The ceiling preliminary study

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.

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

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 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 .

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.

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

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.

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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

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 ( ), 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.

Ricardo Suárez, chemist at CRBMC

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

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)