Educational Linkage Approach In Cultural Heritage Prof. Antonia Moropoulou - NTUA – National Technical University of Athen...
Prof. Antonia Moropoulou - NTUA – National Technical University of Athens  Copyright  ©ELAICH Beneficiaries 2009-2012 This...
Prof. Antonia Moropoulou - NTUA – National Technical University of Athens  Abstract The current presentation examines one ...
Prof. Antonia Moropoulou - NTUA – National Technical University of Athens  Content Educational Linkage Approach In Cultura...
Educational Linkage Approach In Cultural Heritage   2.6.1. Definition of mosaics Prof. Antonia Moropoulou – Topic 2.6: Mos...
Educational Linkage Approach In Cultural Heritage   2.6.2. Tesserae Type of mosaics based on tesserae pattern and construc...
Educational Linkage Approach In Cultural Heritage   2.6.3. Layers and construction materials Mosaic floors Acropolis of At...
Educational Linkage Approach In Cultural Heritage   2.6.3. Layers and construction materials Wall Mosaics First layer:  Th...
Educational Linkage Approach In Cultural Heritage   2.6.4. Decay of Mosaics <ul><li>Decay factors </li></ul><ul><li>Humidi...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>All conservation interventions ...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>Photographic documentation </li...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>Surface conservation  (interven...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>Intervention down to the substr...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>Photographic documentation </li...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics <ul><li>Removal (or not) of the cut joi...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: M...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: M...
Educational Linkage Approach In Cultural Heritage   2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: M...
Educational Linkage Approach In Cultural Heritage   2.6.6.  Diagnostic Study  of Mosaics Prof. Antonia Moropoulou – Topic ...
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Elaich module 2 topic 2.6 - Historic materials of architectural surfaces: Mosaics

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Historic materials of architectural surfaces: Mosaics

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Elaich module 2 topic 2.6 - Historic materials of architectural surfaces: Mosaics

  1. 1. Educational Linkage Approach In Cultural Heritage Prof. Antonia Moropoulou - NTUA – National Technical University of Athens Knowing the built heritage Module 2 Basic Cour s e Teaching Material Topic 2 . 6 Introduction to the main historic decorative materials Mosaics Educational Toolkit
  2. 2. Prof. Antonia Moropoulou - NTUA – National Technical University of Athens Copyright ©ELAICH Beneficiaries 2009-2012 This material is an integral part of the “ELAICH – educational toolkit” and developed as part of the project ELAICH – Educational Linkage Approach in Cultural Heritage within the framework of EuroMed Cultural Heritage 4 Programme under grant agreement ENPI 150583. All rights reserved to the ELAICH Beneficiaries.   This material, in its entirety only, may be used in &quot;fair use&quot; only as part of the ELAICH – educational toolkit for the educational purposes by non-profit educational establishments or in self-education, by any means at all times and on any downloads, copies and or, adaptations, clearly indicating “©ELAICH Beneficiaries 2009-2011” and making reference to these terms.   Use of the material amounting to a distortion or mutilation of the material or is otherwise prejudicial to the honor or reputation of ELAICH Beneficiaries 2009-2011 is forbidden.   Use of parts of the material is strictly forbidden. No part of this material may be: (1) used other than intended (2) copied, reproduced or distributed in any physical or electronic form (3) reproduced in any publication of any kind (4) used as part of any other teaching material in any framework; unless prior written permission of the ELAICH Beneficiaries has been obtained. Disclaimer This document has been produced with the financial assistance of the European Union. The contents of this document are the sole responsibility of the ELAICH Consortium and can under no circumstances be regarded as reflecting the position of the European Union. Educational Linkage Approach In Cultural Heritage
  3. 3. Prof. Antonia Moropoulou - NTUA – National Technical University of Athens Abstract The current presentation examines one of the main historic decorative materials, the mosaics. Mosaics are architectural surfaces covered by a decorative layer consisting of tesserae (small pieces of colored glass, stone or other materials) that are attached to the surface by use of a mortar. Mosaics are subjected to various environmental factors, especially those exposed at the exterior of a building. The conservation of mosaics can vary in extent, from minimum to complete removal of the mosaic, conservation of the tesserae in lab, replacement of the bedding mortar and reattachment to the surface. The respective processes are demonstrated in the current presentation. Educational Linkage Approach In Cultural Heritage
  4. 4. Prof. Antonia Moropoulou - NTUA – National Technical University of Athens Content Educational Linkage Approach In Cultural Heritage Table of contents of this presentation 2.6 . 1 Definition of mosaics 2.6.2 Tesserae 2.6.3 Layers and construction materials 2.6.4 Decay of mosaics 2.6.5 Conservation of mosaics 2.6.6 Diagnostic study of mosaics
  5. 5. Educational Linkage Approach In Cultural Heritage 2.6.1. Definition of mosaics Prof. Antonia Moropoulou – Topic 2.6: Mosaics <ul><li>Tesserae can be made out of: </li></ul><ul><li>Natural materials (pebbles, marble, ivory, semiprecious stones, shells etc.) </li></ul><ul><li>Technical materials (fired clay, glass, enamel, gold, silver etc.) </li></ul>Hagia Sophia, Photo courtesy of A. Moropoulou Mosaic is defined as an architectural surface (wall, roof, floor) which is covered by a decorative layer consisting of tesserae (small pieces of colored glass, stone or other materials) that are attached to the surface by use of a mortar Reference : A. Moropoulou “Mosaics” Course Notes Course, Interdepartment Postgraduate Course Protection of Monuments, Sites and Complexes – Direction: Conservation Interventions - Techniques and Materials, National Technical University of Athens (2010)
  6. 6. Educational Linkage Approach In Cultural Heritage 2.6.2. Tesserae Type of mosaics based on tesserae pattern and construction Acropolis of Athens The laying down of the tesserae is known traditionally as the &quot;opus.&quot; Different opus result in a different flow or look of the piece Examples Opus tessellatum: Mosaic technique that involves the use of tesserae of uniform size applied to a ground to form pictures and ornamental designs. It was the most commonly used technique in the production of Hellenistic, Roman, early Christian, and Byzantine mosaics. The earliest mosaics in opus tessellatum were composed of stone and marble tesserae, but, in the course of the 2nd century, tesserae of coloured glass were introduced for special colour effects. In the Hellenistic period (3rd to 1st centuries bc) in cities in Greece, Africa, Sicily, and Italy, more commonly, opus tessellatum was reserved for decorative borders surrounding emblēmata, or central figural panels executed in opus vermiculatum, a finer mosaic work using much smaller tesserae. Beginning with the 1st century ad, however, figural opus tessellatum was increasingly used to cover whole floors, and by the early Christian period it had become the dominant technique. With the widespread use of monumental wall mosaics that began with that era, opus tessellatum entirely replaced opus vermiculatum, being much better suited, with its large tesserae and rougher visual effect, for viewing at a distance. Glass tesserae were used almost exclusively for these wall mosaics, and glass opus tessellatum remained the common mosaic technique throughout the Middle Ages. Opus vermiculatum : Type of mosaic work frequently used in Hellenistic and Roman times, in which part or all of a figural mosaic is made up of small, closely set tesserae (cubes of stone, ceramic, glass, or other hard material) that permit fine gradations of colour and an exact following of figure contours and outlines. The word vermiculatum (“wormlike”) refers to the undulating rows of tesserae that characterize this work. Opus vermiculatum was generally used for emblēmata, or central figural panels, which were surrounded by geometrical or floral designs in opus tessellatum, a coarser mosaic technique with larger tesserae; occasionally opus vermiculatum was used only for faces and other details in an opus tessellatum mosaic. Opus Alexandrinum : Type of decorative pavement work widely used in Byzantium in the 9th century. It utilized tiny, geometrically shaped pieces of coloured stone and glass paste that were arranged in intricate geometric patterns dotted with large disks of semiprecious stones Opus signinum : Type of simple, unpatterned or roughly patterned pavement commonly used in Roman times. It was composed of river gravel, small pieces of stone, or terra-cotta fragments cemented in lime or clay. Prof. Antonia Moropoulou – Topic 2.6: Mosaics Ibid
  7. 7. Educational Linkage Approach In Cultural Heritage 2.6.3. Layers and construction materials Mosaic floors Acropolis of Athens <ul><li>First layer: Stone structure or base structure, usually without a binder material, was placed on well wet, pressed and leveled ground. This structure, called statumen can consist of: </li></ul><ul><li>Natural pebbles, or stones, with their size increasing as art evolved </li></ul><ul><li>Ceramic fragments </li></ul><ul><li>Ceramic bricks </li></ul><ul><li>Curved ceramic tiles (Byzantine period) </li></ul><ul><li>Collection of various materials such as stones, ceramic bricks, fragments from marble sculpturing </li></ul><ul><li>Second layer: Called rudus , it was 5-15cm high and covered the statumen </li></ul><ul><li>Initially, the basic materials were river or sea sand that was properly washed, lime and gravel </li></ul><ul><li>Later or, earth of Thera was added, marble dust and during the roman period, brick dust. All materials were coarse </li></ul><ul><li>Third layer: Nucleus substrate , was layered carefully and at early years, it was used as the tesserae placement layer </li></ul><ul><li>The substrate usually consisted of the same materials as the previous layer (except gravel), but they were finer </li></ul><ul><li>Fourth layer: Supra nucleus , it was the finest of all layers and it was the one were the tesserae were laid </li></ul><ul><li>It was composed of the same materials as the nuclus, but contained less lime </li></ul>Mosaic, 6th c. Detail of the mosaic floor of a church in Thessaloniki (Museum of the Byzantine Culture, Thessaloniki Greece) Prof. Antonia Moropoulou – Topic 2.6: Mosaics Ibid
  8. 8. Educational Linkage Approach In Cultural Heritage 2.6.3. Layers and construction materials Wall Mosaics First layer: The layer in contact with the masonry consisted of lime, river sand, coarse crushed brick or tile, earth of Thera and straw Second layer: It consisted of lime, river sand, coarse crushed brick or tile, marble dust, earth of Thera, finer straw and albumen. Third layer: This was the tesserae positioning layer, and it consisted of lime at higher proportions than in the previous layers, river sand, marble dust, earth of Thera and albumen Detail of Empress Zoe, Christ & Emperor John II Mosaic, Hagia Sophia - South Gallery, Istanbul, (Photo courtesy of A. Moropoulou) Prof. Antonia Moropoulou – Topic 2.6: Mosaics Ibid
  9. 9. Educational Linkage Approach In Cultural Heritage 2.6.4. Decay of Mosaics <ul><li>Decay factors </li></ul><ul><li>Humidity is the main decay factor for mosaics as it imparts physical and chemical changes to the main components of the mosaics. It controls soluble salts decay and freeze-thaw decay </li></ul><ul><li>Atmospheric pollution . It is significant in external mosaics (floors, wall), and it is responsible for gypsum and crusts formation </li></ul><ul><li>Mechanical loads . Earthquakes, thermal expansion coefficient mismatches, wear from normal use </li></ul><ul><li>Biological factors . Flora, microorganisms etc, can result in the detachment of the tesserae from the substrate layers of the mosaic </li></ul>Detachment of Tesserae. Detail of Empress Zoe, Christ & Emperor John II Mosaic, Hagia Sophia - South Gallery, Istanbul, (Photo: A. Moropoulou) Prof. Antonia Moropoulou – Topic 2.6: Mosaics Ibid Cracks Tesserae detachment Substrate mortar failure Substrate detachment Crust formation on tesserae and joints
  10. 10. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>All conservation interventions must be thoroughly documented. Four options are available: </li></ul><ul><li>The mosaic remains in situ without any conservation and covered </li></ul><ul><li>The mosaic remains in situ without any conservation and not covered </li></ul><ul><li>The mosaic is detached in pieces and repositioned in situ on new substrate mortar </li></ul><ul><li>The mosaic is detached in pieces and placed in portable aluminum frames </li></ul><ul><li>Intervention approach. Three options are available: </li></ul><ul><li>Minimum intervention </li></ul><ul><li>Partial intervention </li></ul><ul><li>Complete intervention </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Ibid
  11. 11. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>Photographic documentation </li></ul><ul><li>Temporary consolidation of the edges of the mosaic with mortar </li></ul><ul><li>Consolidation of damaged areas, cleaning, cover the mosaic with polyethylane or polyester sheets </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Minimum Intervention <ul><li>Photographic documentation </li></ul><ul><li>Detailed drawing of the mosaic in 1:1 scale </li></ul><ul><li>Graphic documentation </li></ul><ul><li>Cleaning of encrustations and salt depositions (dry cleaning with brushes,mechanical cleaning, chemical cleaning, wet cleaning with steam or running water) </li></ul><ul><li>Consolidation of damaged areas with grouts (anchoring of the mosaic with pins and introduction of the grout to consolidate the mosaic) </li></ul><ul><li>Use of mortar to replace lost joints, consolidation of tesserae, removal of flora with proper herbicides </li></ul><ul><li>Aesthetic restoration, spraying biannually with herbicide to avoid flora development </li></ul><ul><li>Protection of the mosaic through construction of a shelter </li></ul>Partial Intervention Ibid
  12. 12. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>Surface conservation (intervention down to the tesserae deposition layer) </li></ul><ul><li>Restraint of the mosaic surface with wooden struts </li></ul><ul><li>Crust removal from the tesseae </li></ul><ul><li>Consolidation of loose tesserae </li></ul><ul><li>Aesthetic restoration of joints and lost areas </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Partial intervention - In situ conservation of a wall mosaic Ibid
  13. 13. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>Intervention down to the substrate </li></ul><ul><li>Graphic documentation of the mosaic in combination with photogrammetric documentation </li></ul><ul><li>Determination of the areas where grouts will be introduced </li></ul><ul><li>Removal of tesserae (after detailed documentation and numbering) to open holes </li></ul><ul><li>Grouts injection </li></ul><ul><li>Installation of pins (ceramic or plexiglass) to restrain mosaic areas </li></ul><ul><li>Reapplication of removed tesserae </li></ul><ul><li>Surface conservation </li></ul><ul><li>Aesthetic restoration </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Partial intervention - In situ conservation of a wall mosaic Ibid
  14. 14. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>Photographic documentation </li></ul><ul><li>Detailed drawing of the mosaic in 1:1 scale </li></ul><ul><li>Graphic documentation </li></ul><ul><li>Detachment, reapplication of new mortar </li></ul><ul><li>Crust removal and cleaning of the surfaces </li></ul><ul><li>Tesserae conservation, aesthetic restoration </li></ul><ul><li>Protection of the mosaic through construction of a shelter </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Complete Intervention Complete intervention - Mosaic detachment procedure <ul><li>Shelter protection of the work area </li></ul><ul><li>Photographic documentation of all interventions and actions </li></ul><ul><li>Scale drawing </li></ul><ul><li>Graphic documentation </li></ul><ul><li>Cleaning of the surface from all objects that could hinder good adhesion of the glue </li></ul><ul><li>Conservation of decayed tesserae </li></ul><ul><li>Numbering and plan drawing of the areas that will be removed and the way they will be cut </li></ul><ul><li>Protection of mortar edges with gauze </li></ul>Ibid
  15. 15. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics <ul><li>Removal (or not) of the cut joints </li></ul><ul><li>Application (gluing) of the first layer of cheese clothe </li></ul><ul><li>Application (if required) of a second layer of cheese clothe </li></ul><ul><li>Application of a cabot type fabric </li></ul><ul><li>Grid plan with the aid of thin metalbeams </li></ul><ul><li>Numbering of cut areas </li></ul><ul><li>Detachment </li></ul><ul><li>Laying on particle board (mortar side on board) </li></ul><ul><li>Cover with a second particle board on top of the tesserae </li></ul><ul><li>Flip over, removal of mortar side board </li></ul><ul><li>Removal of the historic mortar from the back side of the mosaic. In between the joints, there should remain minimum of the historic mortar, such as, when the mosaic is reattached on the surface, the front view will show the historic mortar </li></ul><ul><li>Preparation of the surface (wall, floor). Substrate construction </li></ul><ul><li>Reapplication on the new mortar of the numbered cut areas following the grid of the original mosaic. The preparation of the new mortar will be based on a characterization of the historic mortar regarding its composition, raw materials proportions, physicochemical characteristics, mechanical properties, and after taking into account the environmental impact on the mosaic </li></ul><ul><li>Removal of the cover clothes, and cleaning of the remaining glue </li></ul><ul><li>Reapplication of cut joints </li></ul>Prof. Antonia Moropoulou – Topic 2.6: Mosaics Complete Intervention – Mosaic detachment procedure (cont.) Ibid
  16. 16. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: Mosaics Laboratory conservation of mosaics <ul><li>1 st stage: Prior to conservation </li></ul><ul><li>Photographic documentation </li></ul><ul><li>Decay mapping (macroscopic observations) </li></ul>Detached mosaic part Ibid
  17. 17. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: Mosaics Laboratory conservation of mosaics <ul><li>2 nd stage: Conservation </li></ul><ul><li>Tesserae cleaning (typically mechanical) </li></ul><ul><li>Consolidation of loose tesserae </li></ul><ul><li>Aesthetic restoration of joints </li></ul>Ibid
  18. 18. Educational Linkage Approach In Cultural Heritage 2.6.5. Conservation of Mosaics Prof. Antonia Moropoulou – Topic 2.6: Mosaics Laboratory conservation of mosaics <ul><li>3 rd stage: After Conservation </li></ul><ul><li>Photographic documentation </li></ul>Ibid
  19. 19. Educational Linkage Approach In Cultural Heritage 2.6.6. Diagnostic Study of Mosaics Prof. Antonia Moropoulou – Topic 2.6: Mosaics See Module 2 – ADVANCED Diagnostic study of Hagia Sophia mosaics Prof. A. Moropoulou, NTUA For more information: Hagia Sophia mosaic – Upper South Gallery - Photo courtesy of A. Moropoulou ELAICH – Istanbul Experimental Course: Hagia Sophia - In situ use of Non Destructive Techniques to assess the decay state of mosaics and reveal the presence of plastered mosaics

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