Rescat 38 ENGLISH

38

YEAR 2021 EDITORIAL

Conservation plan of archaeological ensemble of Tarraco Page 2

INTERVIEW

José Luis Prada Pérez Page 3

INNOVATION & RESEARCH

The National Archaeological Museum of Tarragona Page 10

The roman villa of Els Munts Historical and archaeological context 20 Conservation-restoration interventions 30 Preventive conservation plan 34 Previous studies of the mural paintings 46 The cryptoportico 52 The southern baths 54 The antechamber of the Mithraeum 58 Consolidation of la Tartana 60 The large cistern 64 The ceiling - discovery 68 The ceiling preliminary study 14

INNOVATION & RESEARCH

ROMAN VILLA OF ELS MUNTS

Index

2

Centre de Restauració de Béns Mobles de Catalunya

EDITORIAL

CONSERVATION PLAN OF THE ARCHAEOLOGICAL ENSEMBLE OF TÀRRACO The Archaeological Ensemble of Tàrraco encompasses 14 Roman monuments located in the city of Tarragona and the county of El Tarragonès. It was protected as an asset of national cultural interest in 1966, and in 2000 the ensemble was declared a UNESCO Human Heritage Site (Ref. 875) in the category of cultural site. This declaration points out that the archaeological remains meet the following criteria: To exhibit an important interchange of human values, over a span of time or within a cultural area of the world, on developments in architecture or technology, monumental arts, town-planning or landscape design.

The Roman remains of Tàrraco are of exceptional importance in the development of Roman urban planning and design and served as the model for provincial capitals elsewhere in the Roman world.

To bear a unique or at least exceptional testimony to a cultural tradition or to a civilization which is living or which has disappeared. Tàrraco provides eloquent and unparalleled testimony to a significant stage in the history of the Mediterranean lands in antiquity.

The cultural value attached to the Archaeology Ensemble of Tàrraco required a conservation plan that considered what was needed in order to properly conserve the ensemble, one that could detect the urgent needs and, in short, could assert the need for the administrations’ commitment to plan the resources needed to conserve and restore this invaluable heritage. Accordingly, in 2015 the CRBMC promoted and led a Conservation Plan that developed a diagnosis and laid out in general terms the actions needed for each of the monuments, without going so far as to draw up the specific executive projects.

RESCAT

As a result of the diagnosis, three levels of urgency were established: very urgent, urgent or not urgent, based on the degree of alteration determined by different parameters related to the instability of the materials with which they are made, such as breakages and deformations; separations and detachments; material losses; surface alterations; biological colonisation; and the effects and appropriateness of previous interventions, among other parameters. An approximate economic valuation was made of each monument drawing from previous studies and the development of the project.

Pere Rovira, Aleix Barberà and the company Arcovaleno Restauro, SL, participated in developing the Plan. The Plan does not address the structural or architectural elements or possible archaeological interventions. The Architectural Heritage Service later released another document diagnosing the needs, which specifically addresses architectural aspects.

The two plans complement one another.

In this Rescat newsletter, we wanted to highlight the work undertaken in recent years in the Roman villa of Els Munts, yet it is also important to note that interventions are underway in other monuments and sites in the archaeological ensemble as well, always in accordance with the National Archaeology Museum of Tarragona (MNAT) and the Tarragona Town Hall when the monuments or sites are associated with the municipal administration. On the other hand, it is also important to highlight the coordination with other units within the Department of Culture, such as the Sub-directorate of Architectural, Archaeological and Palaeontological Heritage. Àngels Solé, director of the CRBMC

INTERVIEW

Ruth Sadurní Codina, holds a Bachelor’s in Chemistry from the Autonomous University of Barcelona (UAB) and a diploma in Conservation and Restoration from the Escola Superior de Conservació i Restauració de Béns Culturals de Catalunya (ESCRBCC) in the Archaeology specialisation.

Photo: Escola Superior de Conservació i Restauració de Béns Culturals de Catalunya (ESCRBCC)

JOSÉ LUIS PRADA PÉREZ He was born in Barcelona in 1954 and has had an extensive career in the fields of teaching, research and scientific consulting in a variety of conservation and restoration projects. He was present at the formation of the Escola Superior de Conservació i Restauració de Béns Culturals de Catalunya (Advanced Studies in Conservation and Restoration of Cultural Heritage of Catalonia) (ESCRBCC) from 1991 until he retired in 2020. In 1995, he finished his doctoral thesis at the University of Oviedo on monument conservation, directed by Rosa Maria Esbert, and he later joined a research group at the Autonomous University of Barcelona (UAB) led by Aureli Álvarez. He participated as a researcher in European projects on building materials and innovations within monument conservation in the Eduardo Torroja Institute for Construction Sciences, which is part of the Spanish National Research Council (CSIC). Between 2001 and 2004, he was an associate professor in the Department of Minerology and Crystallography at the UAB.

JOSÉ LUIS PRADA PÉREZ: 30 YEARS DEDICATED TO TEACHING AND RESEARCH IN THE CONSERVATION OF THE CULTURAL HERITAGE PHD IN GEOLOGICAL SCIENCES FROM THE UNIVERSITY OF BARCELONA, PROFESSOR AT THE ESCRBCC AND ASSOCIATE PROFESSOR AT THE UAB. HE HAS SERVED AS A CONSULTANT ON CONSERVATION AND RESTORATION PROJECTS FOR UNESCO; ON CATALOGUING ARCHAEOLOGICAL SPACES AND DECLARATIONS OF HUMAN HERITAGE SITES; AND ON THE STONE SPHERES OF COSTA RICA (2014), A GROUP OF MORE THAN 500 PETROSPHERES MOSTLY LOCATED IN SOUTHERN COSTA RICA ON THE ALLUVIAL PLAIN OF THE DELTA OF THE DIQUÍS RIVER. HE HAS ALSO SERVED AS A SCIENTIFIC CONSULTANT ON OTHER PROJECTS SUCH AS SANT PAU DEL CAMP CHURCH AND THE MONUMENT IN PLAÇA D’ESPANYA IN BARCELONA AND THE WALL IN LLEIDA. IN TARRAGONA, HE WORKED AS THE SCIENTIFIC DIRECTOR OF RESTORATION PROJECTS, SUCH AS THE ARC DE BERÀ, THE MÈDOL QUARRY AND THE AQUEDUCT AND WALL OF TARRAGONA. HE ALSO DIRECTED THE DOCTORAL THESES OF MANUEL IGLESIAS, NÚRIA GUASCH AND LUZ POCOSTALES IN THE FIELD OF CONSERVATION AND RESTORATION. José Luis, can you tell us a bit about how a geologist became involved in the field of cultural heritage?

Everything started with a class taught by Rosa Esbert on monument conservation. She was the first person to encourage me to do this kind of thesis. This field fit in with two things that were very important to me personally: first, the humanities, a topic that I got from my mother, who was

centrederestauracio.gencat.cat

educated in philosophy and the humanities and adored the heritage and culture, and secondly the scientific side.

What led you to teach classes at the Escola Superior de Conservació i Restauració de Béns Culturals de Catalunya?

It happened while I was working as a consultant on the monument in Plaça d’Espanya (Barcelona). There,

RESCAT

3

Index

4

Centre de Restauració de Béns Mobles de Catalunya

—

Maya mask made in pozzolanic mortar of flint.

Tikal (Guatemala). Photo: José Luis Prada

—

I received the proposals to make a service commission for the ESCRBCC. At first, I started almost as a restorer, and the first classes I taught were on restoration materials.

After a few years, Xavier Figueras, then the director of the school, along with the partner were able to assign me a more appropriate commission, namely as professor of Natural Sciences, Geology and Biology. That special job, which no longer exists, enabled me to join the school as a professor on a service commission.

After all these years teaching classes at the school, what stands out the most to you?

The most important thing is that together we all created a professional that didn’t use to exist, because at that time conservation and restoration were still a speciality within the Fine Arts Faculty of Barcelona. It was also taught in the School of the Provincial Council. Still, there was no professional with a real profile devoted exclusively to heritage conservation with multidisciplinary knowledge that included three fields (restoration, humanities and science). This enabled a series of schools to be created around Spain with the help of the Escola Superior de Conservació i Restauració de Béns Culturals de Madrid (ESCRBC). I am very satisfied to have been able to participate in creating a new job profile of conservator-restorer of cultural heritage which is important to today in the conservation and restoration of the heritage.

RESCAT

—

Electronic Microscope Services at the Fine Arts and Design Faculty at the Technology Institute of Athens (https://www. uniwa.gr/) during an Erasmus stay for professors. Photo: Joan Escudé

—

How would you rate scientific education in conservation and restoration, and where should it be headed?

I believe it is one of the mainstays. I worked on a European project to create a Master’s in Scientific Conservation, in which different branches of the sciences participate, with the goal of training science professionals who could serve as consultants and members of major treatment projects as well as research projects. The profile of the scientistconservator was being debated at that time, while the Master’s was being created. The idea was that two professionals are needed, who should not be confused with each other: first is the science that a conservatorrestorer trained in the schools and faculties has to know, and second is the scientist-conservator, who uses their science training to gain enough humanistic and interdisciplinary information to consult in the field of conservation and restoration. I can say that the former has now been developed all over Europe, while the latter is not yet sufficiently entrenched.

How would you rate the interdisciplinary nature and education between scientists and the cultural heritage today?

There’s still a lot of work ahead. It’s one of the aspects which we discussed while creating the Master’s with Matteini and other researchers. What he mainly saw was that scientists were very attached to universities, laboratories and projects. Scientists have to climb the scaffolding, go to the work and archaeology site in order to participate and talk with the rest of the team. All of this makes the profile of the scientist-conservator someone who needs continuous training. Academic training as a pure scientist isn’t enough. Oftentimes, as a scientist, you may get analyses and results that lead you to make ‘horrible’ interpretations, and the documentalists or historians actually enable you to interpret these results, provide information on the treatment phases or tell you that a given decoration belongs to a different school.

Without this documentation, a scientific interpretation of the analyses is impossible or erroneous. This means re-educating the scientist and integrating them via a process that can be achieved with job experience or a Master’s, along with a learning process in a research team. One thing is for there to be different professionals with different kinds of training, and another is to work

5

collaboratively as a team. To achieve this, the restorer has to have scientific training and the scientist has to have humanistic training and training in restoration, and I think that this is not yet fully accomplished.

How have you seen the sciences applied to conservation of the cultural heritage evolve over these years?

At first it was quite disappointing. They hired you just to say they'd hired you, but you had no clout when the treatment was being carried out. There is a bit of this inertia left even today. Often the scientific study comes when the treatment is already underway. There is a problem with the poor timing between the analytical and treatment phases, as I have dramatically experienced.

Later, analyses were gradually introduced into the treatment process. I would visit the site with the architect, who more or less listened to you, although not all did; in fact, only a minority did. Very seldom did I manage to participate and see the results of my discussion. There are cases when I predicted that something would deteriorate, yet I was unable to stop it; over the years I found I was right. It’s sad because the heritage has aged or deteriorated. It’s an unfinished evolution, although things seem to be getting better.

What can be done to encourage all restoration and conservation projects to include analyses?

First, the site manager or architect or person in charge from the museum has to change their mindset. They have to realise that without scientific information, they could make major mistakes. Secondly, the scientists themselves have to learn how to participate and how useful this information can be. We scientists have to learn what we can humbly do within certain conservation processes, and here a dialogue is needed between the site management and its execution. Budgets also have to be made differently. There should be a time lapse between the preliminary studies and the treatment, as the analytical processes need time and have to be doable.

centrederestauracio.gencat.cat

In your opinion, what are the main problems with regard to conserving the historical heritage?

First, we have to accept that time is going to have its effects; we know that we cannot prevent deterioration from happening and that conservation is a battle that is hard to win. Secondly there is anthropic aggressiveness. In the era in which we live, conservation of the heritage is endangered because it is being damaged not only by the climate and pollution but also by use. All of this leads to wear and tear and prompts a complex debate on how the heritage can be conserved and made sustainable. There is no hiding from time, and oftentimes what has to be done, and it’s really hard to say this, is palliative treatments and attempts to slow down the process and make it more acceptable. In the past, people replaced things more readily. In treatments today, we try to conserve things, and products and treatments are applied that are not successful enough and in some cases even cause harm that didn’t use to be there.

We are at a very complex turning point in which we have to research and allocate economic resources and political will in this direction. There has been a commercial interest in selling products without fully knowing what their consequences may be. We have gone through a very counterproductive phase of commercial dissemination which has caused the opposite reaction: not doing any treatment. We have to find a balance, teach and learn from mistakes.

—

Observation by optical petrographic microscope in the laboratory at the school.

Photo: ESCRBCC

—

RESCAT

Index

6

Centre de Restauració de Béns Mobles de Catalunya

14

Diari Diumenge, 31 de maig de 2015

TARRAGONA |

PATRIMONIO | LA ARQUEOLOGÍA SOSTENÍA QUE SE CONSTRUYÓ EN LA ÉPOCA DE AUGUSTO Y NO SE EQUIVOCABA

La ciencia desvela la edad precisa del Pont del Diable Por primera vez se usan técnicas de laboratorio para certificar el año de construcción de este monumento de Tarraco JORDI CABRÉ

¿Cuándo se construyó el Pont del Diable? Hasta la fecha, todas las interpretaciones históricas y arqueológicas de este acueducto de 217 metros de longitud –que sortea el barranco de Els Arcs– apuntaban al mandato de Augusto (63 aC a 14 dC), el emperador que hizo de Tarraco la capital de su Imperio de facto.

Lo cierto es que las hipótesis estaban bien encaminadas. Por primera vez en un monumento de Tarraco, la datación tiene una aportación analítica de sus materiales gracias al trabajo minucioso de un equipo de investigadores de diferentes áreas (geólogos, biólogos, químicos y restauradores) pertenecientes al grupo interuniversitario GRAPAC-CETEC-Patrimoni (Grup de Recerca Aplicada al Patrimoni Cultural-Centre de Tecnologia per a la Conservació del Patrimoni) adscrito a la Universitat Autònoma de Barceclona (UAB) y al Institut Químic de Sarrià (IQS-URL). También ha contado con la ayuda del doctor Jorge Sanjurjo, de la Unidad de Geocronología del Instituto Universitario de Geología-Servicios Centrales de Investigación de la Universidad de A Coruña.

Muestras recogidas «Nuestro encargo por parte de la empresa responsable de la restauración, EMR ( Estudios y Métodos de Restauración), fue la de datar el monumento a partir de los materiales que lo configuran. Por ello, recogimos muestras de argamasa, básicamente morteros de cal. Unos estaban situados en la base de los pilares de los arcos, otros entre las juntas de los sillares y finalmente también se extrajeron muestras en la canalización, el specus», explica José Luis Prada, responsable científicotécnico de esta investigación.

La restauración del Pont del Diable «fue una gran oportunidad», explica la concejal de Patrimoni, Carme Crespo. «Nuestro objetivo es velar por el mantenimiento y la restauración del patrimonio y necesitamos por ello una investigación constan-

RESCAT

te para saber de dónde venimos y adónde vamos», añade la edil.

Las analíticas efectuadas en este material «señalaron que la construcción del acueducto sería hace unos 2.000 años, con un margen de error de un siglo», apunta Prada. Ello confirma las hipótesis que el acueducto de les Ferreres (otra de las denominaciones que tiene) podría haber sido ordenado durante el mandato de Augusto para suministrar agua del río Francolí a la parte baja de la ciudad, donde había las termas de Tarraco.

«Es la primera vez que un monumento de Tarraco puede datarse en base a los resultados de

Las pruebas indican que se construyó hace 2.000 años con un margen de error de cien años El acueducto se utilizó hasta el siglo IV porque se han detectado reformas de esa época los análisis de laboratorio de los materiales empleados en su construcción, en concreto por Radiocarbono (C14) y Luminiscencia Inducida (OSL)», explica Prada.

Técnica novedosa romana Una de las sorpresas agradables del periodo de investigación fue la técnica novedosa de construcción. «Los romanos construían generalmente con sillares de piedra sin mortero de junta, técnica denominada –al seco–, pero en esta construcción sí se utilizó este material para diversas funciones», explica Prada.

Por ejemplo: en la cimentación de base de algunos de los pilares encajados en la roca, entre los sillares para facilitar su colocación; para rellenar aquellas partes de la roca que pudiera quedar

afectadas a causa de un golpe o el trasporte, y se utilizó también en el specus que constituía la canalización del agua».

Cada uno de los morteros analizados, debido a su diferente uso y localización, tiene una composición diferente. Precisamente en los de cimentación de los pilares, el mortero es una mezcla más heterogénea, de aspecto granuloso y con presencia de tierras.

Este factor hizo más complejo aplicar los análisis para datación por Carbono 14 de la cal y por Luminiscencia (OSL) de los minerales.

«No obstante gracias al minucioso estudio de su composición mineral y de su granulometría se pudieron obtener resultados que han proporcionado una edad coherente con los obtenidos por los estudios arqueológicos sobre la edad del monumento», explica el geólogo.

El equipo de investigación interuniversitario GRAPAC-CETEC-Patrimoni (UAB-IQS) también encontró un tipo de mortero más ‘joven’ en el canal, correspondiente a la parte norte del acueducto, fechado en el siglo IV, «lo que indica que su uso para el trasvase de agua duró muchos siglos y que durante estas etapas necesitó reparaciones», concluye José Luis Prada.

Las piedras y su calidad Otra de las hipótesis que aporta este estudio científico es la posibilidad de que la construcción del acueducto, para sortear el barranco de Els Arcs, se hiciera simultáneamente en diferentes puntos y que el material utilizado tuviera diferentes canteras de procedencia.

«Hemos comprobado que la piedra no es uniforme en todo el Pont del Diable y que tiene diferente calidad o resistencia al deterioro, aunque todas sean rocas calcáreas», explica el científico.

La roca utilizada en la zona más cerca de la autopista, en la parte sur, es un material de mayor calidad y su estado de conservación, hoy en día, sigue siendo óptimo. «Es una roca extraída de la zona de Les Coves, de gran resistencia», explica Prada.

El acueducto romano que sortea el barranco de Els Arcs tiene una longitud de 217

Los investigadores de este proyecto.- Núria Guasch Ferré, licenciada en Geología; José Luis Prada Pérez, doctor en Geología y Marta Badia Cortada, licenciada en Geología. Los tres son investigadores de GRAPAC/CETEC-p (UAB/IQS(URL). FOTO: J.CABRÉ Por contra, la piedra calcárea que predomina en la vertiente norte, más cerca al barrio de Sant Salvador i Sant Ramon, es un material más heterogéneo, poroso y arenizable, extraída del Mas dels Arcs y zonas colindantes y «a simple vista ya se ve que su erosión es más significativa», añade el experto. Por ello, tanto los ar-

queólogos como el equipo de geólogos apuntan a que la construcción podría ser simultánea en diferentes grupos de trabajo y con el material más próximo a la construcción de pilares y arcos.

Las cavidades internas El mismo estudio geológico de los materiales originales y las

7

Diari Diumenge, 31 de maig de 2015

| TARRAGONA

15

PATRIMONIO | HAN TRABAJADO DURANTE CINCO AÑOS UN GRUPO DE INVESTIGADORES DE DIFERENTES ÁREAS

ANÀLISI PER JOAN

MENCHÓN Arqueòleg municipal

Les analítiques als monuments

ealitzar analítiques en els monuments no és una cosa nova. Ja fa una colla d’anys que en el Patrimoni de Tarragona s’està treballant d’aquesta manera. Als anys 50 del segle XX l’arqueòleg i químic José Sánchez Real analitzava reïnes de les àmfores trobades dins la Muralla. Als anys 80 i 90, les primeres ceràmiques romanes eren objecte d’estudis de termoluminiscència i difracció de raigs X. I no van tardar els estudis a la Muralla, la Catedral, la pedrera del Mèdol, la Torre dels Escipions i ara al Pont del Diable. La caracterització petrogràfica ha permès veure com a Tàrraco arribaven marbres de tota la Mediterrània, granits de Turquia o que la pedra d’Alcover s’exportava a diferents indrets de l’Imperi.

Intervenen geòlegs, biòlegs, químics, restauradors de béns culturals, enginyers, arquitectes, aparelladors, arqueòlegs i vells oficis com els picapedrers com especialistes en la talla de la pedra.

Els morters, la pedra, els pigments, les pàtines, les pintures... de murs, parets, capelles, pintures han estat objecte d’estudi i ens han deparat sorpreses i també interrogants. Les anàlisis ens diuen per exemple que cal conservar els líquens del Pont del Diable perquè protegeixen el monument. La salabró de la mar, els nitrats i fosfats malmeten la pedra, o un dels millors materials per la rehabilitació dels monuments és precisament el tradicional morter de calç.

Matèries orgàniques com l’oli o la clara d’ou s’usaven en patinar i impermeabilitzar la pedra; i fins i tot per endurir els carreus primer es submergien en aigua de calç.

En el cas del Pont del Diable s’ha anat més enllà de les pato-

R

metros para llevar agua del Francolí a la parte baja de la metropoli. FOTO: LLUÍS MILIÁN prospecciones geofísicas con georadar llevadas a cabo por la empresa SOT Prospecció Arqueològica –que se hicieron durante esta última fase de restauración del Pont del Diable–, han descubierto diferentes cavidades internas que hay en el monumento, originadas por las filtraciones de agua de lluvia y las procedentes del canal del Pont del Diable, monumento que forma parte de la lista del Patrimonio de la Humanidad de la UNESCO, desde el año 2000.

Garantías de futuro La restauración presentada en sociedad en septiembre de 2011 (con una inversión de más de 1,5 millones de euros) ya tuvo en cuenta la impermeabilización del specus para evitar que la lluvia y las filtraciones siguieran erosionando la piedra y aumentan-

do la fragilidad de este monumento.

«Las técnicas y los materiales de restauración utilizados durante esta última intervención se seleccionaron especialmente para que no fueran agresivos. Es decir para que no generaran nuevas sales que cristalizaran en el interior de los materiales, ni provocaran ataques químicos de tipo ácido. En definitiva que fueran compatibles física y químicamente con la naturaleza de las piedras originales.

Esta forma de actuación permite por tanto garantizar la estabilidad y frenar el deterioro del monumento. «Es importante que el criterio científico permita a partir de ahora en Tarraco que las restauraciones estén acorde con la identidad geológica de los materiales que configuran el monumento», concluye Prada.

Realitzant la cartografia gràfica dels morters. FOTO: GRAPAC-CETEC-PATRIMONI logies i tractaments. Amb revolucionaris mètodes de laboratori, tot indica que es va construir al segle I. Això fa pensar la seva possible relació amb la construcció de les termes portuàries;

❞

L’arqueòleg i químic José Sánchez analitzava reïnes d’àmfores de dins la Muralla als anys 50

o el seu funcionament fins l’Antiguitat Tardana gràcies a la datació del morter impermeable de l’specus.

S’obren preguntes i nous interrogants que el temps respon-

drà. El creuament d’aquestes dades amb l’estudi geològic, de l’estàtica del monument, de la tècnica constructiva donaran importants resultats. El cert és que en intervencions en el Patrimoni Històric com el cas del Pont del Diable, l’actuació interdisciplinar i la posta en comú de les estudis analítics proporciona uns fruits molt més interessants que treballar de forma aïllada.

La inversió pot semblar una despesa elevada, però certament és un percentatge petit en el volum d’una obra de restauració.

I per contra, els resultats ens proporcionen una informació essencial per conèixer la història del monument, com les seves patologies i en conseqüència els tractaments a aplicar.

—

Article from the Diari de Tarragona dated 31 May 2015 on the monumental restoration of the aqueduct of Tarragona.

—

centrederestauracio.gencat.cat

RESCAT

Index

8

Centre de Restauració de Béns Mobles de Catalunya

—

Study of mortars by selective staining in the laboratory at the school.

Photo: ESCRBCC

—

What projects in which you have participated would you highlight or did you enjoy the most?

LThe aqueduct of Tarragona, even though it was like passing a ‘kidney stone’. There were many disappointments, and the project was criticised in many regards, but I actually wish it were disseminated more. The work done was conservative, and some of them failed, while others tried to conserve something. I should say that when someone tries to conserve a piece of the monumental heritage, especially if it is outdoors, you have to consider another factor that wasn’t taken into account in the past, namely the entire ecosystem living within the monument, the lichen, the algae, the plants, the birds, etc. All of this is also part of a heritage that is within and with the monument. Making the natural heritage compatible and able to coexist with the architectural or archaeological heritage is a complex debate. Obviously, there is no need to reach extremes, but you do have to consider what should be conserved. One thing I found very drastic is eliminating the lichen from any type of building without considering whether this biological coating is important heritage in understanding the evolution of the climate or the Earth or knowing how the monument has been affected by pollution. I researched this a lot on the aqueduct of Tarragona and drew a very important lesson on this fraught dialogue between the architectural heritage, history and nature itself.

I would also highlight the spheres in Costa Rica, which gave me the amazing ability to see what the heritage mechanism was like around the world, and I realised that what is at the root of heritage conservation is actually people. The spheres were on the playground of a school, and the children themselves cleaned and maintained them. They were the pride of the children and the town hall. All of this enabled me to see that regardless of declarations of human heritage sites, if people are not engaged, conservation is impossible.

And getting back to teaching, what could be done to make science more involved in the world of conservation and restoration?

A good range of Master’s programmes is needed to help students educated in the sciences feel attracted to the field of heritage conservation. Government institutions themselves have to get involved in integrating scientists into this field. I think that this still needs to be done all over Europe.

And related to these times we are living in, how has the COVID-19 crisis affected teaching, or how might it affect it? What lessons can we draw from this experience?

There are two aspects that are diametrically opposed and cast doubt on different ways of seeing teaching. First, presence. It has been proven that remote teaching has some limitations. Students have a learning process. We aren’t machines; we’re human beings. We’re social animals,

RESCAT

9

—

Archaeology graduating class. 26 October 2006.

Photo: Joan Escudé

—

and we need direct communication. Plus, our ability to absorb language and knowledge varies widely. I don’t mean that everything has to be in person and nothing can be remote. A synthesis or kind of combination will likely be reached in which each teacher and school will find their own way of doing it. Obviously, there are some classes that can only be taught in person: workshops, laboratories, etc.

There are certain types of lessons or knowledge which have to be conveyed with this social connection. On the other hand, the new remote technological tools are very intriguing resources that offer a great deal of flexibility, especially among professionals, in terms of research and exchange. I think that the networks have yet to be explored.

With more experience, we’ll find out what works and what doesn’t, but presence should always have a place not only in the practical part but also when sharing information.

Do you have any curious stories you could share with us?

Hah! Plenty of them! From reactions for which you prepare an entire protocol and it never happens because something in the reactant was expired, to the polar opposite, such as the fact that many of my students have chosen to do research. That was an unexpected surprise. Some restorers wanted to learn more about science and have become researchers. It’s a generation that has gradually grown. Not so much in the first graduating classes, but after a certain 'critical base’ PhDs, PhD programmes and research began to emerge in Spain, Italy and France by students who had pursued Master’s degrees and then chose to devote themselves to research. This has been very gratifying, and I didn’t expect it.

Also related to this question, what are your takeaways after so many years of teaching?

Immense satisfaction. I've gone further than expected. It’s like you raise your voice, cry out, and suddenly you hear an echo. The fact that there are more and more generations... after twenty-some years; I've now taught hundreds of people who are in the field of restoration and even teaching. It’s highly gratifying as a teacher to see your

centrederestauracio.gencat.cat

lessons carried on. We could say that I have scientist and conservator children that have outdone their teacher.

Actually, a good teacher always wants their students to outdo them because it’s ultimately a kind of scientific parenthood; that is, it’s someone you’ve helped take a step who then goes further. This is also the human chain of science, and in this respect I’m deeply satisfied.

What will you miss the most after all these years?

What I’ll miss the most is the contact with the students and professors, which was wonderful. I’ll miss first the human contact and secondly climbing the scaffolding, touching the stone and running into former students at work. It’s been a wonderful period in my life. I hope that when the pandemic is past us I can resume contact with them. Teaching classes at the school with students who are motivated to learn has been a privilege. They really appreciate this teaching and love learning more.

I want to stress that it’s very important to do what you love. If you discover that you enjoy doing something, try to keep it because it’s a lifelong treasure. There’s nothing worse than doing a job you don’t like; it’s exhausting, even more so than people think. Having the privilege of doing what you love is totally worth it. We should reflect on that!

And now that you're retired, do you have any future plans?

I'd like to write. I have amassed lots of scientific information that I'd like to share in order to shed light on aspects of conservation that were done at a given time. My hobby is also writing literature. I would also like to write stories and novels, as I find this very satisfying.

Thank you so much, José Luis, for all these years of dedication to the field of heritage and training conservator-restorers, including myself. It’s been a real pleasure.

I’ve learned so much from you, and I know that everyone thinks so highly of you.

RESCAT

Index

10

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

MÒNICA BORRELL GIRÓ

The National Archaeological Museum of Tarragona (MNAT).

Tarraco within reach Presentation The heritage of Tarraco is usually connected to the upper part of the city of Tarragona and with the great monuments, such as the wall, the amphitheatre, the circus or the aqueduct. But Tarraco was a much richer reality. A bridge city for the Roman conquest of the Iberian Peninsula which had a huge impact on its immediate surroundings.

Probably for these reasons, the history of Tarraco has always been alive with more or less intensity. The medieval city was built, in part, on the dismantled Roman city, so we have evidence of it in the current walls and foundations of its buildings. This presence and monumentality of the heritage favoured that, in the 16th century, classical history came to the forefront. And although this memory has never been completely erased thanks to different personalities and circumstances over time, it has also suffered contempt, plunder, and speculation. Our own activity is sometimes the worst enemy of our memory.

Since the mid-19th century, the National Archaeological Museum of Tarragona (MNAT) has played a key role in this reality of the Roman heritage of Tarragona: by creating the leading collection in heritage preservation and management and in the knowledge of our history of 2,000 years ago as a more complex reality than the preservation of great monuments.

The long establishment of a museum The origins of the museum go back to 1835, at a time when the construction activity and especially the exploitation of what is known as the Port Quarry brought to light and allowed them to preserve treasures, such as the mosaic of the Fish, at the expense of destroying the layout of the Roman city.

The Museo Arqueológico Provincial was born in 1844 and grew debating, on the one hand, between the creation of private collections and, on the other, the constitution of the Provincial Monu-

RESCAT

—

Museum headquarters in the Town Hall building, located in Plaça de la Font. The chandelier and the mosaic of the Medusa can be seen in the foreground.

Photo: © Photographic Archive of the Centre Excursionista de Catalunya

—

Mònica Borrell Giró, director of the National Archaeological Museum of Tarragona (MNAT)

ment Commissions and the associated provincial museums.

It also had several locations until, in 1960, when Samuel Ventura was director, the museum opened at its definitive headquarters in Plaça del Rei, in a new building designed by Francesc Monravà, municipal architect of Tarragona, with a museum project supervised by Manuel Jorge Aragoneses.

We must not forget that in 1930 the Museum of the Roman-Christian Necropolis was opened, the result of scientific activity and the drive of Monsignor Serra i Vilaró.

With the creation of the state of the autonomies, the museum maintained state ownership and through the agreements of 1981 and 1982, management was transferred to the Government of Catalonia.

Over time, the museum took over the management of the archaeological heritage of the Government in Tarragona, as is the case, in 1995, of the transfer of the Roman theatre, the Els Munts and Centcelles sites, the Torre dels Escipions and the Arc de Berà.

Over the years there have been changes in affiliation —until becoming part of the Catalan Cultural Heritage Agency today—, but the MNAT was constituted and defined by its diversity of headquarters and heritage that includes: the Archaeological Museum, the Paleo-Christian Museum and Necropolis and the state-owned central services building; and the Roman Theatre of Tarragona, the Torre dels Escipions, the Roman Villa of Els Munts (Altafulla), the monumental

centrederestauracio.gencat.cat

11

—

The MNAT is currently made up of the Archaeological Museum, the Paleo-Christian Necropolis, the Tarraco Theatre, the Roman villa of Els Munts, the Roman villa of Centcelles (Constantí), the Arc de Berà and the Torre dels Escipions. Photo: ©MNAT Archive

—

ensemble of Centcelles (Constantí) and the Arc de Berà (Roda de Berà). A heritage declared a Cultural Object of National Interest (BCIN) that in 2000 was registered as a world heritage as part of the Archaeological Ensemble of Tarraco, at the same time as the walls, the circus, the aqueduct, the amphitheatre, the provincial and colonial forums, the imperial cult enclosure and the quarry of El Mèdol.

Moments of change Currently, the National Archaeological Museum of Tarragona is still undergoing intense changes driven by the headquarters refurbishment in Plaça de Rei. In April 2018, the Archaeological Museum closed to undertake a phase of architectural refurbishment by the Ministry of Culture and Sport, owner of the museum, and museographic refurbishment, by the Government of Catalonia. Currently, a summary exhibition Tarraco/MNAT can be seen at Tinglado 4 in the Port of Tarragona, the museum’s temporary headquarters during the works.

Although these investments are the starting point of a new era, they are based on a reflection

RESCAT

Index

12

Centre de Restauració de Béns Mobles de Catalunya

and a review of the museological programme as a whole, which aims to put the museum at the service of the citizens, visitors and tourists, so that they can glean the meaning and legacy of this past, which is one of the roots of current society. And this process starts from a solid foundation, the museum’s collections and the heritage scattered throughout the area of Tarraco.

One of the strong points and a distinctive element of the MNAT is its collection, a reflection of the Roman Tarraco, capital of the province of Hispania Citerior. An iconic and oft-cited collection, which allows, together with all the MNAT headquarters, to build a global discourse on Tarraco and its territory from the 3rd century BC to the 8th century.

The new exhibition will illustrate a journey through time across ten centuries, discovering a Roman capital, from its origins to its archaeological rediscovery. If we became time travellers, we could tour the exceptional public spaces of the city, capture the reflection of the power of Rome, and delve into the areas of daily life of its diverse inhabitants, the value and richness of its territory, the most extensive province of the Empire, with examples of the richest villas of the Tarraco elites.

The new exhibition aims to witness the impact, evolution, complexity and heritage of Roman culture in Tarragona, a significant and relevant space for our diverse public.

From collection to territory At the same time, the new exhibition aims to maintain the dialogue with the rest of the world heritage, especially with the headquarters of the MNAT itself, in Tarragona and the region.

In Tarragona, work is currently being performed at the Tarraco theatre. The theatre, along with the circus and amphitheatre, was one of the spectacular buildings that a city modelled on Rome was supposed to have. The theatre was the first to be built, between the local forum and the port, one of the most lively and dynamic areas of the city.

The history of this space has been very irregular, but recently it has been the subject of restoration work with the recreation of the cavea as its most unique element. The aim, however, is to restore its connection with the urban environment and approach it, not only because of its monumental uniqueness, but also because it explains one of the most dynamic areas of the city: the port and its port district.

A very different evolution is that of the Paleo-Christian necropolis. While at the turn of

RESCAT

—

Tarraco/MNAT exhibition, at the temporary headquarters of the MNAT in Tinglado 4. Photo: © Emma Jové (MNAT)

—

the 20th century Monsignor Serra i Vilaró brought to light one of the most extensive Roman-Christian necropolises known by providing interesting information and an exceptional epigraphic collection, the recent urbanization of adjacent sectors, such as the PERI, allowed areas of this city to be recovered and thus sew the monumental Tarraco within the walls with extensive and dynamic suburbs —where this extensive Christian necropolis ended up being built—, the port area and the roads that connected people, ideas and goods to the Peninsula inland. The Necropolis is therefore part of the overall story of Roman Tarraco.

In this context, and located on the road that led to the south of the Peninsula and inland, next to the Tulcis, the current Francolí, a unique testimony of late antiquity is preserved. Centcelles is known for the extraordinary mosaic that deco-

13

rates the central room, and although questions posed by specialists remain unanswered, we are faced with a testimony of the occupation and exploitation of the ager in Tarraco.

And if we place this unique heritage to the south, to the north of Tarragona we have another element that reminds us again of the location of the funerary areas on the entrance roads to the city. It is known as the Torre del Escipions, a funerary monument built at the foot of the Via Augusta, a road that had an emblematic landmark, today known as the Arc de Berà.

It is in this area to the north where we also find the villa of Els Munts. It would have been an area of intense activity, including agriculture, extraction of stone resources, maritime and road traffic. Also a privileged environment where an agricultural villa is transformed into a sumptuous villa, probably connected to imperial power.

centrederestauracio.gencat.cat

As you will see in this publication, the villa stands out for its exceptionally preserved —mosaic, pictorial and archaeological— remains and for years we have been working comprehensively on its study and dissemination and on a preventive conservation plan promoted by the Centre for the Restoration of Artefacts of Catalonia.

At this time, the MNAT is focused on an update and summary of the archaeological research carried out at the Els Munts site to make key information for the study of Romanity available to the scientific community and, at the same time, lay the foundations for a future project.

This research update is both crucial for dissemination, the restoration of routes and presentation and mediation elements, as well as for the educational project, currently under review and rethinking for the whole museum, and which will be implemented in Els Munts.

RESCAT

Index

14

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

JOSEP ANTON REMOLÀ VALLVERDÚ

The Roman villa of Els Munts: The historical and archaeological context

THE ROMAN VILLAGE OF ELS MUNTS, LOCATED AROUND 12 KM NORTHEAST OF TARRACO, IS THE RESULT OF A COMPLEX SUCCESSION OF BUILDINGS Introduction The Roman villa of Els Munts, located around 12 km northeast of Tarraco, is the outcome of a complex succession of buildings generated over more than seven centuries of steady and virtually uninterrupted occupation. In the almost 200 years of the existence of the early imperial villa of Els Munts, its period of peak splendour and architectural development, the buildings underwent a series of transformations which, together with the constructions of earlier and later buildings, comprise an architectural reality that is complex to interpret and articulate. This complexity, already sensed in the earliest excavation campaigns, was confirmed in later archaeological interventions, which are the foundation of the first proposed hypothesis on the architectural evolution of the villas which succeeded one another in the Roman and late ancient world.

After it was abandoned at some uncertain point in the 7th century, much of the remains were disassembled primarily by humans, but also by weather. This continued until the 1960S, when the Provincial Archaeology Museum under the stewardship of PM Berges (1970, 1977) started an extensive excavation programme which partly affected the upper platform and the garden and almost entirely encompassed the triclinium and adjacent areas, the “Castel” reservoir, the southern baths and what are known as the “beach baths”. The main documentary source available comes from the excavations undertaken by the National Archaeology Museum of Tarragona (MNAT) under the direction of F Tarrats between 1995 and 2007 (Tarrats et al. 1998, 2000, 2008; Tarrats/Remolà 2007).

RESCAT

—

Schematic layout of the Roman villa of Els Munts. Photo: ©MNAT Archive

—

Josep Anton Remolà Vallverdú, conservator and head of the Collections and Research Area at the National Archaeology Museum of Tarragona (MNAT)

— The villa in the era of Augustus (1st century AD) Although we are aware of the existence of a phase from the 1st century AD based on the study of Italic terra segillata, south Gallic terra segillata and Hispanic terra segillata (Tarrats 2003), the first structural proof came in 2004 on the far eastern part of the walkway in the semi-underground floor, beneath the preparation level for the mosaic. The structures documented, which were torn down to build the village in the 2nd century AD, correspond to a press which now joins the one identified early in the southeast in the excavations from the late 1960S. Based on the description of the building technique, a preliminary analysis of the visible structures enables us to cautiously identify structures that might be associated with this building, extending southward to the location of the villa’s later southern baths from the 2nd century AD. Structures from prior to the construction in the 2nd century AD can also be found on the upper platform. Also to the north, structures from the 1st century AD which may also be associated with this building have been documented, albeit without any clear stratigraphic evidence.

centrederestauracio.gencat.cat

The villa in the era of Hadrian (1st century AD) Between the late 1st and the early 2nd centuries AD, the earlier villa was torn down to prepare the land for a new, larger and more complex building comprised of a hierarchised succession of constructions which urbanised much of the southern slope of Els Munts. The project, whose axes run northeast / southwest, shows a layout similar to what is found in the urban nucleus of Tarraco and the preceding villa. The ensemble had to be designed in terraces which regularised the slope extending from Altafulla beach to the upper flatland.

The construction project of this villa was a complex process: we have posited the existence of an initial project which underwent major changes during its execution that considerably expanded the size and monumentality designed in the original project.

We shall concentrate on the second phase, which is the project that was ultimately executed, and the source of most of the conserved remains.

During the execution, or at least before construction was finished, the project underwent a profound change. The built structure was given no decorative treatment on either the walls (panelling or murals) or the floor.

Aerial view of the Roman villa of Els Munts.

Photo: ©MNAT Archive

—

RESCAT

15

Index

16

Centre de Restauració de Béns Mobles de Catalunya

—

Close-up of the walkway paved with mosaic that articulated the semiunderground floor of the main building in the villa. Photo: ©MNAT Archive

—

RESCAT

The changes affected the ensemble as a whole, which was extended northward as far as the northeast slope of the upper flatland and southward up to the beachline. The most notable change documented in the main building is the replacement of the porch connecting with the southern baths with a crypto-porch with an attached hallway and rooms. This was a semiunderground room which increased the inhabitable area but hindered the initial plans to situate the cisterns which were to supply water to the bath building under construction at this point. The water supply system had to be totally overhauled.

Hypothetically, the new water infrastructures must have been built with this change in the project, such as the ones documented on the upper flatland (“Tartana”), which may be associated with the water supply of the building’s main floor, or on the northwest slope, called the “Castel” reservoir. The large cistern/nymphaeum located in the garden between the main building and the southern baths, which was meant to supply the latter with water, may also be related to the construction of this crypto-porch.

The main floor of the main building opened to a porticoed gallery with views of the garden and the sea. A series of important rooms were reached via the gallery and might hypothetically be the source of the mural fragments representing agonistic

crowns with tituli picti in Greek inserted into an architectural scene. The paintings in opus vermiculatum representing the Muses and a male portrait most likely come from the gallery.

Likewise, an extensive set of statuary, including one clearly portraying Antinoös, the lover deified

by Hadrian, also come from the main floor.

The best conserved remains come from the semi-underground floor of the main building, which was connected to the upper floor via staircases which connected to a covered walkway decorated with geometric mosaic on the floor and a mural on the walls. The walkway led to a series of rooms (primarily the cubicula with an antechamber and chamber) decorated with murals.

One of the rooms in the semi-underground floor was transformed into a cistern on the orders of Avitus and Faustina, an act commemorated by a inscription painted on a depiction of the god Oceanos. This Avitus is unquestionably Caius Valerius Avitus, as documented by the discovery of his personal seal in a well on the upper floor.

Via the epigraphy, we know that he was transferred from his native Augustobriga (Muro de Ágreda) to Tarraco, where he was designated duumvir on orders of the emperor Antoninus Pius in the mid-2nd century AD. At the other end of this walkway, another staircase connected to another perpendicular

17

walkway leading to a large triclinium decorated with exceptional mosaics and seven small fountains in the main room. The crypto-porch connected with a portico which ran straight as far as the building housing the southern baths.

Another stretch of the perpendicular walkway led to the Mithraeum, one of the most exceptional and enigmatic buildings in the ensemble.

The Mithraeum stands out for its large size, similar to that of the Mithraeum delle Terme di Caracalla (Rome), as well as for its rural location.

This mysterious religion from the East tended to have small local groups of followers, primarily in military encampments and cities. The sanctuary was comprised of a pronaos, a grotto or cave and a worship room. The purpose of the pronaos is not clear. It may have been a meeting room for followers, a dressing room (apparatorium) and place to prepare the paraphernalia for the ceremony, or a kitchen to prepare ritual meals.

The ritual banquet in which the god celebrated the end of his mission on Earth before getting into his cart and embarking upon his voyage to heaven was held inside the cave or speleum.

The celebration consisted in a meal in which the seven grades of initiates (Corax, raven; Nymphus, bridegroom; Miles, soldier; Leo lion; Perses, Persian; Heliodromus, sun-runner; and Pater, father) acted according to their assigned roles. The initiates in the first three grades acted more as servants than as true participants in the mysteries. At the back of the cave, the three-part

centrederestauracio.gencat.cat

—

Overview of the building housing the southern baths. Photo: ©MNAT Archive

—

—

The southern baths from the entrance atrium. Photo: ©MNAT Archive

—

RESCAT

Index

18

Centre de Restauració de Béns Mobles de Catalunya

—

Pool/ nymphaeum in the frigidarium of the southern baths. Photo: ©MNAT Archive

—

RESCAT

worship room was raised on a podium, which must have harboured the depiction of the tauroctony, the culmination of Mithraic doctrine.

Slight fragments of the exuberant iconography which characterised Mithraic sanctuaries was recovered, both in the floors and cladding and on the furnishings. What clearly stands out is a fragment from a sculptural group of marble from Luni/Carrara representing two figures, one almost life-sized and the other smaller, both covered with cloaks.

The building housing the southern baths was reached via a walkway which led to the atrium.

The atrium, in turn, led to a large dome-covered luxuriously decorated room. The thermal ritual began in this room and included different rooms with warm and cool pools. Most prominent is the natatio and the pool/nymphaeum of the frigidarium. Next to the natatio, a walkway decorated with paintings depicting a garden led to the latrines, located next to the furnaces that heated the water and air.

Proof of the magnificent decoration of this building comes from the scant signs of mosaics, the remnants of marble cladding and the sculptural group recovered, which included statutes of Asclepas, Hygieia and Eros, a possible depiction of the goddess Fortuna and a scutum profusely decorated with iconography with cosmological meaning with the remains of the forearm of a male figure. Most of them can be dated from the

2nd century, between Hadrian and the Antonines.

From one end of the southern baths it was possible to continue the route to what were known as the “beach baths”, a monumentalised fountain with a freshwater pool on the beach.

North of the villa was a large quarry which probably reached its peak extraction during this period. To the west was an extensive burial ground in use between the 3rd and 7th centuries AD. The start of the necropolis seems to dovetail with a critical episode which put an end to the late imperial villa. The villa was attacked in around the third quarter of the 3rd century, as proven by the discovery in the semi-underground floor of a corpse with marks from a cutting object on the cranium and signs of a fire that affected the main building, although it did not collapse. The remains, which are partly calcinated, correspond to an adult individual (30-40 years) carrying a case with 15 sestertii and one Dressel 20-type lamp in the right hand.

We can conjecture with some conviction a possible relationship with the general situation in Tàrraco and the western half of the empire in the late 3rd century. In the time of Gallienus (ca. 260), Frankish contingents crossed the Pyrenees and reached as far as Tarraco, where one part captured ships anchored in the city’s port to head to North Africa, while another part remained in the territory for a 12-year period (Eutropius, Aurelius Victor, Eusebius-Hieron and Orosius).

19

The late Roman villa ( 5th century AD) Throughout the 4th century, the villa remained active yet underwent profound quantitative and qualitative changes. Hypothetically, the deterioration of the main building may have shifted the residential function to the bath building. In this period, the necropolis started late in the preceding century continued to develop.

There are signs of new building activity in the early 5th century, specifically the restoration of the portico of the gallery on the main floor (and adjacent rooms? which had been damaged in the incidents in the late 3rd century. A significant part of the architectural and decorative elements recovered in the demolition levels conserved in the semi-underground floor seem to come from this period: capitals, column shafts, capitals from the lessene, etc. At an imprecise date, this part of the building collapsed, but the late Roman villa carried on until the late ancient period.

Bibliography

—

The southern baths from the walkway leading to the latrines.

Photo: ©MNAT Archive

—

P.M. Berges (1970), “Informe sobre ‘Els Munts”, Boletín Arqueológico, IV, 105-112, Tarragona, 140-150.

P.M. Berges (1977), “Nuevo informe sobre els Munts”, Estudis Altafullencs 1, Altafulla, 27-47.

F. Tarrats (2003), “La terra sigillata i les primeres fases d’ocupació de la vil·la romana dels Munts (Altafulla, Tarragonès)”, Revista d’Arqueologia de Ponent 13, 315-335.

F. Tarrats, J.M. Macías, E. Ramón, J.A. Remolà (1998), “Excavacions a l’àrea residencial de la vil·la romana dels Munts (Altafulla, Tarragonès)”, Empúries, 51, 197-225.

F. Tarrats, J.M. Macias, E. Ramón i J.A. Remolà (2000), “Nuevas excavaciones en el área residencial de la villa romana de ‘Els Munts’ (Altafulla, Ager Tarraconensis), estudio preliminar”, MM 41, 358-379, Tafel 64-67.

F. Tarrats, J.A. Remolà (2007), “La vil·la romana dels Munts (Altafulla, Tarragonès), J. A. Remolà (coord.), El territori de Tarraco, vil·les romanes del Camp de Tarragona, Forum 13, Tarragona, 95-117.

F. Tarrats, J.A. Remolà, J. Sánchez (2008), “La vil·la romana dels Munts (Altafulla, Tarragonès) i Tarraco”, Tribuna d’Arqueologia 2006, 15, 213-228.

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: site | MATERIAL / TECHNIQUE: diverse DATE/ERA: Roman, from the 1st century BC to the 7th century AD | LOCATION: National Archaeology Museum of Tarragona (MNAT) Roman villa of Els Munts, Altafulla (Tarragonès) | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

20

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

PERE ROVIRA

Conservation-restoration interventions at the Els Munts site

I VAGUELY REMEMBER THE FIRST TIME I CAME TO ELS MUNTS, TOWARDS THE END OF 1998, with Josep M. Xarrié and Eduard Porta In the mid-1990s, under the direction of Francesc Tarrats, excavations had resumed in the Roman villa of Els Munts, and the Restoration Centre paid a visit to see and assess the state of conservation of the mural paintings that had emerged during the excavation in the ambulatio rooms. At the entrance of the enclosure, at the time, on the hortus side, there were two caretakers dressed as officials, sitting on two beach chairs, at the foot of a carob tree, guarding the site, which was very unprotected then.

It was not a coincidence or an administrative extravagance, but a reality that proved the importance of the site, and of what had been found there since the last excavations in the 1970s. Everywhere in the villa exuded luxury and comfort. Remains of the stones that had adorned it, from all corners of the Roman Empire, appeared everywhere and testified to the category and importance of this archaeological site. A reality that at the time did not seem like it, but that has become extremely obvious as it has been excavated and restored.

During that first visit, we focused on the domus area to see the new mural paintings discovered in the cryptoportico area and its large mosaic. One of the guidelines that someone had given the archaeologists was that as soon as they discovered the mural paintings, to protect them with a gauze attached with Paraloid® B-72 resin, at that time the “manna” that saved and conserved the heritage. The recommendation was not bad, and in the eyes of a restorer it obeyed a specific temporary fastening criterion, to avoid risk of detachment.

But this misunderstood detail led to protection being applied to the whole pictorial ensemble, regardless of the area, and turned the whole ensemble into a kind of wrapped present. Despite

RESCAT

this, the real problem was that these fabrics glued with resin spent too many years on the frescoes, apart from the fact that they were placed without properly cleaning dirt from the surface of the murals.

What was supposed to be a temporary protection was prolonged in time, and created an added problem to the alteration itself of the outdoor frescoes. The mixture of acrylic resin with solid remains deposited on the surface forms a kind of hard and resistant film, difficult to remove as the resin becomes insoluble, and at the same time does not allow the painted walls to breathe naturally.

So, one of the first immediate actions to be taken should have been to remove the fabrics (some of which were already beginning to come off) and especially the resin, which conditioned the stability and aesthetics of the fresco. Its removal, years later, did not lead to the total elimination of Paraloid®, since due to its strong adhesion it still remained all over the surface.

—

Partial view of the gallery and the lower rooms of the domus, under the roof

—

Pere Rovira, curator-restorer, coordinator of the Mural Painting, Stone Sculpture and Sites Area

All this, in the long run, has meant that some parts are petrified and lifting, due to the barrier effect that the interior-exterior moisture transmission has combined with the presence of salts.

This issue entailed restoration on several occasions, to prevent them from further degrading.

Nevertheless, the salts contained in the walls have inevitably continued to come out. One of the most recent studies we have carried out at the CRBMC has been to assess the behaviour of the salts and their removal, as well as the cleaning of resin residues using the Wolbers gel methodology, a topic already covered in another article.

One of the first actions for the conservation of the site, and probably the most important since excavations were resumed, was placing a temporary roof over the area of the domus, which largely protected its remains. This large preventive action, the first on an open site in Catalonia, kept the highest and most voluminous facings ever found in a site in our country protected from rain damage, and at the same time allowed us to preserve the original walls, mosaic and mural paintings. Obviously, this prevented the uprooting of mosaics and mural paintings, actions that were all too common in past archaeological campaigns.

But what was good temporary protection, in the long run also ended up being a problem,

centrederestauracio.gencat.cat

—

Part of the mosaics extracted from the ambulacrum and deposited in the storerooms of the MNAT

—

21

derived from this same temporary situation. The asbestos material which the roof is made of must be removed, by law, although it has occasionally been replaced due to the alterations it has suffered.

The next biggest problem that appeared was that the rain collected by the roof decanted too much water on the side of the cryptoportico, since there were no gutters that carried water away from the rooms, which caused a lot of moisture and salts to emerge, agents which have damaged the mosaic and murals in that area.

In fact, the protective perimeter of the roof is at the edge (without borders) of the domus elements that it aims to preserve, whereas other parts of it are totally outside, like the peristyle and the triclinium, from which mosaics were taken and transferred, which are waiting in the depository to one day return to their rightful place.

The roof’s intention at the time was to protect those more archaeologically important and better preserved parts of the domus, perhaps in the hope of extending the coverage at a later stage. But the years went by and it was not extended. The metal support structure has also aged. Although it is stable, it has gotten rusty.

And the multiple cement support bases included within the original walls have also damaged the original walls they are supported on, basically

RESCAT

Index

22

Centre de Restauració de Béns Mobles de Catalunya

—

Overview of the roof that covers an important part of the domus

—

—

The support areas of the old roof structure have also conditioned the conservation of the place it occupies, which will not happen with the new roof, as the supports will be far away from the house

—

because they were made of mud. Leaks from the wear and tear have also appeared and need to be repaired quickly to avoid puddles of water and the subsequent alterations they entail.

The complex hydrological system that the whole villa presents makes the conserving its elements more difficult, although the slope where it is located faces the sea. When the villa was active, water movements were probably controlled and properly directed, which meant that there were no logical problems of a corroded site.

In fact, many of the original pipes and drains of the domus could continue to operate if their course was not blocked by occlusions and earthworks, which would facilitate this necessary drainage. The very constructive morphology of the domus, integrated into the hill and taking

RESCAT

advantage of its slope, causes the water from the upper area to filter inwards and make a logical descent, a problem that the temporary roof cannot solve by itself. In this way, the appearance of sources of water on days of heavy rain ends up also leading to the site’s deterioration, which is very common in archaeological sites.

Given the problems caused by water at the site (water movement and drainage), one of the main objectives of the National Archaeological Museum of Tarragona (MNAT) was to plan to cover the entire site with a new roof. The new project was developed by the office of architect Estanislau Roca (RC Arquitectura i Projecte Urbà, SCP), and was done at a conservation level following the guidelines given by the CRBMC, in order to completely preserve the elements contained in the site.

23

The initial project was really spectacular, and allowed to visit the entire site along a high walkway, while protecting the whole area. The initial idea was also for the roof to be modular and that it could be consecutively extended over each area, until the whole site was covered. This would have made it possible to diversify the cost of the whole ensemble and distribute it over several years, depending on the possibilities. But we were faced with the economic reality of the Department of Culture, so we had to change the initial intention of the MNAT and the CRBMC to cover the entire site, and only partially cover the area of the domus. This major action is planned for the near future, and will replace the temporary roof with a new larger (but not full) roof, with wide enough margins to better protect, at least, the paintings and the mosaic. This roof will also reinforce the structures outside the scope of the domus and channel the water collected by the roof, which will be directed mainly towards the original drains already present at the domus. The new project, despite being more modest and without modulations, is still a good project, in order to protect the remains.

However, despite the Museum’s huge efforts, so far only the water from the old roof has been channelled, already helping to improve general conservation. This harsh reality contrasts with the rest of Spain and other countries that cover many of their sites, at least the most important ones.

Something we were pioneers at and are now the last in line. The Department of Culture prefers to invest the little money it has for archaeological sites in building fake walls and theatrical decorations, for the enjoyment and entertainment of tourists accustomed to Netflix series, rather than carry out serious site preservation projects. Mental recreations will not make us knowledgeable in the eyes of science and history; nor richer. Of course, tourists will have the ideal theme park to be satisfied with their visit. For now, we are forced to put another “plaster” over the site’s suffering: a partial roof over the domus of the most important residential villa in the Iberian Peninsula. This is better than nothing. But it’s half a job.

At all sites, the maintenance and conservation-restoration costs, with the continuous and irreparable loss and damage to elements, and with most mosaics and mural paintings forgotten in the depositories because they can not return to their place, far exceed the cost involved in building a roof. Never put off until tomorrow what you can do today. Dum Roma deliberat, Saguntum perit.

centrederestauracio.gencat.cat

— The latest studies commissioned in 2020 by the MNAT to Flumen, SL for the improvement of the site’s surface drainage give a very clear diagnosis of the hydrological and hydraulic behaviour, both of run-offs and sediment transport and deposition, as well as action proposals to reduce the effect of flooding and subsequent erosion. Despite knowing the reality around us, the best recommendation pointed out by the study for the preservation of the site is its complete coverage. Fancy that! It also says temporary covers can be chosen for areas that do not have natural drainage, such as the area of the domus, the Mithraeum, the deposit of the hortus and some rooms in the southern baths. It also points out the need to build small moats and slope changes, in order to channel surface water safely and prevent it from depositing on visible elements. Carrying out these actions will be essential for the conservation of the site, and thus also start conservation-restoration actions with long-term stability guarantees.

Map of the areas most at risk of alteration.

Illustration: CRBMC

—

RESCAT

Index

24

Centre de Restauració de Béns Mobles de Catalunya

Going back to this article’s opening line, one of the important things we also saw that day was the fresco decorative mural, which presided over the fountain that was located in one of the rooms facing the ambulatio. The construction of a cistern and a fountain was an important enough action for it to be erected in honour of the god Oceanus, and to include the names of the factorum of this construction: Caius Valerius Avitus and Faustina, the lords of the house.

The discovery of such an exceptional document conditioned a series of assessments on its preservation, and it was decided that it would be best to tear the front down and move it inside, a decision we probably wound not make today. The intervention involved detaching this mural, the first major action by the CRBMC on-site. That detachment was very laborious, as it was done vertically, and took advantage of the section of the wall above. The CRBMC transported the

RESCAT

detached mural to a stationary movable support, so that it could be seen inside the Els Munts Interpretation Centre.

In the area of the domus cryptoportico, the intervention on the long tile mosaic, which is the only one in the villa that is still in its original place, is particularly noteworthy. This spectacular mosaic underwent cleaning and consolidation, so that it does not degrade further, especially regarding points lifting with tile loss, areas where water collects (derived from rainwater penetrating inside the residential area) and clay tiles that were disintegrating. The restorations were carried out over several years by various specialized professionals, under the supervision of the CRBMC. Currently, despite the needs, no new maintenance actions will be performed until the new roof is installed. Unfortunately, the rest of the mosaics in the villa were torn down and placed on small panels supported with cement,

25

—

Design of what the new roof in the first project would have been, but which could not be carried out due to lack of financial resources.

Design: RC Arquitectura i Projecte Urbà, SCP

—

—

The quality of the mural paintings that adorned the rooms is difficult to preserve given the presence of moisture

—

centrederestauracio.gencat.cat

as was traditionally done, stored in the depository. The intention is that one day, when there is cover, they can be returned to their original spaces, in order to give them meaning and, above all, the visibility that they currently lack.

CRBMC’s line of action on the site began with the Oceanus mural painting and the cryptoportico mosaic, followed by various mural painting restorations, focusing mainly on the residential house and the entrance gallery to the baths (ambulatio). All these actions have served to preserve these pictorial remains, essential to see the site’s decoration.

As we will be see in the various articles in this monograph, the interventions always end up colliding with the humidity problems and environmental conditions, and especially with salts naturally present in the site. The importance of consolidating all the facings with mural paintings over the years is particularly noteworthy.

The last interventions have focused on studying the alterations suffered by the mural paintings of the domus, while maintenance work has been done, with the removal of the new emerging soluble salts and microbiota, and to continue consolidating the affected mortars and paintings. A job that has had particular incidence this past year, due to the amount of rain that has fallen.

One of the most spectacular finds made during the excavations in the domus has been

RESCAT

Index

26

Centre de Restauració de Béns Mobles de Catalunya

—

—

Topographic map of the observed run-offs (red arrows) and main incidence points (numbered triangles). (Flumen, SL. Source: ICAC)

Mural painting of Oceanus, after restoration

—

—

—

Location of the cistern and the fountain where Oceanus was located, which the hosts of the house had buvilt. Photo: Pere Rovira

— RESCAT

27

the coffered ceiling with fresco polychrome, which was located in one of the secondary rooms (no. 4700), a piece that, due to its characteristics, is unique in the empire at this time. Its multiple fragments were recovered, and its recomposition began in 2006. We are currently working on it, so that by 2022 it can be exhibited fully restored. An artistic marvel of great technical complexity in terms of its restoration.

The southern baths represent a very important part of the site, with many preserved spaces, where work has also been done to consolidate the remains of mural paintings and mortars in the pools and accesses, as well as to partially recover the demolished parts of the hot water pool floor (caldarium). As in the other rooms and spaces of the site, only part of it has been done, and it is necessary to continue working on its restoration and maintenance.

Recently, efforts have also focused on the Mithraeum, the worship space of the villa, of a quality comparable to that of the baths of Caracal·la, in Rome. It is a very important and quite damaged room, which is not currently included in the tour, as it is still under restoration. This area, built as an adjoining wing, perpendicular to the ambulatio, requires continu-

centrederestauracio.gencat.cat

ous interventions to consolidate the mortars and restore the mural paintings on the preserved facings. Also, as in other areas on-site, the perimeter land needs consolidating and adequate draining so that the water does not damage it further.

As in the whole site, after an excavation, the emergence of new built structures causes their continuous wear, as they have been stripped of protection. It is essential to arrange rainwater movement, in order to prevent landslides, especially severe in the Mithraeum. And they are the necessary preliminary steps before the final restoration of mortars and mural paintings. For the time being, the areas with mortars and mural paintings have been temporarily consolidated, awaiting a global restoration of all this space, which must include the relocation of ashlars and fallen elements, and the preparation of available ground, if that is possible.

Other unique site elements, such as tanks and cisterns, have also been the subject of intervention, in this case the large rectangular cistern called “Castel” and the tank called “La Tartana”.

The cisterns have been essential elements for the life of the villa and its crops, and its conservation helps explain this, as well as showing the

—

The gallery mosaic after the restoration treatment

—

RESCAT

Index

28

Centre de Restauració de Béns Mobles de Catalunya

—

Beginning of the assembly of the ceiling fragments recovered in the excavation of room no. 4700. Photo: Misi Bruned

—

— Romans’ excellent construction skills. Cistern restoration focuses mainly on replacing the joint mortars and consolidating the slabs of lime mortar that covered their walls, apart from removing the upper plants and carrying out the necessary biocidal treatments so that they do not degrade.

The architectural actions within the museographic field that have been made in the visitor’s tour have always had two very clear aims. On the one hand, to mark a more or less safe line of passage, with firm enough ground suitable for walking, in order to avoid margin exits that could damage the excavations and the visitors themselves. On the other hand, to point out the different areas and give a tidy overview of the site and all its spaces.

It is important that these actions do not damage the original elements or structures, nor that they condition the archaeological aesthetics, which is why we have worked together with the architect and the archaeologist. The inclusion of new elements such as wooden parterres and protective railings help to preserve the ensemble and facilitate the passage of visitors.

In fact, it is important to ensure that the new elements brought to the site aid its conservation, especially adapting accesses that must facilitate the circulation of rainwater. The last action of this type, a project drafted by the architect Miquel Orellana, focused mainly on the area of the deambulatio and the baths. Despite some liberties taken when reintegrating some architectural elements, the route through the site is logical and understandable, and includes almost the entire uncovered space.

The site’s greatest enemy are all those degrading agents of biological origin that coexist within it, so it is necessary to apply good preventive conservation, which can never be left out. As a whole, one of the main objectives for the site’s maintenance (like that of all outdoor archaeo-

RESCAT

Appearance of the cold water pool (frigidarium), outdoors, before the intervention

—

logical sites) is to have a good annual preventive and maintenance programme, to minimize the impact of vegetation and microbiota on all uncovered structures and elements. Although minimizing biological elements in an outdoor environment is a pipe-dream, it is necessary to be insistent and constant when treating biota, and to keep it from exceeding the point in which its proliferation can condition the conservation of the ensemble, always respecting the environment.

The interventions described in this monograph are a short summary of what has been done and what must be done in the coming years. No matter how much is done, a site of these characteristics will always have pending actions, but we want the ones we perform to not condition the future. Carpent tua poma nepotes.

—

General appearance of the Mithraeum before the intervention

—

29

—

Hot water pool (caldarium) with a partial reconstruction of the heating system

— —

The walking area in the direction of the baths, with the new pavement that facilitates access

—

—

Large cistern, called “Castel”, with biological colonization derived from its location outdoors.

Photo: Sílvia Llobet

— —

Increase in higher plants in the Mithraeum area.

Biota growth control requires continuous maintenance of the site. Photo: Sílvia Llobet

—

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: site | MATERIAL/TECHNIQUE: mural painting | DATE/ERA: Roman, from the 1st century BC to the 7th century AD | LOCATION: National Archaeology Museum of Tarragona. Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 14145 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

30

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

M. JOSÉ GRACIA TARRAGONA

Preventive conservation plan of the Roman Villa of Els Munts

BEFORE DISCUSSING THE PREVENTIVE CONSERVATION PLAN, I BELIEVE IT IS ESSENTIAL TO RECALL THE DEFINITION OF THE BASIC TERMS ON WHICH OUR JOB IS BASED. THESE ARE TERMS WE USE EVERY DAY, AND IT IS IMPORTANT TO BEAR THEM IN MIND. The UNE-EN 15898 standard, dated March 2012, defines conservation as “measures and actions that seek to safeguard the cultural heritage while respecting its heritage significance, including its accessibility to present and future generations.

Conservation encompasses preventive conservation, remedial conservation and restoration.”  Preventive conservation is defined in this standard as “measures and actions that seek to prevent or minimise any harm or damage,

RESCAT

deterioration and loss in the future, and in consequence any invasive intervention”.  Remedial conservation is described as “actions applied directly to an asset to stop deterioration and/or harm or damages”.  Restoration: “actions conducted on a stable or stabilised asset that seek to improve its recognisability, understanding and/or use, while respecting its heritage significance and the materials and techniques used”.

In 2011, with the approval of the National Preventive Conservation Plan, the meaning of the concept of preventive conservation was set and became a fundamental criterion based on which methodologies and actions are established. The

M. José Gracia Tarragona, conservator–restorer. Coordinator of the Preventive Conservation Area of the CRBMC

31

—

During the work to track and document the site’s state of conservation.

Photo: M. José Gracia

—

—

Before and after the tasks aimed at eliminating the plants above. Photo: M. José Gracia

—

definition is expanded and preventive conservation is considered: “A strategy for conserving the cultural heritage that proposes a systematic working method to identify, evaluate, detect and control the risks of deterioration of objects, collections and, by extension, any cultural asset. Its fundamental objective is to eliminate or minimise these risks by acting at the root of the problems, which generally lie in factors external to the cultural assets, and to thus prevent their deterioration or loss and the need to undertake drastic and costly treatments applied to the assets themselves”.

From the start, the principles of preventive conservation have been grounded on the exchange of knowledge, scientific information and training. The preventive conservation strategy adopted in 2011 encompasses aspects like sustainability, resource optimisation and the accessibility of the heritage. The ultimate goal is to control risks and act at the root of the problem, not its effects on the assets. It is an essential shift in strategy. It was gradually implemented as a

centrederestauracio.gencat.cat

RESCAT

Index

32

Centre de Restauració de Béns Mobles de Catalunya

conservation of this space, which will also help set a calendar, assign priority and budget the site’s different needs with coordinated efforts and resources. Currently, the pandemic has slowed down the pace of work but not stopped it.

It was created with the desire for standardisation, to use internationally recognised methodologies and terminology on conservation matters, and with the goal of fostering knowledge transfer and dissemination, so professionals and managers at other sites are able to apply the lessons learned, and vice-versa.

To accomplish this, it requires the involvement of all the stakeholders associated with the site.

Interdisciplinary teams, rational methodologies and constant budgetary allocations are needed.

The objective is to develop a consensual strategy and to establish priorities based on corroborated and quantified studies and data (not only observation and experience). We are working with the goal of achieving comprehensive management of the site’s conservation.

What is the working method of the Preventive Conservation Plan (PCP)?

The working methodology to develop a PCP is based on 4 phases: 1. Documentation analysis of the cultural asset and its context.

2. Risk analysis: identification, valuation, definition of priorities and proposal of urgent interventions.

—

Close-up of the location of the device to track humidity and temperature data. Photo: M. José Gracia

—

RESCAT

3. Design and implementation of procedures and protocols: proposals for operation; systematic working procedures; maintenance protocols; detection and response mechanisms to emergencies; and proposals for corrective measures (remedial and preventive). strategy in the general policies and plans, and this steady upswing in implementation has also reached our sites.

Aware of the importance of and need for this change, the Centre for the Restoration of Artefacts of Catalonia has been working for several years to develop preventive conservation strategies which are advancing parallel to the remedial conservation and restoration work which was already being undertaken. We are still in the early stages, and we are making slow but steady progress.

Since 2019, we have been working to develop the Preventive Conservation Plan of the site of the Roman villa of Els Munts. The plan aims to be a tool to coordinate all the tasks associated with the

4. Verification As mentioned above, we are in a very early stage of the Plan. We are working simultaneously on phases 1 and 2. On the one hand, we are arranging the existing information: graphic documentation, reports, studies and analyses, everything associated with the site’s conservation and restoration. On the other, a diagnosis of the state of conservation and a risk assessment are being conducted, and a tool is being conceived in order to integrate and interrelate all this information.

The risk assessment and identification of the agents causing deterioration are fundamental Being able to recognise the likelihood that a certain deterioration may appear given a spe-

33

cific alteration agent (risk) and controlling these agents will enable us to prevent and anticipate damage and thus lower the interventions on the elements.

In this sense, monitoring has startedto track the agents detected and the damage they may cause.

Additionally, in recent years resources have been allocated to conduct a series of complementary studies, including: 1. Photogrammetry of the crypto-porch and the 6 rooms in the domus next to it, and mapping pathologies and risk zones 2. Study of salts: • Determination of the mineralogical composition of the efflorescence via X-ray diffraction with an X’pert Pro MRD diffractometer and specific measuring software 3. Study and identification of mortar: • Granulometric study • Determination of the mineralogical composition of the adhesive and the fine sand (size fraction under 0.063 mm) • Determination of the degree of hydraulicity of an adhesive • Determination of the open porosity and apparent and relative density of each mortar according to the UNE-EN 83980:2014 standard • Advice and proposals for new mortars for restoration 4. Study to identify the most appropriate material to remove the protective layers applied to the murals (mostly Paraloid® B72) 5. Study of the conductivity of the walls • Measurement of the conductivity of the walls via agarose disks • Mapping the data taken on the orthophotographs of the walls studied

that the agent of deterioration with the most harmful effects on the site right now is water. Its effects are the main direct or indirect cause of the majority of pathologies detected.

There are also plans for a new roof, long called for, which apparently is finally going to be made, albeit partially.

All this knowledge will be used to develop a rigorous maintenance plan. The programme will entail drawing up a series of documents which will be used to organise the periodic actions that must be made and that ensure control over the actions implemented. This programme will also include protocols on public uses and management, safety, control of vegetation, etc.

Obviously the preventive conservation proposals do not halt the other projects planned, and remedial conservation and restoration tasks continue to be undertaken. Preventive conservation is necessarily associated with remedial conservation, given that to prevent certain risks and improve resistance to the agent of deterioration, sometimes interventions are needed on elements and/or structures.

A variety of urgent interventions have been made to stabilise elements in the site, which are joined by restoration of the wall claddings and mosaics conserved in the crypto-porch.

The need for action is general throughout the entire site, but for the time being the efforts have focused particularly on acting in the zone of the crypto-porch and the rooms adjacent to the domus, with occasional interventions in the reservoir known as “la Tartana” and in the Mithraeum as well.

We will continue to develop the Plan, and we also hope to augment the monetary, material and human resources.

In turn, the National Archaeology Museum of Tarragona (MNAT) has undertaken a study on rainwater, which is extremely important given

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: site | DATE/ERA: Roman, from the 1st century BC to the 7th century AD | LOCATION: National Archaeology Museum of Tarragona. Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 14145 | CATALOGUING: Archaeological ensemble of Tàrraco declared UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

34

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

ALEIX BARBERÀ-GINÉ, SÍLVIA LLOBET, SÍLVIA MARÍN, JAIME SALGUERO and PERE ROVIRA

Previous studies for the conservation of the decorative mural paintings in the Roman villa of Els Munts.

The conservation problem of mural paintings in situ in outdoor environments

THE ROMAN VILLA OF ELS MUNTS IS ONE OF THE MOST IMPORTANT ROMAN SITES IN CATALONIA, and presents occupation structures ranging from the 1st century BC until the 7th century AD. This is a rich villa, profusely decorated with mosaics and mural paintings, intended for the leisure of the elites from the nearby capital of Tarraco. It consists of several sectors: the residential area itself (with rooms, triclinium, peristyle, etc.), the baths area, a garden area or hortus, a Mithraeum, an ambulacrum that connects the various sectors and an industrial area with several water tanks.

The residential area, from the high imperial period, consisted of a large peristyle and a two-storey building, of which only the semi-underground or cryptoportico area has been partially preserved, formed by a corridor with annex rooms. This space houses the group of most important Roman mural paintings currently preserved in situ in Catalonia.

Background Excavations of the villa’s residential area began in the 1990s, and this is when this group of mural paintings that decorate a wide long corridor and five of the cryptoportico annex rooms were discovered. During the excavation, and to protect the paintings, they were bevelled with various

RESCAT

types of mortars, and were protected by placing cloths adhered with resin, following common practice.

Furthermore, and aware of the importance of the uncovered ensemble, a temporary cover was placed to protect it from rainfall. However, after a short time, important signs of deterioration began to appear, associated with the presence of soluble salts which, due to their disruptive action, were disintegrating both the mosaic and the mural paintings. On occasion, several restoration interventions have been carried out to stabilise the ensemble, but to date they have not been able to guarantee the conservation of the mural paintings or to stop their deterioration.

At the end of 2018, in view of the pronounced and constant deterioration of the ensemble, the need arose to develop a project and prior studies that allow us to know the exact origin of the deterioration that affects the paintings, and suggest evidence-based solutions. This study has included a 3D survey, using photogrammetry of the whole ensemble; obtaining orthophotographs; making alteration maps; sample extraction and analysis (both of the paints and alteration indicators); cleaning tests; desalination tests and documentary research and cataloguing of previous interventions. The team of professionals who took part, under the guidance of the CRBMC, included: Aleix Barberà-Giné, M. José Gracia,

Aleix Barberà-Giné, conservator-restorer of cultural artefacts Sílvia Llobet, conservator-restorer of cultural artefacts (Àbac, SL) Sílvia Marín, conservator-restorer of cultural artefacts Jaime Salguero, conservator-restorer of cultural artefacts Pere Rovira, conservator-restorer, coordinator of the Area of Mural Painting, Stone Sculpture and Archaeology

35

—

General overview of the cryptoportico of the residential area of the Roman villa of Els Munts, where the mural paintings and mosaic have been preserved.

Photo: Silvia Marín

—

—

Detail of the deteriorated surface of the mural paintings. The presence of a resin on the surface exposed to the weather causes small tears and losses in the pictorial layer. Photo: Aleix Barberà-Giné

— Sílvia Llobet, Silvia Marín, Antònia Navarro, Pere Rovira, Jaime Salguero and Ricardo Suárez.

3D survey with photogrammetry and alteration maps Photogrammetry allowed us to fully document the state of conservation of the ensemble at that time, and to carry out a study and analysis of the damage, both to the paintings in the rooms and to the mosaic.

For the 3D survey, a total of 4,953 photos were taken with the Sony a7RII camera, with a full frame size CMOS sensor with 42.4 mega-pixels, Sony Zeiss Planar T fe 50mm lens, indirect natural light, metric scales for sizing damage, and SpyderCheckr colour chart for colour and exposure management.

Independent 3D photo-models of the six polychrome rooms, the cistern, the annex rooms, the painted walls in the cryptoportico and the mosaic were obtained. An original of each photo-model is saved in OBJ format, approximately 30 million faces, to have a detailed reference at volumetric level and thus be able to control the appearance of future alterations, such as separation of preparation layers, superficial deformations or collapsing walls.

In the case of the mosaic, a digital elevation model (DEM) and virtual flush light treatments were also carried out to study the relief distor-

centrederestauracio.gencat.cat

tions and the wear of the mosaic tiles in very specific areas.

At the same time, a 3D photo-model of the entire archaeological site was also generated, to obtain general and up-to-date documentation, without the current cover that protects it.

From the different photogrammetries, orthoimages were obtained at scale and in high quality (0.3 pixels per millimetre) of each of the paintings in the rooms, as well as the mosaic. This allowed us to have accurate and quantifiable documentation of the losses and wear to the different layers of the mural painting, to determine endangered

RESCAT

Index

36

Centre de Restauració de Béns Mobles de Catalunya

—

Photogrammetric model obtained individually for room 4600.

Author: Jaime Salguero

— —

One of the alteration maps made from the orthophotographs obtained through photogrammetry, on one of the walls of room 4600. Author: Jaime Salguero

—

Key Erosion of pictorial layer Loss of pictorial layer Loss of preparation layer Efflorescences of soluble salts Biological attack

areas, the appearance of efflorescences and soluble salts or biological attacks.

This valuable graphic documentation obtained allowed us to draw up very precise alteration maps, which made it possible to see these pathologies globally and to locate the most affected areas of the ensemble. Thus, it was possible to study the potential causes of the appearance of soluble salts and the consequent deterioration of the mural paintings and the mosaic tiles.

RESCAT

Analytical characterisation of materials To characterise the mortars used to make the mural paintings, the mosaic of the cryptoportico and the paintings of a room in the domus, as well as discover the mineral composition of the numerous efflorescences that are documented in this area, an initial study was commissioned to the Materials Laboratory at the Escola Politècnica Superior d’Edificació de Barcelona ( EPSEB-UPC).

Samples were taken from three points with efflorescences: from a mosaic ceramic tile, from the middle of the east wall of the cryptoportico and from the mural painting of one of the rooms in the domus. Since the site is located next to the sea, initially it could seem that they were sodium

37

—

FTIR spectrum of saline efflorescence analysis compared to the sodium sulphate pattern.

X-ray diffraction corroborated that the crystalline form corresponds to thenardite

—

M5T sample Sodium sulphate pattern

chlorides. The study of efflorescences was done with X-ray diffraction, and the results point to the presence of sodium carbonates on the mosaic and mural painting of the cryptoportico, in particular thermonatrite (Na2CO3H2O), gaylussite (Na2Ca(CO3)25H2O) and trona (Na3H(CO3)2(H2O)2).

However, the analyses determined that almost all of the soluble salts present were thenardite (Na2SO4), a very hygroscopic and especially aggressive type of sodium sulphate, because it can increase up to 400 times its volume during its crystallization, with changes due to environmental humidity. This data introduced us to a much more aggressive type of salt than sodium chloride. Also, the study of the preparation mortars of the pictorial layers, both in the cryptoportico and the domus, identified chlorides, halite NaCl in particular.

The mortar granularity study was performed through dry disintegration and sieving, and the conglomerate composition was determined by X-ray diffraction and gravitational thermal analysis. It has been confirmed that the conglomerate is aerial lime and that the aggregates are of mixed siliceous and calcareous composition, with angular shapes and a maximum grain size of 8 mm. The mortar weight of the cryptoportico paintings is 1:4 and that of the domus room paint is 1:2. Furthermore, the mosaic preparation mortar has similar characteristics, although the mortar weight is 1:3.

centrederestauracio.gencat.cat

—

Detail of the disruptive effect on the pictorial layer that generates the presence of soluble salts in the support.

The constant crystallization cycles of the salts disintegrate the mural paintings. Photo: Aleix Barberà-Giné

—

Given the serious salt problems that were documented in all the structures preserved in the villa, the CRBMC physiochemical analysis laboratory extended the sampling and study. 38 samples of domus, peristyle, Castel and Tartana and southern bath deposits were analysed, with the presence of sodium sulphate being very widespread, although sodium carbonate and chlorides were also identified throughout. At the same time, 11 soil samples were taken from the site surroundings, which were identified as calcium carbonate, aluminosilicates and chlorides.

Study of the contents of soluble salts One of the causes of deterioration that most seriously compromises the conservation of mural paintings is the presence of soluble salts in the substrate and their cyclical disruptive effect.

Before starting a new conservation intervention, we considered it necessary to carry out a study to identify the types of soluble salts and evaluate their distribution in the facings, to check the level of impact that their presence had on the integrity of the paintings.

To study the soluble salt contents in the facings it is worth bearing in mind that this is a complex approach for several reasons. First of all,

RESCAT

Index

38

Centre de Restauració de Béns Mobles de Catalunya

because the soluble salt contents varies depending on the environmental conditions and the source of the salts. Secondly, because the salt contents also changes depending on the intrinsic characteristics of the facing, such as porosity, composition or possible materials added in prior interventions, so that it does not provide a homogeneous and regular response on its entire surface. And, ultimately, because any method to obtain a soluble salt content value will have technical limitations regarding the equipment used, the degree of dissolution of the salts extracted and other technical and methodological conditions.

Aware of these limitations, the intention of the study was to obtain systematic and comparable data, which could provide information on salt distribution patterns in the wall and be repeated over time. The possibility of extracting quantitative values, although relative to the previously mentioned factors, would allow us to evaluate the relationship between the paintings’ state of conservation and the temporary concentration of salts located at each point of analysis.

The methodology used to obtain the soluble salt value is based on conductivity tests with agarose. The analyses were carried out with the application of 5% Panreac® agarose discs in deionised water, which were applied for 20 minutes on the surface of the paintings, previously moistened with a drop of deionised water.

Quantitative extraction of soluble salts was analysed with the Horiba® LAQUAtwin EC11 conductivity meter. The analyses were carried out systematically every 30 cm on the facing, but the distance could have been modified if deemed necessary. The values obtained were transferred to tables, and to make interpreting the results

RESCAT

—

Sample of the working method for the content analysis of soluble salts. The whole facing was divided with string into a 30-centimetre grid, and agarose discs were applied to the intersections, which after 20 minutes would be analysed with a conductivity meter.

Photo: Aleix Barberà-Giné

—

—

Statistical colour map with the conductivity results of the facings of room 4600, in which the uneven distribution of the salt concentration in the facings is observed. Below are the measurement points for reference that allow it to be repeated. Author: Jaime Salguero

—

39

LECTURESCONDUCTIVITY CORREGIDES DE CONDUCTIVITAT CORRECTED READINGS. ROOM - HABITACIÓ A

easier, colour statistical maps were also made to enable tracking and comparison with alteration maps.

The use of colour statistical maps is a graphic identification system that, apart from the quantitative value of salts (which is what changes depending on the different variables mentioned), gives us the areas of greatest risk, that is, with higher salt concentration. Unfortunately, the usefulness of this work methodology was corroborated only after three months, when new paint losses were identified within the systematic ensemble control and evaluation system. All alterations that occurred in the following months coincided with areas that had previously been identified as being of particular risk. Thus, we can anticipate the most sensitive areas within the same wall and define intervention priorities based on the relative values obtained. Further-

—

Table with conductivity results for room 4600 of the cryptoportico. The values have the corrected conductivity value (rest of the initial conductivity value of the agarose). Author: Aleix Barberà-Giné

— centrederestauracio.gencat.cat

B

C

D

E

1

763

663

433

783

2

1073

463

303

563

3

6873

773

783

793

F

4

433

743

883

1043

5

3073

4573

1593

903

6

923

5773

1493

833

7

573

1863

1413

503

953

933

8

953

8953

763

733

533

523

9

3173

383

553

683

993

933

10

923

693

343

813

2173

393

11

313

643

433

673

643

12

443

833

763

443

443

1223

13

963

673

343

423

523

343

14

283

303

1083

533

443

523

15

833

543

613

563

453

603

16

973

1013

933

423

353

413

17

513

373

1073

433

613

433

18

6573

723

783

363

393

523

19

273

1773

1343

863

393

243

20

1133

1573

4073

933

1473

833

21

363

1743

1973

2373

733

1633

22

633

2273

763

2073

1173

653

23

543

3473

1223

1043

643

633

24

393

463

503

543

403

193

25

433

1433

453

853

553

393

26

873

823

1493

313

323

493

27

393

503

503

433

513

323

28

853

573

523

473

513

603

29

833

903

203

673

303

263

30

713

363

253

593

553

353

31

1343

753

203

313

318

213

32

5073

623

323

353

193

303

33

6373

613

663

493

563

713

34

3473

993

413

403

633

35

1823

423

203

403

36

683

433

163

243

37

1973

523

393

313

38

6573

473

39

3273

733

40

643

493

41

1593

663

693

2 2 Valueson where therestat 127 µS/cm ofµS/cm agarose gelgel have been subtracted before applying it **Valors s’han els 127 del d’agarosa abans d’haver-lo aplicat.

TOTAL MESURES TOTAL:: 209 MEASUREMENTS

1

RESCAT

Index

40

Centre de Restauració de Béns Mobles de Catalunya

Surface deposits

Concretions

Paraloid B72 layer

Pictorial layer: fresco or dry polychrome Preparation layer: lime mortar

—

Stratigraphic scheme of the surface layers on the mural paintings. Author: Aleix Barberà-Giné

—

FTIR spectrum sample calcium carbonate pattern Paraloid® B72 pattern

more, it also allows us to monitor the long-term progression of the distribution of soluble salt contents, if the operation is repeated at different times or before and after a desalination intervention.

Then again, to assess the real-time effect on the paintings we placed a camera that videorecorded the paintings for 20 days in a timelapse, with data captured every 5 minutes. In the video obtained we can see how the salts crystallize in efflorescences on the surface of the paintings and re-dissolve almost immediately in daily periodic cycles. Efflorescences form during the warmest and driest times of the day, while they solubilise during the wettest and coldest periods. This visual tracking is complemented with the placement of a weather station to measure both the environmental and surface temperature and relative humidity. Thus, we will know exactly during which environmental ranges salts begin to crystallise and, therefore, the paintings begin to deteriorate.

In relation to the source of these salts, which is essential for their subsequent treatment, we ruled out that they could come from the sea, as thenardite is not a common salt in seawater. We also ruled out its origin in the subsoil through the extraction and analysis of multiple soil samples.

No sodium sulphates were identified in any of the subsoil points analysed on-site. Mortars applied in previous interventions were also analysed.

Sodium sulphates were also not identified in the

RESCAT

vast majority, but gypsum, i.e. calcium sulphate, was observed in some of them. It is possible that several mortars added in previous interventions, either cement or lime, may have contained gypsum in some proportion.

As found in the specialised bibliography, the formation of sodium sulphate in calcium sulphate and sodium chloride solutions is possible, due to the formation and stability constants of the various products in aqueous solution.

Calcium sulphate is partially soluble in water and in the presence of marine sodium chloride can form sodium sulphate. Therefore, today, the main hypothesis is that the salts that affect the paintings are directly related to the application of materials added in prior interventions, in the presence of sea spray. Due to its solubility and morphology, the salt identified (thenardite) is much more aggressive and deteriorating than sodium chloride, which is why both accelerated and sustained damage has been observed over time.

In order to be effective, any treatment intended to resolve the impact of salts should include the replacement of all previously added mortars which may be susceptible to including gypsum in their composition.

Cleaning study The cleaning tests are carried out on room 4600 and aim to remove several surface layers currently covering the mural paintings, but with

—

Analysis of a sample of the pictorial layer that identifies the varnish layer as Paraloid® B72

—

41

special emphasis on removing the remains of improper materials applied during previous interventions.

The presence of a thick layer of resin that covers the mural paintings obstructs the mortar’s porosity and affects the proper circulation of steam. It is logical to think that it may be a factor that aggravates the damage caused by salts.

Then again, under the layer of resin there is a layer of deposits that irregularly covers the paintings. Therefore, completely cleaning the surface requires a double approach, which includes removing both the resin and the deposits and other layers of dirt.

both by chelation (pK3) and by dissolution (pH 4.5), and another with a safe pH, for the carbonates constituting the work (pH 8.5), but with chelating capacity (pK4). Both solutions are undoubtedly systems that could be effective in cleaning the typically archaeological carbonate and carbonate soil layer, which is under the Paraloid® B-72 layer.

A) Surface water-based cleaning tests To work in a stratified and controlled way, we first chose to assess possible water-based cleaning of the most superficial layer of dirt, before removing the acrylic resin. It should be noted that prior water-based cleaning usually facilitates the subsequent action of the solvents, in the case of having to remove a layer sensitive to organic solvents (the absence of surface dirt on the resin enables better direct contact between it and the solvents).

After taking pH and conductivity measurements in the area where the surface dirt cleaning tests are to be performed, we observed that the area has a surface pH of 7.1 and a conductivity of 650 µS/cm2. A damping solution capable of removing surface dirt (basically formed by excavation soil remnants and saline efflorescences) is required, but which does not damage the pictorial substrate. Because it is a carbonate support, the choice of a chelating agent such as sodium citrate (pKfCa-Citrate 4.68), in addition to a neutral or slightly alkaline pH (within the safety range of the wall painting and in harmony with the pH of that area of the wall) should be a safe cleaning system.

Also, other mild damping solutions, with no chelating action, are tested, such as sodium acetate. In this case, the pH of the solution is lowered to 5.5 in case removing carbonate crust or other insoluble salts is required, on the points with less presence of acrylic resin (areas that seem to have a greater presence of surface carbonates other than the pictorial layer).

Furthermore, we decided to test an effective chelating agent to seize calcium ions from a carbonate salt, such as CaCO3, thanks to its pKfCa-DTPA 10.9. Two damping solutions with chelating agent DTPA applied: one with a pH capable of enabling the removal of carbonates,

centrederestauracio.gencat.cat

—

Area where the first solubility tests of the resin layer have been performed with different solvent mixtures: 1, acetone (Fd 47); 2, 75% acetone and 25% ethanol (Fd 44); 3, 30% isoctate and 70% acetone (Fd 63); 4, benzyl alcohol (Fd 48); 5, 50% acetone and 50% benzyl alcohol (Fd 48); 6, Xylene (Fd 83). We clearly observed how among the various mixtures, acetone leaves the surface saturated, while with the rest of the combinations the Paraloid® is removed in more depth, leaving the layer of surface deposits exposed. Photo: Aleix Barberà-Giné

—

RESCAT

Index

42

Centre de Restauració de Béns Mobles de Catalunya

FTIR spectrum sample Paraloid® B72 pattern

The following tests were carried out: A. 0.5% pH 5.5 sodium acetate buffer (pH buffer solution): it barely removes surface dirt.

B. 1% pH 7 sodium citrate buffer (pH buffer solution): it removes surface dirt very effectively.

C. 1% sodium citrate + 4% pH 4.5 DTPA buffer (pH buffer solution): it effectively removes surface dirt and appears to remove carbonate sediment residues in places where there is little or no resin present. Still, it does not seem to affect the pictorial layer since we do not observe colour removal.

D. 1% sodium borate + 4% pH 8.5 DTPA buffer (pH buffer solution): it effectively removes surface dirt and appears to remove carbonate sediment residues in places where there is little or no resin present. Still, it does not seem to affect the pictorial layer, since we do not observe colour removal.

E. Repetition of B (1% sodium citrate at pH 7) on an area with little or no resin layer: it removes surface dirt very effectively while not removing colour or attacking the original surface.

F. Repetition of D (1% sodium borate + 4% pH 8.5 DTPA) on an area with little or no resin layer present: it very effectively removes surface dirt and also carbonate crusts, while not removing colour or attacking the original surface.

As a conclusion for this first surface dirt cleaning, the 1% sodium citrate buffer solution at pH 7 is effective and harmless for mural paintings. Even for the final cleaning proposal, the buffer concentration could be reduced to 0.2 0.5% until reaching isotonic conductivity with the surface of around 800 µS/cm2.

B) Solubility tests with solvents The resin was identified with FTIR as Paraloid® B-72 and the approach to its removal, according to usual logic, is based on the use of solvents.

According to common practice for resin removal,

RESCAT

—

FTIR spectroscopy analysis of a sample of the pictorial layer that had been cleaned with acetone to remove the resin layer. Its peaks are clearly identifiable with the analysis, so we concluded that there is a large amount of residue with this work method

—

the first tests were based on the use of solvents (see table) to determine their solubility range based on the combination of various mixtures of isoctane, acetone and ethanol, and testing with other common solvents.

Paraloid®B-72 still showed high reversibility in solvents in which it is usually soluble.

Based on initial tests, we observed that while acetone seemed to achieve more satisfactory aesthetic results compared to other solvent mixtures, it was probably because it did not completely remove Paraloid®B-72. In fact, analysis with FTIR spectroscopy of samples cleaned with acetone still showed very significant signs of resin. All other solvent mixtures manage to remove the resin more effectively, exposing a white layer of deposits, probably carbonate, and a less satisfactory visual result.

It should be noted that all the solvent mixtures tested take on a greater or lesser degree of colour in the range of dark reds, probably because the nature of the pigment makes them more sensitive. The possibility of treating these areas

Results of the removal of resin with solvents Solvent

Fd

Saturation

Removal

Evaporation

Color

Acetone

47

Yes

Superficial

Very fast

It removes red

AE1

44

No

More effective

Fast

It removes red

IA7

63

No

More effective

Moderate

It removes red

Benzyl alcohol

48

No

More effective

Very slow

It removes red

Acetone: BeOH

48

No

More effective

Slow

It removes red

Xylene

83

No

More effective

Very slow

It removes red

43

—

Observation with Dinolite® digital microscope (x10) before and after removing the resin layer with free solvents. We observed bright points of residues that could not be removed with the work method. Photo: Aleix Barberà-Giné

— individually should be assessed. This colour removal is probably not due to the fact that the solvent can be aggressive to the paint layer, but because the original application of Paraloid® B-72 fixed dusty particles that, when removed, disappear with the solvents.

At a macroscopic level, removal of the resin using solvents seemed an effective and relatively fast method. However, observing samples with a digital microscope verified that, despite having removed most of the surface resin, there was still residue in pores and cracks. The risk of finding residues in hard-to-reach areas or even the danger of the resin re-entering the porous system of the mural painting was verified with FTIR analysis. We thus found that it was appropriate to choose another working methodology.

The next consideration could be the use of gel solvents, but traditional gel surfactant solvents are not stable on ionic surfaces. Therefore, given the large amount of salts present in the paintings, they were ruled out. In addition, they also involve

—

Working process for a cleaning test with polymeric emulsions with xanthan gum.

Photo: Aleix Barberà-Giné

— centrederestauracio.gencat.cat

the use of free solvents for removal (i.e. solvents that are not applied as gels or emulsions, such as those applied with a cotton swab or brush).

C) Cleaning with gel emulsions Finally, we decided to remove the resin using polymeric emulsions. The use of traditional emulsions was ruled out due to the high content of surfactants they include in their formulation, which would become an added residue on the surface of the work, which we wanted to avoid.

Using an emulsion could offer many advantages to solve the specific cleaning needs of the mural paintings at Els Munts: – The resin could be removed without it re-entering the porous system of the mural painting.

- The removal of both the resin and the layer of deposits could be achieved in a single process, if the aqueous phase is formulated for this purpose.

- The use of solvent could be drastically reduced, if the work is performed in a much safer manner, both for the environment and for professionals.

- It allows us to rinse the cleaning product with water and therefore basically use water-based cleaning to remove the resin.

- Since the cleaning product is an emulsion without surfactants, the presence of possible residues derived from the intervention would be avoided.

For the water phase of the emulsion, we designed a solution of sodium borate at pH 8.5, with the addition of DTPA, with a total conductivity around 3,000 μS/cm2. This solution is in a safe pH range for the preservation of fresco mural paintings, but with the addition of chelating agent it is slightly able to remove thin carbonate deposits present on the pictorial layer. This

RESCAT

Index

44

Centre de Restauració de Béns Mobles de Catalunya

—

Low-light view of a cleaning test with polymeric emulsions, where we can observe the satisfactory removal of the resin layer and surface deposits, with the use, mainly, of water-based methods with the addition of only 10% of solvent.

Photo: Aleix Barberà-Giné

—

water-based phase is then gelled with 2% Vanzan® xanthan gum.

For the solvent phase of the emulsion, several options can be considered, as long as they are immiscible in water. The first option that was considered was a 1:1 mixture of acetone and benzyl alcohol, since they are solvents that have low toxicity in small amounts. The proportion of solvent in the water-based phase was about 10% and the resulting emulsion is gently applied with a brush to the mural paintings. The application time is lengthened if working with this method, since small areas of about 10 square centimetres could require around 5-10 minutes. Finally, the cleaning product is rinsed with another buffer solution.

Another solvent option that was tested was the use of Rhodiasolv Iris®, a product that is considered a “green solvent” by the manufacturer, and which has a high solvent capacity for various

—

Observation with Dinolite® digital microscope (x13) before and after removing the resin layer with polymeric emulsions.

We observed a more regular surface at cleaning level and without perceptible Paraloid® residue. Photo: Aleix Barberà-Giné

—

RESCAT

types of resins. It is a dibasic ester, based on short branched alkyl chain dicarboxylic acids.

Specifically, it is a 2-methyl dimethyl glutarate (INCI name: Dimethyl 2-methylglutarate, CAS number: 14035-94-0), presented by Solvay as a green alternative to many chlorinated organic compounds. According to Hansen’s solubility parameters (δH = 5.0; δP = 8.7) it is very close to the solubility of acetone, N-methyl-2-pyrrolidone, ethyl acetate and methyl ethyl ketone, among others.

Emulsions that incorporated only between 5 and 10% of this solvent had the same cleaning efficiency, but with a much shorter working time, less than 5 minutes. The resin removal capacity is evident at macroscopic and microscopic level, as corroborated by laboratory analyses.

Conclusions Prior studies with the participation of multiple professional profiles have been decisive in understanding the state of conservation of the paintings and the source of the causes and factors of deterioration they present. The 3D survey of the ensemble and the use of alteration plans allows us to determine an initial state of conservation of the mural paintings and mark the guidelines for their conservation-restoration. This overview of the site’s state of conservation, which has been in place for many years, is an essential guideline for monitoring the deterioration of the ensemble over time.

45

FTIR spectrum sample cleaned with BeOH emulsion Paraloid® B72 pattern

—

FTIR spectroscopy analysis of a sample of the pictorial layer that had been cleaned with a polymer emulsion with a 10% solvent phase (50% acetone - 50% benzyl alcohol). No resin residue is observed

—

—

Sample of an area cleaned with a polymeric emulsion with only 10% solvent phase and rinsed with water. With a single process, both the resin layer and the layer of carbonate deposits and surface dirt can be removed. Photo: Aleix Barberà-Giné

— When it comes to cleaning, the use of emulsions is a more efficient system for removing layers of resin on murals, because it minimises the use of solvents and prevents the re-penetration of the resin inside the pores. It also allows us to remove the resin and the layers of deposits or surface dirt. In fact, today, the choice of waterbased systems is the most sustainable, safe and environmentally-friendly solution. The removal of this resin placed many years ago is very important to maintain the walls’ proper transpiration and prevent further alterations due to the interference of soluble salts present throughout the site.

Concerning the salt content studies, the methodology for obtaining conductivity readings with agarose discs is effective, and the combination with colour statistical maps allows us to determine the areas of greatest risk in a facing.

Apparently, the presence of sodium sulphate, the main cause of deterioration, is due to the forma-

tion of a new salt, through the combination of gypsum present in some mortars and sodium chloride in sea spray. Therefore, any desalination treatment must provide for the extraction of all intervention mortars that may contain gypsum. At a strategic level, the widespread presence of these salts throughout the site is a reality, and is considered a priority given its high deteriorating effect on mural paintings and mosaic, and is confirmed as one of the main challenges at a conservation level in the coming years.

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: site | MATERIAL / TÈCNIQUE: mural painting | DATA / ERA: Roman, from the 1st century BC to the 7th century AD | LOCATION: National Archaeology Museum of Tarragona. Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: diverse | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

46

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

RUDI RANESI

The mural paintings and mosaic of the cryptoportico in the Roman villa of Els Munts

THIS ARTICLE DESCRIBES THE CONSERVATION-RESTORATION INTERVENTION OF PRESERVED CLADDING at the cryptoportico of the Roman villa of Els Munts: the mural paintings on the side facings and the mosaic flooring, the only one preserved in its place without being torn off.

The Roman villa of Els Munts dates from the high-imperial period, and has a rich architectural and decorative heritage. The cryptoportico is located in the residential area, built on the

RESCAT

southern slope of a hill facing the sea. It is a semi-underground corridor, with an L-shaped floor plan open to the west, which gave access to the private rooms of the domus. The decorative elements object of this restoration are preserved on site: the fresco mural paintings and the opus tessellatum, flooring which are the most significant decorative remains of the Els Munts site.

Before its intervention, the cryptoportico ensemble was in a poor or very poor conservation state, depending on the areas. The preserved

—

Overview of the cryptoportico after the intervention

—

Rudi Ranesi, conservator-restorer of cultural artefacts. Arcovaleno Restauro, SL

—

Partial view of the mural paintings on the south wall of the cryptoportico before and after the intervention.

We can see the recovered painted architecture, which consists of a marbled plinth and rectangular decorative panels that alternate horizontal and vertical arrangements

—

remains were affected by pathologies that altered the whole ensemble at a conservative and aesthetic level.

The main alterations were caused by environmental conditions, proximity to the sea, and a humid, saline environment; outdoor exposure determined the widespread presence of deposits of dust, dirt, and sediment, as well as animal remains such as excrement and insect nests.

But above all, water is the main cause of alterations to the ensemble; either due to direct physical action or through the effect of capillary humidities. The fibre-cement plates of the roof have broken recurrently over the years, despite being repaired again during the present intervention. This deficiency has affected the flooring and the crowning of the walls, which have been eroded where the leaks fall through. The presence of water has entailed the appearance of hardened and carbonated deposits, and a large number of saline efflorescences. Also due to biological growth, which caused various alterations, such as the root growth from plants above or the production of acids, oxalates and chromatic alterations.

The intervention aims to improve the ensemble’s conservation conditions, by stabilizing and consolidating the alterations. Recovering the aesthetic dimension has been the other axis of intervention. In this regard, special attention has been paid to cleaning operations and to the final presentation systems, which have varied according to the areas and elements, but maintaining the coherence and unity of the ensemble.

The intervention processes have been carried out alternately or simultaneously, according to

centrederestauracio.gencat.cat

47

the needs of each area, and with different treatments for the various constituent elements and materials: the fresco mural paintings and the mosaic composed of stone and ceramic tiles.

Operations have begun with mechanical cleaning to remove dust and non-adherent deposits. This same process has also served to partially remove the acrylic resin from the paintings, and has been followed by chemical cleaning using acetone, applied through impregnation using a palette and Japanese paper.

Moderately hardened deposits have been removed with the combined use of scalpel, fibreglass pencil and Wishab® sponges.

A biocidal product was then applied to reduce biological aggression, and the roots of plants present inside the plaster mortars were removed as much as possible. To remove soluble salts, the efflorescences have been mechanically removed and deionized water dressings have been applied exceptionally to areas where salts were carbonated.

Decomposed mortars have been consolidated by injecting hydraulic mortars. In the case of the paintings, material loss restoration has focused on bevelling the perimeter, sealing cracks and fissures, and filling gaps that altered the visual continuity of decorated surfaces; chromatic reintegrations have been done with watercolour, glazes or trattegio, depending on the case. As for the mosaic, loose tiles have been replaced, and to reintegrate lost areas, others have been incorporated that came from the same mosaic and that were preserved in the National Archaeological Museum of Tarragona (MNAT).

RESCAT

Index

48

Centre de Restauració de Béns Mobles de Catalunya

WALLS. P.01 SECTION

LOCATION

A-A' elevation. South-west Wall. 1:200 scale

F_073. Image before the intervention. P.01 Section

General floor plan of the Domus. 1:500 F_074. Image after the intervention. P.01 Section

ALTERATIONS

P.01 Section Elevation. Superficial alterations/Previous interventions/Breaks. 1:30 scale

P.01 Section Elevation. Breaks/Separations/Losses. 1:30 scale

INTERVENTION

P.01 Section Elevation. Removal of added mortars/Consolidation. 1:30 scale

—

Planimetry and mapping of a section of the mural paintings on the south wall. Photo: Caridad de la Peña

—

P.01 Section Elevation. Reintegration. 1:30 scale

Alterations

Intervention

superficial alterations

removal of added mortars

previous interventions

consolidation

Limestone deposits Saline efflorescences Added mortars

breaks and distortions

Fissures/cracks

separation and detachment

Fragmentation. Air bubbles Mortar disintegration Paint breakdown (powder/lifting) loss of material

Loss (polychrome/mortar)

RESCAT

Mortar removal (bevels/filled gaps)

Gap filling with PLM Fragment adhesion with PLM reintegration

Material. Lime mortar Chromatic. Retouching with watercolour

49

MOSAIC. M.06 SECTOR

LOCATION

Mosaic floor. 1:200 scale

F_095. Image before the intervention. M.06 Sector

ALTERATIONS

M.06 sector floor plan. 1:30 scale

—

Planimetry and mapping of a section of the mosaic flooring.

Author: Caridad de la Peña

—

General floor plan of the Domus. 1:500 scale

INTERVENTION

M.06 sector floor plan. 1:30 scale

Alterations superficial alterations

Saline efflorescences Carbonated deposits Calcinations/blackening separation and detachment

Disintegrated or worn tiles Lifted tiles Losses/old mortars

Intervention cleaning

Removal of deposits and added mortars consolidation

Ethyl silicate Lime mortar and sand and lifted tiles reintegration

Lime mortar and sand and new tiles

centrederestauracio.gencat.cat

RESCAT

Index

50

Centre de Restauració de Béns Mobles de Catalunya

—

Partial view of the mosaic of the cryptoportico flooring before and after the intervention

—

RESCAT

51

—

Detail of a Solomon’s knot that makes up the geometric pattern on the mosaic flooring

—

The intervention described has given great results for the cryptoportico ensemble, but the need for constant maintenance is evident, to prevent constituent materials from degrading again.

DETAILS GENERIC CLASSIFICATION: archaeology and mural painting | OBJECT: mural paintings and mosaic on the north-eastern branch of the cryptoportico in the Roman villa of Els Munts | MATERIAL/TECHNIQUE: fresco murals on lime and sand plaster (side facings) and opus tessellatum mosaic (flooring) | TITLE / TOPIC: decorative cladding; architectures painted on decorative panels (mural paintings) and geometric decorations (mosaic) | DATE/ERA: mid-1st century - first half of the 2nd century. Highimperial Roman era | SIZE: north-eastern branch of the cryptoportico: 27.50 × 3.50 m | LOCATION: side facings (mural paintings) and flooring (mosaic) of the cryptoportico located in the south-eastern sector of the site in the Roman villa of Els Munts, Altafulla (Tarragona) | CRBMC REGISTRY NO.: 10028 (mural paintings) and 10027 (mosaic) | RESTORATION: Arcovaleno Restauro, SL. Rudi Ranesi (coordinator), Davide Belfiore, Sílvia Bottaro, Maria Cardenal, Neus Casal, Lorenzo Masi and Tina Núñez. Neus Casal and Caridad de la Peña (documentation) | AUDIOVISUAL REPORT: Verònica Moragas | YEAR(S) OF THE RESTORATION: 2015-2016 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site.

2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

52

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

RUDI RANESI

The conservation of the large southern baths in the villa

WE ARE PRESENTING THE CONSERVATION-RESTORATION OF THE CLADDINGS AND ORNAMENTAL DECORATIONS conserved in 11 areas in the southern baths in the Roman villa of Els Munts. The conservation-restoration treatment was envisaged as part of the overall restoration of the southern bath complex, planned for subsequent phases.

This complex is located in the far southwest of the Roman villa site in Els Munts, and it is the most significant bath side from the high-imperial Roman era on the Iberian Peninsula. The main entrance is the porticoed ambulacrum which connected the lower baths to the domus, around which the residential zone of the villa was arranged.

The spaces conserve numerous architectural structures corresponding to the walls enclosing the spaces and the pools comprising the route

—

Overview of the natatorium pool and the frigidarium after the treatment.

Photo: Verònica Moragas

—

RESCAT

through the baths, distinguishing between the warm and cool zones. Remains of elements that used to hold up the roof are also conserved, as well as stairs, conduits, water fountains, sewers, ovens and hypocausts.

The decorative cladding which used to cover the surfaces of the walls and pavements are conserved in situ in a rather fragmentary fashion, but they hint at the sumptuousness and decorative richness of the complex. What primarily stands out on the walls is the remains of frescoed murals, as well as stone slabs from Alcover and marble veneers in different colours (which come from quarries all over the empire). On the floor, the remains of pavements with fired ceramic flooring are conserved, along with some remains of polychrome mosaics in opus tessellatum and extremely high-quality hydraulic claddings.

Rudi Ranesi, conservator-restorer of cultural objects. Arcovaleno Restauro, SL

53

—

Process of cleaning, clearing and reorganising the fired ceramic in the caldarium.

Photo: Lorenzo Masi

— —

—

The murals conserved on the far southwest of the ambulacrum (area leading to the baths) after the treatment.

Photo: Verònica Moragas

—

The conservation-restoration tasks revolved primarily around cleaning and clearing the spaces, stabilising the degradation processes suffered by the materials and improving the interpretation of the archaeological vestiges.

Most of the actions were performed on the different kinds of claddings conserved on walls and floors, and occasionally on the wall structures themselves.

Although the basic operations were similar in many regards, broadly speaking the structures with visible construction elements (ashlars and bricks) were treated differently than the walls where the cladding was conserved (such as roughcasting, mortar in opus signinum, marble veneers, mosaic tessera, stone slabs and murals).

The most important phases in the treatment can be summarised into cleaning, consolidating and replacing the material. Materials compatible with and similar to the originals were used in all cases. The procedures and application methodologies, as well as the exact composition of the materials, were determined by the results of tests conducted prior to the start of the project.

Process of recomposing the water channel which runs from the northern sector of the site to the bath area.

Photo: Maria Cardenal

—

The treatments were necessarily accompanied by constant maintenance of the entire area in order to counter the effects of the complex’s exposure to the atmospheric and environmental conditions outside.

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: bath complex: walls, pavements and different claddings, murals, mosaics and veneers | MATERIAL/TECHNIQUE: Local limestone wall structures resembling the stone from Mèdol; opus caementicium, opus vittatum, opus incertum and opus quadratum. Claddings: frescoed murals, veneer of marble and stone from Alcover, mosaics in opus signinum and opus tessellatum. Marble, bricks and ceramic tiles, lime and sand and/or crushed ceramic mortars | TITLE / TOPIC: decorative cladding | DATE/ERA: Roman era (late 1st - mid-2nd century to the 4th century) | SIZE: walls: 1,256 m2; pavements: 1,860 m2 | LOCATION: southwest side of the Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 12565 | RESTORATION: coordinator: Rudi Ranesi (Arcovaleno Restauro, SL), Neus Casal (documentation), Carlos Alías, Maria Cardenal, Gianpiero Lauriola, Lorenzo Masi and Melitón Sánchez | PHOTOGRAPHS: Verònica Moragas | YEAR OF THE RESTORATION: 2016 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

54

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

SÍLVIA LLOBET

Conservation and restoration work on the antechamber of the Mithraeum

THE MITHRAEUM IS A LARGE BUILDING constructed between the 2ND and 3RD centuries and divided into different spaces. First, there is an entrance corridor followed by an antechamber meant as a reception area and place to prepare the ritual banquet. This antechamber leads to the cave where the initiation rites and banquet were held, which reflected the architectural features of these spaces of worship: rectangular layout, central corridor and two benches built into the walls where participants could recline while eating. Lastly was the three-part worship room, only the foundations of which still remain, although it must have been presided over by an image of Mithra’s ritual killing of the bull.

Background Most of the structures of the Mithraeum were excavated between 2004 and 2005, and since then several urgent campaigns have been conducted, primarily focused on bevelling the wall claddings of the antechamber and the benches in the cave. Given the endangerment of conserving the remains, in 2019 the Centre for the Restoration of Artefacts of Catalonia (CRBMC) and the National Archaeological Museum of Tarragona (MNAT) decided to undertake the conservation and restoration of this sector via the antechamber.

The antechamber, the Mithraeum’s reception area This is a trapezoidal area measuring 29 m2. The northwest wall was the facade visible from the portico, and it was built with a baseboard of irregular stones attached with clay mortar and raised with sun-dried brick, then covered with a mural both inside and outside. The remains of the wall that is still conserved inside show a baseboard with a white background and red stripes that delimit a series of panels.

RESCAT

The northeast wall, which was only visible from the inside, is also amidst pillars made of more regular stones attached with lime mortar. The remains of the murals also have a white baseboard and red stripes which delimit panels and inter-panels with an ochre background. Finally, a bench around 60 cm wide runs along the walls, although it is currently only conserved across from the door leading to the cave, and wall claddings are conserved which largely echo the decoration of the others.

State of conservation The antechamber’s overall state of conservation was poor. There were numerous agents of deterioration, as the structures are exposed to climatic agents, most importantly rainwater. The site stretches along the western slope of Cap Roig, which projects westward to create a regular platform, where the central core of the villa was located. It spread along a slope until connecting with the southern baths via a ambulatio, to the south of which the Mithraeum was built. The Mithraeum bears the impact of the water runoff, which causes scouring problems on the claddings and the deterioration of the walls’ foundation.

The lack of a roof over the structures also led to the development of biocolonisation, such as the growth of plants on top, microorganisms and the damage caused by the presence of insects and other arthropods. Likewise, the exposure to ultraviolet radiation affects the conservation of the murals.

The walls, especially those built with clay mortar, had structural problems such as the loss of the mortar and the shift and flaking of some elements. Problems of fissures, flaking, gaps and separations between layers and disaggregation were found on the walls.

On the claddings of the Mithraeum, an accreted layer was identified which was analysed in

Sílvia Llobet, conservator-restorer of cultural artefacts. Àbac Conservació-Restauració, SL

55

—

Orthoimages of the northwest wall of the antechamber of the Mithraeum. The upper ones show the wall on the inside before and after the treatment. The lower ones show the state of the outside after the treatment.

Photo: Jaime Salguero

—

centrederestauracio.gencat.cat

—

Orthoimages of the northeast wall of the antechamber of the Mithraeum before and after the treatment.

Photo: Jaime Salguero

—

RESCAT

Index

56

Centre de Restauració de Béns Mobles de Catalunya

—

Close-ups of the state of conservation of the northeast wall with the remains of murals, and a view of the northwest on the outside. The image on the right shows the state of the southern facade and the bench in the entrance to the cave. Photo: Sílvia Llobet

—

the CRBMC’s physiochemical analysis laboratory.

According to the results, there was calcium carbonate, a clayey compound and other aluminosilicates (soil). At the same time, soluble salts were found on all the elements, which were also analysed and identified as lime, calcium carbonate and sodium sulphate.

Conservation and restoration of the antechamber The work got underway with photogrammetric documentation of the state of conservation, studying the damages and mapping the site.

The first conservation process was a biocide treatment, following by a mechanical cleaning of the walls focused on eliminating the plants and soil deposits, a laborious task on the northwest due to the large amount of construction and decorative materials that were above and around the structure, which had to be collected and packed. The soluble salts were also rubbed off.

RESCAT

Before consolidating the walls, the different original mortars were studied and the most appropriate materials to make the restoration mortars were chosen, in this case hydraulic lime and with solids that include cleaned river sand, coarse sand, pebbles and crushed pottery. All the stone elements that were added for to reinforce the structure and improve the interpretation of the complex and all the stones attached were placed over an internal fiberglass net as a separation material. Mortar was added to all the lost joint mortar and the deteriorated lower parts of the walls.

The wall claddings were cleaned, the soluble salts and microorganisms were removed from them and they were reattached to the wall with wet lime mortar and crushed pottery. Wet lime was used to make the mortars for bevelling and replacement, and the dry materials were river sand, coarse sand and pebbles for the preparatory layers, while finer solid materials were used

57

—

Close-up of the replacement of lost mortar on the outer northwest wall.

Photo: Sílvia Llobet

—

for the upper layer, such as marble powder different tones.

The stone elements in the entrance zones and door thresholds were treated with mechanical cleaning and biocide treatments, and the small flakes were stabilised and all the cracks, joints and deteriorated lower parts were fixed.

Finally, the internal circulation level of the antechamber was restored to avoid the accumulation and improper circulation of rainwater, while also protecting the lower parts of the walls and improving their presentation. A polypropylene cloth covered with up to 50 cm of crushed stone was installed, attached with a flexible PCV edge at the threshold to the cave.

Future proposals The restoration work started in the antechamber is scheduled to continue in the other structures still conserved in the Mithraeum in order to guarantee the future integrity of the space of worship. Additionally, since 2019, the CRBMC has been working on drawing up the Preventative Conservation Plan of the Villa of Els Munts, which should include preventative conservation projects, their scheduling and risks assessments and the measures to correct them. Without all of this, it will be very difficult to preserve all the structures in this unique complex that are still conserved.

—

Close-up of the consolidation of internal wall claddings. Photo: Sílvia Llobet

—

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: mural painting | MATERIAL/TECHNIQUE: lime mortar and stone | DESCRIPTION: side walls of the Mithraeum | DATE/ERA: Roman, between the 2nd and 3rd century AD | SIZE: 29 m2 | LOCATION: Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 10029 | COORDINATOR: Pere Rovira | RESTORATION: Àbac Conservació-Restauració, SL: Sílvia Llobet, Maria Molinas, Gemma Piqué, Jaime Salguero and Gemma Torra, and the interns from the CRBMC:Xavier Martínez, Marina Ramisa and Olga Schmid | YEAR OF THE RESTORATION: 2019 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

58

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

AGIT SERRANO

Consolidation of La Tartana

THE WEALTHY AND LUXURIOUS LIFE ENJOYED BY CAIUS VALERIUS AVITUS AND HIS WIFE FAUSTINA in the villa required the storage of large amounts of water, in order to cover the needs of the residence.

La Tartana is the popular name given to the remains of the water cistern, as it is reminiscent of a carriage cover. This is what remains of a construction with a barrel vault and a quadrangular floor plan, which was possibly part of a complex with more tanks. It is relatively secluded from the residential area and is built with irregular stones and pebbles grouted with lime mortar. This construction is very peculiar and identifies the site, especially because the entire vault is still preserved.

Of the four full walls that formed the alleged quadrangular structure, two are whole, which support the barrel vault; the other walls vary in height depending on the preserved segment, of maximum 90-100 cm. These walls have lost all the exterior cladding.

RESCAT

—

Remains of the old cistern (popularly known as La Tartana). Photo: Agit Serrano

—

As is well known, the Romans used opus signinum as a waterproofing coating. We find it inside, on the flooring and in fragments on the walls. Outside, the remains are very thin, but we can find them on the wall opposite the sea and in much of the perimeter covered by earth from the land that has protected it. These exterior remains give clues to the fact that it could be part of a series of annexed tanks.

In the walls that support the vault there is an old intervention made during the second half of the 20th century with stones and cement, which does not meet current restoration criteria, but which most likely has allowed the vault to be preserved today as we see it.

As for the state of conservation of the vault, externally the joint mortar vastly disappeared, to the point that there were areas where the lack of it had caused the stones that form the roof to detach. In many cases, this loss has resulted in the partial collapse of the vault. The inside of it was very deteriorated: there was joint mortar

Agit Serrano, heritage conservator-restorer. A&M Patrimoni, SCP

59

—

View one of the fragments of opus signinum from inside “La Tartana”, already consolidated on the perimeter. Photo: Agit Serrano

—

—

State of the stones inside the vault. Photo: Agit Serrano

—

missing and what remained was extremely eroded. The stones’ composition was so severely altered, that when touched they broke and fell.

They required urgent consolidation.

Our action has focused on consolidating the perimeter of the opus signinum remains and re-grouting with lime mortar, to reinforce the weakened structure that sustains an extremely deteriorated vault. This action has been the previous step to restore and consolidate the entire volume built, which still preserves the vault.

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: remains of a water cistern | MATERIAL/ TECHNIQUE: stone and lime mortar with some previous intervention made with cement | TITLE / TOPIC: popularly known as La Tartana | AUTHOR: unknown | DATE/ERA: 2nd century AD | SIZE: quadrangular floor plan: 6 × 5 m (exterior dimensions) with walls about 0.40 m thick | LOCATION: Roman villa of Els Munts, Altafulla (Tarragonès) | CRBMC REGISTRY NO.: 14038 | COORDINATOR: Pere Rovira | RESTORATION: Manuel Domínguez and Agit Serrano (A&M PATRIMONI, SCP) | YEAR OF THE RESTORATION: 2020 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site.

2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

60

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

RUDI RANESI

The large cistern at the Roman villa of Els Munts or “Castel deposit”

IN THE NORTH-EASTERN SECTOR OF THE VILLA ENCLOSURE IS THE MAIN TANK for rainwater collection, also called “Castel deposit”, which was part of the pipe system in the rustic villa, from a period before the paintings in the residential area.

Its floor plan is rectangular and is divided internally into eight compartments separated by strong walls, connected to each other through semicircular arches. It is a solid, robust structure.

The Roman concrete walls have a remarkable thickness, in this case 55 cm. They are coated with signinum hydraulic mortars, up to 4 cm thick, made of lime, sand and broken ceramic elements,

RESCAT

of different sizes. On the perimeter plinth, between the flooring and the vertical structures, there is a considerable rounded groove that prevented the accumulation of dirt in the corners, following a technique commonly used in the Roman world.

Although it is a solid structure, the state of conservation of the ensemble presented many deficiencies when starting work. These were concentrated in the coatings, both of the walls and the pillars of the cistern, given that the mortars were partially detached from the support and showed significant dents and separations, which often turned into material

—

Partial view of the cistern before the intervention.

Photo: Rudi Ranesi

—

Rudi Ranesi, conservator-restorer of cultural artefacts. Arcovaleno Restauro, SL

61

—

Overview of the cistern before the intervention. Photo: Rudi Ranesi

— centrederestauracio.gencat.cat

RESCAT

Index

62

Centre de Restauració de Béns Mobles de Catalunya

—

Plant of the main cistern at Els Munts

— —

Detail of a cistern wall showing the loss of opus signinum coating. Photo: Rudi Ranesi

—

losses. At the same time, the presence of biological agents in the form of lichens, algae and higher plants was prevalent, which could end up weakening the structures and constituent materials. Insect and animal nests (such as lizards) as well as saline efflorescences were also common.

The intervention fundamentally consisted of an urgent action to solve the most serious problems and avoid the subsequent loss of original coatings. For practical and budgetary reasons, management at the Archaeological Museum of Tarragona decided to intervene in the lowest area of the flooring and the first meter and a half of the walls (which was the most accessible area and also the most deteriorated).

We started cleaning the surfaces with brushes and brooms , and then continued with vacuum cleaners and palettes, to remove items deposited on the floor, such as dry leaves, dust and fallen stones from the outside. Cleaning allowed us to recover the original loose material, which had fallen to the ground, to reuse it in the successive reintegration phases. Biotin® T, from CTS, was applied to remove the biological

RESCAT

—

Cleaning phase with water, sponges and brushes. Photo: Rudi Ranesi

—

—

Extraction of biological elements from the cistern floor. Photo: Rudi Ranesi

—

63

—

Consolidation phase with hydraulic mortar injections.

Photo: Rudi Ranesi

—

elements, and the salts were extracted both dry and using distilled water dressings.

The deepest cleaning was done with hydroalcoholic solution and brushes, but occasionally, AB57 dressings were also applied.

The consolidation of the coatings was done with injections of CTS PLM ® hydraulic mortars, in all areas where there was a danger of falling.

Crack and fissure reintegrations were made with lime mortars and aggregates of different types, and whenever possible, with previously recovered recycled materials. In a specific case, at the base of a pillar, we had to tear off part of the coating, in order to be able to put it back in its original place, re-attach it and support it until the mortar dries.

The intervention carried out expected to include planning periodic maintenance, in order to preserve the objectives achieved in the intervention, but unfortunately financial problems have not made this possible.

—

Cleaning phase of the rounded groove area.

Photo: Rudi Ranesi

—

DETAILS GENERIC CLASSIFICATION: archaeological and palaeontological material | OBJECT: main cistern. Hydraulic coating with opus signinum | MATERIAL/TECHNIQUE: plaster made with lime, crushed ceramic elements and sand: opus signinum (flooring, side walls and pillars) | TITLE / TOPIC: main cistern, also known as “Castel deposit” | DATE/ERA: Roman era; mid1st century and first half of the 2nd century | SIZE: 21.50 × 5.5 × 3.5 m, divided into eight parts connected to each other by arches | LOCATION: northeastern side of the villa. Highest sector of the site in the Roman villa of Els Munts, Altafulla (Tarragona) | CRBMC REGISTRY NO: no number | RESTORATION: Arcovaleno Restauro, SL. Rudi Ranesi (coordinator), Davide Belfiore, Renzo Saporetti and Manuel Uzandizaga | YEAR OF THE RESTORATION: 2008

centrederestauracio.gencat.cat

RESCAT

Index

64

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

MISI BRUNED

Discovery, recovery and first intervention of the ceiling in Els Munts

THE CEILING IS PART OF THE HOUSE OF CAIUS VALERIUS AVITUS, DUUMVIR OF TARRACO, AND HIS WIFE, FAUSTINA, an important enough person to understand the characteristics and quality of the techniques used when executing the decoration. Up until now these characteristics remained unknown.

The ceiling was located in one of the secondary rooms of the domus no. 4700 during its excavations, and was in very poor condition, practically in ruins, due to the fire that caused its fall and destruction. It was very fragmented and mixed with structural remains from the living quarters, but retained its polychromy, as it was made with the fresco technique with lime paint finishes.

Although it was initially difficult to understand its structure, it is shaped like a coffered ceiling; the surface is flat and arranged in longitudinal, transversal and tangential planes, in three differentiated reliefs or levels. It presents 6 coffers: 2 quadrangular and 4 polygonal (octagonal), at various levels.

The support on which it is held up is made of several layers of trowelling of considerable thickness. These were originally made directly on a ceiling supposedly made of reeds and wood, with ropes and nails. When the ceiling fell down because of a fire, it fell to the ground, and remained there until its discovery, at which time it still remained in the room.

First, specialists in Roman paintings dated the material through chromaticity, iconographic information, and location. Also, a series of analyses confirmed that it could be dated to the 2nd century AD. Given this, it was time to consider the intervention. The boxes, with all the material, were moved to the Central Services of the National Archaeological Museum of Tarragona (MNAT), in Tarragona, in the space prepared to receive all the fragments and the team of restorers.

We found fragments made with the fresco

RESCAT

Misi Bruned, conservator-restorer of cultural artefacts. GAM Restauració, SCP

65

—

Reception of boxes at the premises of the Central Services of the National Archaeological Museum of Tarragona.

Photo: Misi Bruned

—

—

During the assembly of the fragments.

Photo: Misi Bruned

— —

Reverse. The marks of the reed and the rope can be observed. Photo: Misi Bruned

—

centrederestauracio.gencat.cat

painting technique with lime finishes, supported by two layers of plaster (plaster, sand and stone pebbles). The material did not reveal any source of moisture, but there were areas with alterations to the pictorial layer, due to fire, as well as calcifications and deposits of inorganic matter, soluble salts and occasional carbonations. Furthermore, there were also superficial fissures and deeper cracks, deformed surface layers compared to the support, as well as corners with disintegrated preparation layers. And the saddest part: significant losses of original parts. The structure of the support mortar was unstable and did not contain any moisture, which caused fragmentation and internal disintegration.

The restoration intervention is carried out in different stages. At the time of the excavation, the fragments were classified by colour, according to pictorial layer, textures and remnants of adhesives, but bearing in mind that the thickness of the mortars were not always indicative elements, since many supports had been lost.

First, we began to assemble the puzzle, a job of great difficulty that required the intervention of a team of restorers and specialised archaeologists.

Next, mobile modular counters with 15-cm high profiles were made, in which the fragments were introduced, on top of synthetic sand, which acted as a cushion to hold the pieces. This intervention was so complex, and we did not have

RESCAT

Index

66

Centre de Restauració de Béns Mobles de Catalunya

—

One of the coffers, presented. Photo: Misi Bruned

—

—

During the making of the casts, in which all the information of each of the fragments will be marked. Photo: Misi Bruned

—

—

Removal of adhesives.

Photo: Misi Bruned

— RESCAT

any information about a ceiling of this nature, that the decision was made to work the pieces upside down, to find some connection. When it was found, we understood that it was a threetiered decorative ceiling, better known as a coffered ceiling.

Casts were then made on acetate sheets, in which each fragment and its placement were marked. Next, all the information regarding the alterations to the pictorial layer was taken, especially those produced by the fire, the direction of the ropes of the reed, the types of mortars, etc.

Furthermore, work began on the fragments to stop their degradation. Initially, they were cleaned of dust and debris separately, individually. To be able to work on and handle them without harming them, they are joined with Imedio® reversible adhesive (28% cellulose nitrate and 72% ethyl acetate) and the small gaps are filled with mortar (1 with hydraulic lime + 3 with sand detached from the original mortar itself + sepiolite + Primal® AC 33). Once some fragments have been added, a first mechanical and solvent cleaning was performed (8% citric acid on the pictorial layer, where the deposit layer is thin, and with AB 57 on the most stable colours of the pictorial layer, except for the red. Some parts of mortar needed the application of a consolidating agent that penetrated well, so Tegovakon® V (monocomponent based on silicic acid esters) was used, with a magnificent result; and also Fakolit® 34 (silicate base) which was used on thick mortars.

The very powdery pictorial layer of some fragments was consolidated with 3% Paraloid® B72 with acetone.

To have a final view of the ceiling, neutral synthetic sand was used to fill the gaps and have a full visual of the ensemble, awaiting its definitive restoration.

67

—

Cleaning the red pigment required a more delicate procedure.

Photo: Misi Bruned

—

—

Final work. The gaps were filled with synthetic sand.

Photo: Misi Bruned

—

DETAILS GENERIC CLASSIFICATION: mural painting | OBJECT: ceiling | MATERIAL/TECHNIQUE: lime mortar and stone support, with fresco polychrome and dry finishes | TITLE / TOPIC:ceiling of room no. 4700 of the domus | DATE/ERA: 2nd century AD | SIZE: quadrangular floor plan of 16.10 m2 | PROVENANCE: Roman villa of Els Munts, Altafulla (Tarragonès) | LOCATION: National Archaeology Museum of Tarragona (MNAT). Central Services. Tarragona (Tarragonès) | CRBMC REGISTRY NO.: 9900 | TECHNICAL COORDINATION: Pere Rovira | RESTORATION COORDINATION: Misi Bruned (MNAT collaborator) | RESTORATION: Lorena Andino, Mireia Calaf, Núria Deu, M. Antònia Moreno, Margalida Munar, Clara Payàs, Elisenda Pedrosa, Luciana Pocostales and Cristina Pujante | ARCHAEOLOGISTS: Carmen Guiral (National University of Distance Education. UNED), Julien Boislève ( Centre d’Étude des Peintures Murales Romaines.

CEPMR) and Veronica Provenzale | YEAR OF THE RESTORATION: 2006 | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

centrederestauracio.gencat.cat

RESCAT

Index

68

Centre de Restauració de Béns Mobles de Catalunya

INNOVATION & RESEARCH

ALEIX BARBERÀ-GINÉ

Preliminary study for the Els Munts ceiling assembly system

THE CEILING FROM THE VILLA OF ELS MUNTS IS PROBABLY ONE OF THE MOST NOTABLE WORKS FROM THE ROMAN PERIOD PRESERVED IN CATALONIA. This is a unicum which allows us to discover and study this type of construction element and its decoration.

Background This is the ceiling of one of the rooms in the area of the villa’s cryptoportico, which collapsed during the second half of the 2nd century AD, due to a fire that caused the demolition of part of the northern branch of the ambulatio and annex rooms (F. Tarrats and J.A. Remolà (2007), “La vil·la romana dels Munts (Altafulla, Tarragonès), J.A. Remolà (coord.), El territori de Tarraco, vil·les romanes del Camp de Tarragona, Forum 13, Tarragona, 95-117).

This circumstance, which led to its destruction, at the same time allowed its conservation, as it remained buried for centuries, until its discovery during the archaeological excavation of room 4700, in the late 1990s. The fragments were extracted, documented and deposited in boxes in the storage rooms of the National Archaeological Museum of Tarragona (MNAT).

After an initial conservation-restoration intervention, by a team led by Misi Bruned, in 2006 many of the fragments were located and put together to reassemble the ceiling on a makeshift bed of sand.

The surface was initially cleaned, and part of the smaller pieces were adhered. In this way, it was possible to view the ceiling as a whole again.

This work is made of lime mortar, which on the reverse perfectly preserves the imprint of the reed on which the first layer of plaster was applied. It features a square frame with a central section on one level, and then two symmetrical sections of coffers on a lower level.

This distribution provides a lot of depth and relief to the ensemble. Each of the sections of coffers is arranged into three rectangular units, which inside have octagonal mouldings at the ends and square mouldings in the centre, framing female figures.

RESCAT

—

Identification of the obverse (left) and reverse (right) of the fragments on which the first study of the digitisation of the ceiling was done with an articulated arm laser scanner.

Photo: Aleix Barberà-Giné

— —

Illustrative orthophotography for knowledge of the work, which was obtained at the beginning of the study of the ceiling, based on a photogrammetry from mobile phone images. Photo: Aleix Barberà-Giné

—

Aleix Barberà-Giné, conservator-restorer of cultural artefacts

Its entire surface is fresco polychrome or with dry finishes, with geometric and figurative motifs, and the preparation layers that conform the ceiling are made in varying thicknesses, to achieve the different levels and mouldings.

Assessment of the different assembly system possibilities When considering the definitive assembly system, the historical importance of both the obverse and the reverse of the work is assessed for study. The details of the reed imprints are a testament to the construction technique that should be preserved, as well as the entire thickness of mortars that make up its structure.

For this reason, a first possible structure was considered in which each of the fragments of the ceiling rested on a countermould of the work, obtained directly from the reverse of the ceiling itself and which, therefore, adapted perfectly to it.

Although it was a system that included minimal intervention and strict reversibility, the large dimensions of the ceiling, its considerable weight and the large number of fragments that make it up entailed a complex intervention. But the fact that the reverse of the fragments are very irregular and have losses made it infeasible to make a mould of this surface, as the pieces would be stuck without possibility of removal and there would be a risk of

centrederestauracio.gencat.cat

69

damage to the original work. This is why this option was ruled out.

As an alternative to this traditional solution, we considered the possibility of using 3D technologies to design the same presentation system, based on a new support that adapts to the reverse of the ceiling and supports each of the fragments, but this time printed in 3D. The proposal essentially consists of assembling the ceiling upside down, digitising the reverse and printing a custom countermould. The main difference would be that, in this case, it is not necessary to apply any product directly to the work.

To assess the viability of this option, we decided to make a small test on some fragments of the ceiling. We decided to digitise the reverse of a small area of the ceiling, which corresponds to a total of 28 small fragments, many of which are attached, which form a total of 9 distinguishable units.

Among the various options for 3D digitisation is the FARO® 7-Axis Design ScanArm 2.5C arm laser scanner with FARO PRIZM Laser Line Probe laser probe and 40 micron point separation, with an accuracy of at least 75 microns. This equipment was chosen to achieve the maximum geometric accuracy possible and the real size of the model, given that any variation, no matter how small, could compromise the final result .

RESCAT

Index

70

Centre de Restauració de Béns Mobles de Catalunya

—

During the 3D digitisation process with the Faro® Design ScanArm scanner. Photo: Aleix BarberàGiné

— The model obtained was digitally processed to be 3D-printed, with Ender3 Pro printer with PLA material, at a layer resolution of 0.1 mm, and we requested the creation of a mould of the milled reverse, with numerical control on high density polystyrene foam, to assess whether a good fit was achieved.

For this reason, a budget was requested from several numerical control milling companies, to print the countermould in a resolution of around 1 mm, taking into account the high level of detail and geometry of the reverse. The budgets presented far exceeded what would be reasonable if the same process were to be carried out on the entire ceiling surface area.

The main conclusion reached is that this working methodology would be completely reversible and would guarantee minimum intervention on the ceiling. It would allow us to have 3D documentation of the reverse of the work for scientific consultation, and at the same time assemble each of the fragments in their original location, without the need for any adhesive or mortar. However, its application on an extremely irregular reverse and such a large format, today involves disproportionate production costs for the intended result.

Finally, the solution presented contemplated the digitisation of the ceiling with photogrammetry, both the reverse and the obverse, using fragments or units. In this way, the documentation and accessibility to the historical information offered by the reverse of the work is guaranteed.

Furthermore, we proposed applying a minimum layer of lime mortar to regularise the reverse of the fragments, with an interposition of Japanese paper to minimise adhesion and facilitate eventual extraction. The aim was to create a regular surface on the reverse, which would support the ceiling in several sets of fragments. The layer of lime mortar should be of the minimum possible thickness, to stabilise and join the various fragments, and that these could be manipulated for assembly on a foam bed in an aluminium structure.

—

3D model obtained with photogrammetry during the last phase of the ceiling restoration, by the company Arcovaleno Restauro, SL. The photogrammetry was obtained from images by the photographer of the National Archaeological Museum of Tarragona, Gemma Jové.

—

The model can be viewed at the following link: https://sketchfab.com/3d-models/sostre-dels-munts -d05-57750e18d85f45068179c5e279353af9

DETAILS GENERIC CLASSIFICATION: archaeological material | OBJECT: ceiling | MATERIAL / TECHNIQUE: tone support and fresco polychrome lime mortar or with dry finishes | TITLE / TOPIC: ceiling of room no. 4700 of the domus | DATE/ERA: 2nd century AD SIZE: 4.60 × 3.50 m approximately | PROVENANCE: Roman villa of Els Munts, Altafulla (Tarragonès) | LOCATION: National Archaeological Museum of Tarragona (Tarragonès): Central Services | CRBMC REGISTRY NO.: 9900 | COORDINATOR: Pere Rovira | STUDY: Aleix Barberà-Giné | CATALOGUING: Archaeological ensemble of Tàrraco declared a UNESCO Human Heritage Site. 2000. Cataloguing BCIN 2044-ZA

RESCAT

A MUST-READ

Diagnóstico por imagen en bandas no visibles sobre patrimonio cultural. Una aproximación a la imagen infraroja, ultravioleta, fluorescencias y análisis de imagen (Diagnosis of the Cultural Heritage with Images in Invisible Bandwidths: An Approach to Infrared and Ultraviolet Images, Fluorescence and Image Analysis) José Manuel Pereira Uzal Books upon request: José Manuel Pereira Uzal (Ed.) As a chemist, it can be difficult to talk about technical concepts with some professionals without them looking at you as if you're speaking a different language.

Oftentimes, words like electromagnetic radiation, wave length (λ), characteristic spectrum, hotmirror, reflectography, Stokes shift, multispectral image and others are as disconcerting as a cryptogram.

The book, self-published by the author, provides an entertaining explanation of the physical foundations of the invisible electromagnetic spectrum, that is, the part that our eyes cannot see. It contains information on the instruments used to capture images, such as the sensors used in different ranges of the electromagnetic spectrum; basic concepts of modified DSLR cameras (common cameras which can be modified to achieve the complete sensitivity of a sensor in the electromagnetic spectrum; choices of lenses; calibration; and available light sources.

With regard to the foundations of images in invisible bandwidths, Pereira introduces us to the representative concepts of images in the infrared and ultraviolet regions, thermography and multispectral imaging, all accompanied by graphic illustrations and colour images.

We hope that Books on demand GmbH (BoD) always respected the high quality and dedication that José Pereira puts into his work, and we want to thank him for writing this book in Spanish.

71

La conservación del arte contemporáneo (The Conservation of Contemporary Art) Sonia Santos Gijón: Ediciones Trea, SL, 2017, 95 p.

Sonia Santos teaches in the Department of Painting and Conservation-Restoration in the Fine Arts Faculty at the Complutense University of Madrid and holds a PhD in Fine Arts with a specialisation in Conservation and Restoration.

In this publication, she discusses the challenge of conserving contemporary art. The book is divided into two parts.

The first one examines the criteria used, the cornerstone of any intervention, and the second surveys the issue of the conservation-restoration of synthetic polymers and metals.

What I found the most interesting in the book, and what I would have liked a lengthier discussion of, is real cases illustrating the problems of different criteria posed by the diversity of types of contemporary art. For example, conserving a work of eat art forces us to resolve certain issues that may differ greatly from those posed by a video installation or an outdoor sculpture.

Santos explains that traditional intervention criteria often clash with the artist’s desires, and she draws from practical cases to show how this has been resolved in certain situations. She also briefly introduces the extremely important topic of copyright, which is essential to be familiar with and always bear in mind in an intervention of this kind.

In the second part, she discusses the conservation-restoration of cultural assets made with synthetic polymers and metal, focusing on two categories of materials commonly found in contemporary art. She describes the materials, explains why they deteriorate and shares several examples of conservationrestoration treatments.

Esther Gual, conservator of cultural assets. CRBMC

Ricardo Suárez, chemist at CRBMC

centrederestauracio.gencat.cat

RESCAT

CRBMC. CENTRE DE RESTAURACIÓ DE BÉNS MOBLES DE CATALUNYA C. Arnau Cadell, 30 – 08197 Valldoreix Tel. 935 902 970 – Fax 935 902 971 crbmc.cultura@gencat.cat https://centrederestauracio.gencat.cat www.facebook.com/RestauraCat www.instagram.com/restaura.cat

PUBLISHED BY Ministry of Culture of the Government of Catalonia MANAGEMENT Àngels Solé EDITORIAL BOARD Esther Gual, Josep Paret, Àngels Planell, Pere Rovira,

Mònica Salas, Àngels Solé and Maite Toneu OVERALL COORDINATION Àngels Planell TEXTS The authors COPY EDITING Àngels Planell and Incyta Multilanguage PHOTOGRAPHY Ramon Maroto (CRBMC) and the authors themselves DOCUMENTATION Maria Ferreiro, Àngels Planell and Mònica Salas PHYSICOCHEMICAL ANALYSIS LABORATORY AND ANALYSIS PHOTOGRAPHY Ricardo Suárez X-RAY LABORATORY Esther Gual ORIGINAL GRAPHIC DESIGN ciklic TRANSLATION STAR Servicios Lingüísticos FRONT COVER PHOTO Ceiling of one of the rooms at the cryptoportico, in the area of the roman villa of Els Munts. Orthophotography for knowledge of the work Photo: Aleix Barberà-Giné LEGAL DEPOSIT B-13.856-2012 ISSN ONLINE EDITION 2013-3251 Key Title: Rescat (Barcelona, Internet) Abridged title: Rescat (Barc., Internet)

Generalitat de Catalunya Departament de Cultura