values, with individual sensors’ values, with selected values by position criteria etc.

 

The main controlled points are distributed in various places:

-   the top of the Castle – outside;

-   in the indoor yard – in free space;

-   at the first level – in painted chapel, in solders’ dinning room, in the room from the basement of the round tower;

-   At the second floor  - in he jail;

-   at the next floor – in neo-brancovenesc style room ; in gothic room, in coun­cil room, in Queen Elisabeth’s bedroom;

-   at the upper floor – in Biedermeier room, in King Ferdinand’s room, in  neo-baroque style room, in Spanish room and in queen’s music room.

A particularly attention was given in Chapel. It is a round room complete covered by large wall painting affected by humidity, by temperature very significant variations and by microbiological attack. Such a space must be rigorously con­trolled in several points of extreme conditions.

 

 

Photo 1 shows the collection of biological sample from the Chapel.

Photo 2 – The sensors were fixed in the most critical areas of the selected chambers.

 

Sensors network in this room control highest point (next to Jesus Pantocrator icon), window area, door area, a very bottom point on the opposite wall in front of the window and in front of the door, half height of the same wall – point with maximum natural illumination.

 

CONCLUSIONS

The collection of the Bran Castle contains various art objects and histori­cal documents. The condition of ancient documents and books preservation in this museum are very difficult to be ensured. Because of them, the main part of the collection is stoned in different buildings of the museum complex. The violent variations of humidity and temperatures are dangerous to all art objects, but the impropriate light mainly affects paper and leather objects. The display cases, because of the strait space, are located close to the windows and that affects seriously the exposed documents through fading processes. Among those docu­ments there are some which testify the importance of Bran Castle in the political and economic life of this zone, therefore the importance of their proper conser­vation “Casa de ceai” (Tea House), “Inima reginei” (Queen`s hart”) and “Vama” (The Customs House) are other three small buildings in the museum`s park. In these spaces are deposited the most sensi­ble documents and objects from the museum`s patrimony.

The on-going project has preliminary results, which consisting in deter­mina­tion of the risks sources and main urgent measures for degradation stopping. The design network of sensors and dedicated software respect general restrictions and European standard rules and guidelines for microcli­mate control in museums, archives and galleries.

The present stage of the project is focused on the construction of a smart monitoring system. The number of sensors and input data is in continuous in­creasing and due to LabView facilities ad-hoc function of risk evaluation can be ordered. One of the first functions is to pre-signal limit values exceed.

In spite of the artwork or ancient building dimensions – impressive or very fine – each restoration case must start with few obligatory steps:

-   intimation of the existing risk and its mechanism of deterioration;

-   definition of the involved material acting, of the artwork techniques influ­ence in the deterioration process,  and microclimate conditions role;

-   construction of a precise system for material/environment stability.

Obviously, optomechanical and optoelectronical equipment are most suit­able groups of techniques for this sort of applications. They can assure non-contact methods or less destructive precise control systems for on-line envi­ronment control and for real-time control of the artwork response to the microclimate stress.            

 

 

 

 

 

 

 

 

COST ACTION G7 “ARTWORK CONSERVATION BY LASER” –

A PAN-EUROPEAN STRUCTURE FOR A MODERN PROVOCATIVE DOMAIN

 

 

 

Roxana RADVAN

 

 

 

 

 

COST – European Cooperation for Science and Technology is a coopera­tive framework maintained by European countries since 1971. In 1995, the COST family comprises 25 states as well as the European Commission. COST coop­eration is thus essentially based on direct interaction between research teams in Europe, but the cooperation is supported and backed up by the Governments of the participating countries.

Recently, a multidisciplinary approach of study and preservation aspects of Cultural Heritage has created the new Interdisciplinary field of Artwork Conser­vation by Laser. 

By combining the advances of laser technology - science and applications – with the modern conservation science, the field aims at scientific and tech­nologi­cal benefits.

COST G7 is one of the on-going action started mid 1999 and includes dele­gates from 20 countries (Austria, Belgium, Cyprus, Denmark, France Finland, Germany, Greece, Hungary, Italy, Latvia, Malta, The Netherlands, Norway, Poland, Portugal, Romania, Slovenia, Spain, United Kingdom).

 

 

COST ACTION’S MAIN AREAS

Laser-based techniques offer many unique possibilities for the examina­tion and conservation of artworks. The laser is a modern, highly controllable and versatile tool.

COST Action G7 has been set up to address challenges in three main ar­eas- working groups:

(i)      Laser systems for investigation and diagnosis;

(ii)    Laser systems for real-time monitoring of environmental pollution;

(iii)   Laser Systems for cleaning applications.

A very important contribution of this COST Action is to the prevention of cultural heritage deterioration: work on developing techniques for monitoring the quality of indoor and outdoor atmospheres is proposed in parallel with restoration and conservation work.

It is counter- productive to spend a great deal of effort in restoration and con­servation without taking action to minimize the risks of future damage to the artwork. The partners’ profiles present the skills and expertise available to this COST action.

The first working group embraces research, training aspects and other ac­tivi­ties related to laser cleaning, the most widely known application in the field. It is composed of representatives of 41 Institutions. The members have several back­grounds:

(i)               Physicists, Chemists, Biologists and Engineers performing fundamen­tal and applied research on laser cleaning systems and laser-matter interac­tions on diverse substrates: paper, parchment, stone, canvas and mural paint­ings, glass, ceramics and metals;

(ii)              Conservation scientist & Conservators specialized in the pre-quated materi­als;

(iii)            Laser Manufacture & Equipment companies.  

The second working group (33 Institutions from 19 COST Countries) per­forms both fundamental and applied research on Laser and Optical tech­niques, systems and protocols for analysis and diagnostics of works of art and related activities (conservation, display, cataloguing).

Fundamental research is largely devoted to the investigation of the poten­tial of laser spectroscopic techniques (laser-induced fluorescence, LIF; laser-induced-breakdown spectroscopy, LIBS; Raman and Infrared spectroscopy) as tools for the characterization of materials (e.g. LIF for pigments, binding media, var­nishes; LIBS for pigments, stratigraphic analysis, on-line monitor­ing). Other laser-based techniques (3-D scanning, holography, holographic interferometry,

Doppler vibrometry, fluorescence imaging either spectrum- or time-re­solved or both), non-laser related optical techniques (diffuse-reflectance spectroscopy, colorimetry), and techniques borrowed from other fields, such as nuclear physics, are the subject of basic research investigating their poten­tial for the characteriza­tion of processes (ageing, restoration, ablation, weath­ering, structural alteration etc.).

The most developed applied research activities are related to the moni­toring of various conservation procedures including laser-assisted and tradi­tional cleaning applications.

Early detection of defects and damage is also carried out by a number of groups. These applications already concern real artifacts and valuable objects. Nevertheless the WG2 members have agreed to undertake a specific task on development and validation of protocols for structural defect diagnosis, for in situ chemical analysis and for analytical methodology before any intervention on artworks, facades and buildings.

The third working group covers the existing gaps in research on environ­mental aspects (e.g. continuous monitoring of pollution and/or light levels) in relation to their specific effects on the art pieces. The significance of the ac­tion lies on the unique multidisciplinary approach towards the common goal of the preservation of Cultural heritage.

The remit of this working group includes the evaluation of current meas­ure­ment techniques available for the monitoring/characterization of an art­work and its environment. Such techniques have many applications including: (i) charac­terization of the state of an artwork prior to intervention (thereby allowing choice of the most appropriate form of treatment), (ii) characteriza­tion of the response of an artwork to its environment under different weath­ering conditions and (iii) on-line process (cleaning) control.

The main focus of WG3 is exploitation of advances in laser and electro-optic technologies for development of cost-effective and non-invasive in situ environ­mental monitoring instruments. These will allow fast, accurate moni­toring of the local environment to which an artwork is exposed, thereby ena­bling detailed study of the effect of various environmental parameters on the artwork and the causes of deterioration.

 

 

ARTWORK CONSERVATION BY LASER IN EUROPE DATABASE

A database containing information on publications, laser cleaning sys­tems, laser and optical methods for monitoring, analysis and diagnostics, and future demands for research in the field is available for downloading at http://alpha1.infim.ro/cost .

The purpose of the database is to collect together important information from the field of lasers and optical methods in conservation so that it becomes easily accessible to people working in the field. This work is part of the Euro­pean Co-operation in the field of Scientific and Technical Research (COST) Program of the European Commission: COST Action G7 ‘Artwork Conser­vation by Laser’.

The database has following main sectors:

Task 1 - a bibliographic database containing information on publications in the field;

Task 2a  - contains information on all conservation laser cleaning systems manufactured in Europe. This includes commercially available systems, pro­totype systems and systems in institutions where access and expertise can be made available through collaborative projects.

Task 2b - This contains information on laser and optically based tech­niques suitable for environmental monitoring, analysis and diagnostics of artworks.

Task 3 - This is a database containing information on the future de­mands for research in the field of COST Action G7.

 

 

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* Institutul Naţional de Cercetare Dezvoltare pentru Optoelectronică  INOE, Centrul pentru Restaurare cu Tehnici Optoelectronice CERTO

Platforma Magurele, P.O.Box MG 5, Bucharest, Romania e-mail: radvan@inoe.inoe.ro, web page: http://inoe.inoe.ro

** Institutul pentru  Biologie – Academia Româna de Ştiinţe

*** Universitatea de Atre Bucureşti - Depart. Restaurare Conservare

 

 

* National Institute of Research & Development for Optoelectronics INOE, Centre for Restoration by Optoelectronical Techniques CERTO

** Institute of Biology - Romanian Academy of Science

*** University of Arts from Bucharest - Dept. Restoration & Conservation