Pamela Vandiver, University of Arizona
Weidong Li, Shanghai Institute of Ceramics, CAS
Philippe Sciau, Universite de Toulouse
Christopher Maines, National Gallery of Art
PP2: Pigment Analysis and Stability
Monday PM, December 02, 2013
Hynes, Level 3, Room 301
2:30 AM - *PP2.01
Analysis of Lead Carboxylates and Lead-Containing Pigments in Oil Paintings by Solid-State Nuclear Magnetic Resonance
Jaclyn Catalano 1 2 Yao Yao 2 Anna Murphy 2 Nicholas Zumbulyadis 3 Silvia Centeno 1 Cecil Dybowski 2
1Metropolitan Museum of Art New York USA2University of Delaware Newark USA3Independent Researcher Rochester USAShow Abstract
Soap formation in traditional oil paintings occurs when heavy metal-containing pigments, such as basic lead white, 2Pb(CO3)2.Pb(OH)2, and lead tin yellow type I, Pb2SnO4, react with fatty acids in the binding medium. These soaps may form aggregates that can be 100-200 mu;m in diameter, which swell and protrude through the paint surface, resulting in the degradation of the paint film and damage to the integrity of the artwork. In addition, soap formation has been reported to play a role in the increased transparency of paint films that allows the painting support, the preparatory drawing, and the artist's alterations to become visible to the naked eye. The factors that trigger soap formation and the mechanism/s of the process are not yet well understood. To elucidate these issues, chemical and structural information are necessary which can be obtained by solid-state 207Pb, 119Sn, and 13C nuclear magnetic resonance (NMR). In the present study, a combination of 207Pb NMR pulse sequences was used to determine accurately the NMR parameters of lead-containing pigments and lead carboxylates known to be involved in soap formation, such as lead palmitate, lead stearate, and lead azelate. These results show that the local coordination environment of lead azelate is different from lead palmitate or lead stearate. In addition, the chemical shifts of the pigments obtained are different from those of the soaps, demonstrating that 207Pb NMR is useful in characterizing the components when present in a mixture, such as a paint film. 119Sn NMR was also used to provide information on the coordination environment in lead tin yellow type I. Using this information, we have developed an NMR method to characterize laboratory-aged paint samples that showed soap formation by FTIR spectroscopy. The NMR methods discussed can also be applied to other Pb and Sn-containing cultural heritage materials, electronic and optoelectronic materials, superconducting materials, and environmentally contaminated materials.
3:00 AM - *PP2.02
Analysis and Replication of Jianyang Teabowls from Song Dynasty China
James Dustin Morehead 1 2
1University of Arizona Tucson USA2Ratheon Corp Tucson USAShow Abstract
Black-glazed tea bowls from Jianyang, Fujian province, China, were studied to further understand the visual appearance of the Jian teabowls. The black-glazed Jian bowls are segregated into two distinct visual appearances called “Hares Fur” and “Oil Spot”. These black glazes are alumino-silicates rich in calcium and iron oxides that through heat treatment form anorthite and various iron-oxide precipitates. Twenty-six teabowl sherds were analyzed from the collection of James Plumer who in 1935 first identified three of the Jianyang kilns. Data include electron microprobe analysis, scanning electron microscopy with energy dispersive X-ray analysis, X-ray diffraction, dilatometry and optical microscopy. Atomic and chemical compounds were determined, the melt temperature range was established, and glaze formulation and reproduction tests will be shown. These results provide further clues to unlocking the stunning but mysterious appearance of the Jianyang teabowls.
4:00 AM - *PP2.03
Discoloration of Prussian Blue Colored Papers : Effect of Light and Anoxia
Marie-Angelique Languille 1 Claire Gervais 2 Valerie Briois 3 Martine Gillet 4 Solenn Reguer 3 Edward Vicenzi 5 Loic Bertrand 3 1
1CNRS Gif-sur-Yvette France2Bern University of the Arts Bern Switzerland3Synchrotron SOLEIL Gif-sur-Yvette France4CNRS Paris France5Smithsonian Institution Museum Conservation Institute Suitland USAShow Abstract
Prussian blue (PB, hydrated iron(III) hexacyanoferrate(II)), which is nowadays widely studied for its intriguing magnetic and optical properties, was first of all a pigment used in artworks, since its discovery in 1704. PB is found in many different artworks in Europe from the 18th and 19th centuries, especially in paintings, watercolours and photographs. It is sensitive to light and anoxia in such a way that a loss of colour of the pigment may occur, leading to visible damages in artefacts made of PB. For this reason, understanding of the PB fading is a key issue in conservation science that meets with solid state physics current research on properties and functionality of mixed valency compounds. Part of our work is to understand the alteration of the pigment as a function its interaction with the substrate and on the environmental conditions (RH, T, luminosity). We do it through the investigation of model-samples: coloured papers prepared by immersion in a PB colloidal suspension, and cyanotypes that are photographic prints.
I will start by describing the synthesis and the elemental / structural characterization of the PB powder and the PB papers and cyanotypes by SEM, XRD and Raman spectroscopy. I will then present colorimetric measurements on those PB papers and cyanotypes before and after artificial fading treatments in O2/N2/RH controlled atmospheres. I will show the effects of the type of synthesis, the kind of papers, and the PB concentration in the coloured papers. In this way, the role of the interaction of the pigment with the substrate in the discoloration will be pointed out.
Finally, I will present Fe K-edge spectroscopy measurements that we employed to study the Fe chemical local environment of the same PB model samples. In these experiments, we used the X-ray beam as a source of fading, in presence or not of an additional UV-visible light. Post-edge region in the XAS spectra revealed changes of the PB structure as a function of the substrate and time-resolved XAS measurements (quick-XAS and dispersive XAS) allowed to follow the kinetics of the reduction of iron(III) into iron (II).
In summary, our results suggest that the structure of PB and its variation are related to the substrate, which definitely contribute to the various fading behaviors observed. From a conservation point of view, knowledge about the physico-chemical process of PB fading could substantially help to improve the conservation of PB artefacts, as techniques to prevent pigment from fading or substrate from ageing can vary substantially.
4:30 AM - *PP2.04
Characterization and Identification of van Dyke Brown, Asphalt, Bistre and Sepia Pigments in Works of Art by SERS, GC-MS, FTIR and XRF.
Maria Lorena Roldan 1 Silvia A. Centeno 1 Adriana Rizzo 1 Yana van Dyke 2
1The Metropolitan Museum of Art New York USA2The Metropolitan Museum of Art New York USAShow Abstract
The black-brown pigments van Dyke brown, asphalt, bistre and sepia have been used in works of art for centuries. The use of van Dyke brown and its ‘homologues&’ Kassel earth and Cologne earth has been reported in paintings dating to the sixteenth and seventeenth centuries. Although asphalt has been used since antiquity for various purposes, it attained use as a pigment in the sixteenth and seventeenth centuries, and by the eighteenth century, it was in routine use in oil painting, ground in turpentine, particularly for glazing, shading and specifically for flesh shadows. Bistre was mentioned in documentary sources in the seventeenth century and was used primarily in watercolor, since asphalt supplied the needs for oil painting. Sepia was essentially used for writing purposes and became popular in late eighteenth century when partially displaced Indian ink and bistre [1-3].
These black brown pigments are among the most difficult to identify in works of art due to their complex nature and many possible origins. Some of these pigments also present challenges to conservators due to the fact that they may induce cracking, wrinkling, exfoliation, fading, and darkening of the paint layers they compose. Conventional analytical methods frequently used for identifying them in works of art generally fail due to their heterogeneous nature.
The goal of the present work was to develop an analytical strategy to firmly identify these pigments in works of art. For this purpose, a combination of different analytical techniques, including FTIR, SERS combined with PCA analysis, XRF and GC-MS, was employed to characterize a set of 25 commercial pigment samples of different origins. The optimized methodology was successfully applied to identify black brown pigments in microsamples taken from paintings and other objects in the collection of The Metropolitan Museum of Art.
 Berrie, B. H. Artists&’ Pigments, A Handbook of Their History and Characteristics, vol. 4, Archetype Publications, London, 2007.
 Eastaugh N., Walsh V., Chaplin, T., Siddall, R., Pigment Compendium. A Dictionary of Historical Pigments, Elsevier Butterworth-Heinemann, Amsterdam, 2004.
 Languri, G. M. Molecular studies of asphalt, mummy and Kassel earth pigments: their characterization, identification and effect on the drying of traditional oil paint. PhD Thesis, University of Amsterdam, 2004.
Keywords: van Dyke brown, bistre, asphalt, bitumen, sepia, SERS, PCA, GC-MS, FTIR, XRF
5:00 AM - *PP2.05
Study of Mexican Colonial Mural Paintings: An In situ Non-Invasive Approach
Jose Luis Ruvalcaba Sil 1 Malinalli Wong Rueda 1 Maria Angelica Garcia Bucio 1 Edgar Casanova Gonzalez 1 Mayra Manrique Ortega 1 Valentina Aguilar Melo 1 Pieterjan Claes 1 Dulce Maria Aguilar Tellez 1
1Instituto de Fisica, Universidad Nacional Autonoma de Mexico Mexico MexicoShow Abstract
The main objective of this work lays in the study of the pigments and other components of the mural paintings of three colonial Augustinian convents. All of them are located in the state of Hidalgo in Mexico. The first one is the ex-convent of San Andrés Apostol in Epazoyucan, the second is San Nicolas Tolentino in Actopan and the third ex-convent is the one of San Miguel Arcangel, located in Ixmiquilpan. These places have been selected because of the inherent characteristics of the paintings, which can be dated back to the XVI and XVII century. Before this research, there was little information on the materials and pictorial techniques used to paint these works.
Our MOVIL project is equipped with the necessary instruments to pursue an in situ study directly on the mural paintings. Here, we present X-Ray Fluorescence, Raman and Infrared (FT-IR) spectroscopic results using portable devices conducted on nine paintings in these convents.
From these results, we were able to compare between the mural paintings of these three sites and distinguish between different pigments used for the diverse colors, such as vermillion, orpiment, and copper resin for the bright red, gold yellow, and green, respectively. These pigments are characteristic for the known novo-Hispanic color palette. Apart from this, we also found the presence of indigo in the blues, minium, and cochinilla. Furthermore, during this study silver nanoparticles were used to carry out Surface Enhanced Raman Spectroscopy (SERS) measurements directly on the paintings, for the first time in Mexico. This research has shown that the painting techniques of these convents are different and the art historian&’s hypothesis regarding an itinerant group of painters cannot be longer supported.
This study was supported by the project PAPIIT IN401710 UNAM, as well as the CONACyT 131944 MOVIL, PAPIIT UNAM IN402813 ANDREAH II and ICyTDF PICCO10-57 grants.
5:30 AM - *PP2.06
The Materials Used for Painting in Teotihuacan
Xim Bokhimi 1 Linda R. Manzanilla 2 Antonio Morales 1
1Universidad Nacional Autonoma de Mexico Mexico City Mexico2Universidad Nacional Autonoma de Mexico Mexico City MexicoShow Abstract
Teotihuacan was a megalopolis during the third to the sixth centuries AD, where one of the dominant cultures in Central Mexico settled. About 1500 years ago, the city was destroyed, and converted in an archeological site. Their habitants developed a high level culture in all aspects, one of which was the technology for painting. The city was decorated everywhere, and Teotihuacan people developed and prepared a large amount of different kinds of materials to decorate the city and polychrome pottery. In this paper we present a characterization of the different materials used for painting, which were found during the excavation by Linda R. Manzanilla (from 1997 to 2012) of two sites associated from Teotihuacan: Teopancazco, a multiethnic neighborhood center in the southeastern sector of the city, and Xalla, a palatial complex perhaps related to the ruling elite. Materials characterization was made using X-ray powder diffraction, electron backscattering diffraction, refinement of the crystalline structures, and scanning electron microscopy. Through these techniques, it was possible to find and characterize the different minerals used to prepare the pigments and their supports. We also tried to find information about the techniques used to prepare and apply these paintings, and the sites in Mexico from where these minerals were extracted. By refining the different phases found in the archeological samples, it was possible to get their concentrations and fine details about their crystallography.
Monday AM, December 02, 2013
Hynes, Level 3, Room 301
10:00 AM - *PP1.01
Evaluation of Bronze Casting Technology Using Neutron Radiography, Tomography, and Diffraction
Susan N. Herringer 1 2 3 Hassina Z. Bilheux 2 Ke An 2 Krysta Ryzewski 4 Brian W. Sheldon 1
1Brown University Providence USA2Oak Ridge National Laboratory Oak Ridge USA3Brown University Providence USA4Wayne State University Detroit USAShow Abstract
A number of methods have been used to study the fabrication techniques of archaeometallurgical objects - such as metallography and X-ray radiography/tomography. However, these methods can be invasive and destructive (as is the case for metallography) or, in the case of X-rays, may not be able to reveal as much detail due to limitations in penetration depth. Neutron imaging, on the other hand, provides a non-invasive and non-destructive means of probing metallic cultural heritage objects. In addition, neutrons are able to penetrate metals to a greater depth than X-rays thereby providing greater detail to internal structure. The application of neutron methods to cultural heritage materials is a growing field of research, especially abroad. Neutron imaging have recently been used to explore a number of bronze archaeological materials on the CG-1D prototype neutron imaging beamline at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory in Oak Ridge, TN. The results of these studies have revealed otherwise inaccessible information about the structure and manufacturing processes of archaeomaterials, which has pressed for further examination utilizing neutron diffraction. The focus of this presentation will be the investigation of casting techniques of solid cast bronzes using neutron imaging and diffraction. The talk will detail the analysis of a Roman bronze dog figurine from the Joukowsky Institute for Archaeology and the Ancient World as well as a comparative analysis to experimental cast bronzes. The analysis will include an evaluation of the materials on the basis of variation in alloy composition within the bronze.
10:30 AM - *PP1.02
The Use of Synchrotron Radiation in Archaeometallurgy
Marcus Young 1
1University of North Texas Denton USAShow Abstract
Archaeometallurgy, the study of ancient metal artifacts, provides valuable insight into the ancient cultures that produced them. Scientific investigation of these artifacts can answer many questions pertaining to, for example, provenance and trade, manufacturing and fabrication technologies, corrosion processes and conservation treatments, and authenticity and dating. Since many of these artifacts are unique and irreplaceable, the ability to examine these artifacts non-destructively is paramount to the application of a particular analytical technique and the success of these studies. Synchrotron radiation (SR) is an important and powerful analytical tool, offering many unique non-destructive techniques, in the field of archaeometallurgy. In this presentation, the characteristics and capabilities of current and future SR facilities, as well as specific SR techniques, will be discussed. SR techniques such as x-ray imaging (radiography/microscopy and tomography), x-ray diffraction, x-ray fluorescence, x-ray spectroscopy, Fourier transform infrared spectroscopy, and lastly combined SR techniques to the field of archaeometallurgy will be presented, compared, and contrasted. Individual case studies will be presented to illustrate the relevant SR technique. Lastly, a brief explanation of deciding when to use an SR technique and how to obtain beam time will be addressed.
11:30 AM - *PP1.03
Investigating a Moche Cast Copper Artifact for Its Manufacturing Technology
Aaron Shugar 1 Michael Notis 4 Dale Newbury 2 Nicholas Ritchie 3
1Buffalo State Collage Buffalo USA2National Institute of Standards and Technology Gaithersburg USA3National Institute of Standards and Technology Gaithersburg USA4Lehigh University Bethlehem USAShow Abstract
A Moche cast copper alloy object was investigated with focus in three main areas: the alloy composition, the casting technology, and the corrosion process. This complex artifact has thin connective arms between the body and the head, a situation that would be very difficult to cast. The entire artifact was mounted and polished allowing for a complete microstructural and microchemical analysis, providing insight into the forming technology. In addition gigapixel x-ray spectrum imaging was undertaken to explore the alloy composition and the solidification process across the entire sample. This process used four 30 mm2 SDD-EDS detectors to collect the 150 gigabyte file mapping an area of 46080 x 39934 pixels. Raman analysis was performed to confirm the corrosion compounds.
12:00 PM - PP1.04
Benefits of the Complementary Use of Archaeometry Investigations and Historical Research in the Study of Ancient Airplanes: The Example of Breguet Sahararsquo;s Rivets
Audrey Cochard 1 Joel Douin 1 Benedicte Warot-Fonrose 1 Julitte Huez 2 Luc Robbiola 3 Jean-Marc Olivier 4 Philippe Sciau 1
1CEMES-CNRS Toulouse France2CIRIMAT-ENSIACET-INPT Toulouse France3TRACES-CNRS Toulouse France4FRAMESPA-UTM Toulouse FranceShow Abstract
In the field of cultural heritage, chemical and structural information concerning Al-alloys used in aeronautic industry is more and more required. These data are useful not only in the field of history of sciences and techniques, but also to understand the corrosion mechanisms, which is a curse for air and space museums.
In the present work, we want to show how to obtain precise information on a Al alloy using a physicochemical and an historical approach. Although these materials were processed less than a century ago in an industrial context, it is not so easy to find pertinent chemical and physical data. For example, the main Al-alloys used by the aeronautic industry after World War II are mentioned in various vintage technical reviews but without direct links with airplanes made at the same period. This indirect information could be very useful to interpret the results of laboratory investigations.
To illustrate all the interest to perform this double approach, we present the results obtained in the study of some Al-Alloys used in the manufacturing of the Breguet 765 Sahara, which is presently in restoration by the Toulouse association “les ailes anciennes”. The first flight of freighter version (Br. 765) for the French Air Force was in 1958. It is the last version of the family of French double-deck transport aircraft produced by Breguet between 1948 and 1960. In the midpoints of fifty years a new Al-alloy was developed for rivets, which is a key element of airplane structure. We have found papers of fifty years, which present and discuss the nature and the properties of this new alloy whereas laboratory investigations have revealed that it was used in the Br. 765 for some rivets applied for strengthening
The results of chemical and structural study at different scale (from nanometre to centimetre) will be presented in relation with the information found in in the literature of the period. For the confrontation between the two data sources, we will try to precise the nature, the heat treatment and the mechanical properties as well as to deduce information on the time evolution (aging).of these Al-alloys.
12:15 PM - PP1.05
Characterization of a Surface Tarnish Found on Daguerreotypes under Shortwave Ultraviolet Radiation
Aaron Shugar 1 Krista Lough 1 Jiuan-Jiuan Chen 1
1Buffalo State Collage Buffalo USAShow Abstract
A characteristic fluorescent tarnish can be observed on some daguerreotypes under shortwave ultraviolet radiation. The fluorescence can be seen in several distinct patterns: edge tarnish, rings, and continuous films. Dispersive Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were applied to characterize and identify the fluorescent compound. Raman spectroscopy identified the characteristic peak for copper cyanide, CuCN, at 2172 cm-1. Elemental k-ratio maps of the SEM analysis indicated an increase in copper, carbon and nitrogen in the area of fluorescence. Powder XRD was to confirm the identification of a copper cyanide compound. Shortwave ultraviolet radiation can be used in a monitoring program of daguerreotypes to further characterize the fluorescent tarnish and its affect on the deterioration of daguerreotypes.
Pamela Vandiver, University of Arizona
Weidong Li, Shanghai Institute of Ceramics, CAS
Philippe Sciau, Universite de Toulouse
Christopher Maines, National Gallery of Art
PP4: Organic Materials Properties
Tuesday PM, December 03, 2013
Hynes, Level 3, Room 301
3:00 AM - *PP4.01
Hawaiian Barkcloth from the Bishop Museum Collections: A Characterization of Materials and Techniques in Collaboration with Modern Practitioners to Effect Preservation of a Traditional Cultural Practice
Christina Bisulca 1 2 Lisa Schattenburg-Raymond 2 Kamalu du Preez 2
1University of Arizona Tucson USA2Bernice Pauahi Bishop Museum Honolulu USAShow Abstract
Hawaiian barkcloth (kapa) is a traditional fabric made from beaten plant fibers. Because of its function in both utilitarian and chiefly ornaments, kapa is intimately tied to the history and traditions of Hawai&’i. In the 19th century kapa was gradually replaced with imported textiles and the practice was lost. The traditional methods used to manufacture kapa are now only known from historic descriptions by early missionaries and explorers. Since the 1970s, cultural practitioners began an effort to revive this artform and are experimenting with materials and techniques to reproduce kapa with the quality of historic artifacts.
New research has been undertaken at the Bishop Museum using a multi-analytical approach to determine the colorants used in kapa. The Bishop Museum holds the world&’s best collection of kapa, including some of the earliest pieces collected from Cook&’s voyage in the 18th century. The research has focused on a comprehensive survey of over 150 pieces of kapa with x-ray fluorescence spectroscopy (XRF). In some cases, samples were removed and analyzed with scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and chromatographic techniques, including high performance liquid chromatography (HPLC). Scientific results document the use of traditional pigments and dyes as well as the incorporation of imported materials in the 19th century. Results are interpreted by period, design and use, as well as within the context of historic descriptions. An important aspect of this work is close collaboration with cultural practitioners experienced fabrication methods that have been successful in the recreation of kapa. With continued research, the goal is to ultimately gain a greater knowledge of historic materials and techniques for the continuation of this important tradition.
PP5: Conservation Practices
Tuesday PM, December 03, 2013
Hynes, Level 3, Room 301
4:00 AM - *PP5.01
Dispersions of Surface Modified Calcium Hydroxide Nanoparticles with Enhanced Kinetic Stability: Properties and Applications to Desalination and Consolidation of the Yungang Grottoes
Ya Xiao 1 2 Feng Gao 1 3 Yun Fang 4 Youdan Tan 1 5 Kaiyu Liu 5 Shaojun Liu 1 5
1Central South University Changsha China2Cultural Relics and Archaeology Institute of Hunan Province Changsha China3Chinese Academy of Cultural Heritage Beijing China4China University of Geosciences (Wuhan) Wuhan China5Central South University Changsha ChinaShow Abstract
Calcium hydroxide is one of the most interesting materials to perform consolidation of stone sculptures, monuments, mortars or wall paintings. In this study, we reported on the synthesis and characterization of dispersions of surface modified calcium hydroxide nanoparticles with enhanced kinetic stability and their applications to conservation of the Yungang grottoes. Uniform hexagonal calcium hydroxide nanoparticles (~35nm) were obtained by mixing NaOH and CaCl2 aqueous solutions at 100~175oC using homogeneous-phase reactions, as characterized by X-rays diffractometer, scanning electron microscopy, and fourier transform infrared spectroscopy. It was further demonstrated that KH-570 surfactant agent can significantly reduce agglomeration and improve specific surface area of as-synthesized calcium hydroxide nanoparticles. Brunauer-Emmett-Teller (BET) measurement showed that specific surface area of modified calcium hydroxide nanoparticles reached up to ~48.78m2/g, about 2.5 and 3.4 times higher than that of unmodified and commercial ones, respectively. The kinetic stability of calcium hydroxide despersions can be further enhanced accompanying with decrease of the viscosity by optimizing the ratio of ethanol and n-propanol mixture. Especially, an innovative technique, which combined with the Ferroni-Dini method and dispersions of calcium hydroxide nanoparticles with enhanced kinetic stability, was proposed to effectively desalinate and consolidate the weathered stone, as evidenced by significant decrease of the porosity and concentration of detrimental Cl- and SO42- ions in the severely weathered stone samples from the Yungang grottoes, which was shown by nuclear magnetic resonance and ion chromatograph measurement, respectively. With good compatibility and weatherability, this technique described herein shows promising applications in stone or mortars heritage conservation.
4:30 AM - *PP5.02
Environmental Monitoring of VOCs Using Silica Gel, Zeolites and Activated Charcoal
Molly McGath 1 Blythe McCarthy 1 Jenifer Bosworth 1
1Freer|Sackler, Smithsonian Institution Washington USAShow Abstract
Volatile organic compounds (VOCs) like naphthalene, camphor, acetic acid and others can be hazardous to human health and can negatively impact the long-term stability of art objects. Silica gel, zeolites and activated charcoal are often placed in proximity to art objects as humidity regulators or air filtering agents and these materials adsorb VOCs to varying degrees. This research uses a Frontier 2020iD pyrolyzer coupled to a Shimadzu gas chromatographer/mass spectrometer (GC/MS) to evaluate the adsorbing power of silica gel, zeolites and activated charcoal in comparison with solid-phase micro-extraction (SPME) fibers. It shows that in addition to their primary roles as either a humidity regulators or filters: silica gel, zeolites and activated charcoal can serve as environmental monitoring agents of VOCs.
5:00 AM - PP5.03
Thermally Re-Workable Epoxy Adhesives for Use in Reconstructing Artifacts
Elyse M. Canosa 1 Stephen M. Budy 1 Douglas A. Loy 1 2 Pamela Vandiver 1 Nancy Odegaard 1 3
1University of Arizona Tucson USA2University of Arizona Tucson USA3University of Arizona Tucson USAShow Abstract
Polymeric adhesives such as acrylics and epoxies are commonly used for the reconstruction and repair of ceramic and glass artifacts. Currently used epoxies are non-reversible after they have cured, making any important structural artifact corrections impossible. We have therefore tailored an epoxy which is thermally reversible from solid to liquid state so that it is beneficial as a new application to the conservation community. The purpose of this project is to study the chemical, mechanical, and working properties of such an epoxy specifically in relation to its use on artifacts. Because of the superior strength of epoxy adhesives, our approach was to incorporate thermal Diels-Alder weak-links into epoxy resin. We synthesized an adhesive that behaves like a typical epoxy but also has the property of thermal reversibility. This allows conversion of the solid epoxy into liquid and back again, providing the potential for re-workability and removal if necessary. The epoxy was fully characterized via NMR, ATR-FTIR spectroscopy, HR-MS spectroscopy, TGA, and MDSC analysis, and the curing properties optimized using four commercial hardeners. All ceramic substrates were characterized prior to epoxy application using xeroradiography, SEM, water contact angle analysis, and boiling water analysis (ASTM C20-00, 2010) to understand porosity, pore distribution, and wetting abilities. We investigated the practical properties of these thermally re-workable epoxy adhesives for use on glass and ceramic artifacts by applying and reversing cured epoxy material. Through such tests we were able to show that these adhesives can be re-worked even after a cure time of more than 24 hours.
5:15 AM - PP5.04
Effects of Humidity on Gessoes for Easel Paintings
Michael Doutre 1 Alison Murray 1 Laura Fuster-Lopez 2
1Queen's University Kingston Canada2Universidad Politecnica de Valencia Valencia SpainShow Abstract
The filling of areas of loss is an important aspect in the conservation treatment of paintings. Losses from the image plane alter the work of art, distracting the viewer and making the image less representative of the original intent of the artist. To avoid deforming and damaging a work, it is important to understand and identify where and how the forces are distributed amongst the various layers of a painting. Also, any materials applied during conservation must not contribute additional stresses. This paper reports on the experimental results from an investigation into the effects of relative humidity on a variety of commercial and lab-prepared gessoes. Gessoes are widely used in easel painting as grounds; in art conservation, gessoes are used as infill materials to level a loss in the paint surface in preparation for inpainting. The primary focus of this investigation was to establish the mechanical behaviour of these materials with various relative humidities and offer a direct comparison between the modern commercial products and traditional hide glue and calcium carbonate gesso. Uniaxial tensile testing was performed at a range of relative humidities to characterize the elastic modulus and ultimate tensile strength (UTS) of the materials, soon after preparation and after artificial aging.
PP3: Methods of Analysis for Culture Heritage
Tuesday AM, December 03, 2013
Hynes, Level 3, Room 301
9:30 AM - *PP3.01
Preliminary Study of Architectural Cloisonne Enamel from Fuwangge in the Forbidden City
Hongying Duan 1 Liang Qu 1 Shiwei Wang 2 Pamela Vandiver 3
1Conservation Department of the Palace Museum Beijing China2Architecture Department of the Palace Museum Beijing China3University of Arizona Tucson USAShow Abstract
Fuwangge, located in the forth courtyard of Ningshougong Garden (Qianlong Garden), was built in the 36th reign year of Qianlong and employed a wide variety of decorative craftsmanship, including woodcarving, bamboo filament, lacquer carving, Cloisonne enamel, copper chisel, jade carving, mother-of-pearl inlay, embroidery, painting and calligraphy mounting among other crafts, that represented the highest standard of practices during the Qianlong emperior's reign (1736-1795A.D.) in Qing Dynasty. Wooden decoration on the ground floor of Fuwangge had inlayed many Cloisonne enamel components. According to literature and research, these enamel components were made by Yangzhou artisans, sometime after Cloisonne enameling technology that originated in Europe and was transferred to China. In emperor Qianlong's reign, Cloisonne enamels were deeply appreciated by the emperor and widely used in royal artifacts, objects of daily use and building decorations.
To study raw materials and manufacturing technology of Cloisonne enamel and to provide scientific evidence for copies and supplementary work on enamel components, Cloisonne enamel from Fuwangge was analyzed in this work. Through on-site investigation of Cloisonne enamel components in Fuwangge, three representative groups of samples were chosen. Among these, two contain eight kinds colored enamel glaze. After comparison of several methods, LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) was used as a micro-destructive analysis method and is suggested to be the most suitable method for glaze chemical composition measurement. We apply LA-ICP-MS method in-situ to determine eight kinds color enamel glaze and obtain major, minor and trace elemental quantitative analyses for the reign year of emperor Qianlong reign that is 1771 A.D. Two samples were also analyzed by Raman spectrometry. According to chemical composition and Raman signatures, glaze matrix, pigments and opacifier are discussed. The results indicate that enamel glaze matrix is potassium-calcium-lead glass (K-Ca-Si-Pb) also containing sodium (Na), boron (B) and fluorine (F). Pigment of yellow glaze is lead-tin yellow, and gold (Au) is the colorant element in pink enamel glaze. Combining analyses with literary records, conclusions are made about raw materials and manufacture technology.
10:00 AM - *PP3.02
Dual Beam Scanning Electron Microscope (SEM) and Focused Ion Beam (FIB): A Novel Method for Characterization of Cultural Heritage Objects
Matthew Aaron Carl 1 Chris A. Smith 1 Marcus L. Young 1 Kevin Tucker 2 Mark Leonard 2 John Dennis 2
1University of North Texas Denton USA2Dallas Museum of Art Dallas USAShow Abstract
Knowledge of the composition of modern American Ag and Ag-plated cultural heritage objects is limited, resulting in many unanswered questions in regards to the provenance, composition, and production methods. In this paper, the author&’s objective is to determine the bulk metal and, when present, plating compositions of Ag and Ag-plated objects of importance to the Dallas Museum of Art (DMA). One of the major challenges with studying ancient and modern cultural heritage and art objects is that they must be non-destructively and non-invasively examined, which often requires a combination of analytical techniques for full characterization. Analytical techniques such as conventional X-ray diffraction and X-ray fluorescence allow for surface studies of the objects, but cannot examine the bulk material; furthermore, these surface studies can be misleading since many objects have alterations on the surface such as corrosion layers, tarnishes, patinas, plating, and post-excavation cleaning. While studies on the bulk material can be performed non-destructively using synchrotron, neutron, and proton sources only available at large user facilities, only a few select objects can be examined at one time due to the nature of these facilities.
By using a FEI Nova 200 Nanolabs dual beam ultra-high resolution field emission scanning electron microscopy (SEM) / focused ion beam (FIB) with energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD), it is possible to examine a large number of objects quickly and efficiently. In this presentation, we show, for the first time, that this novel FIB technique can be successfully applied non-destructively to cultural heritage objects by examining three representative Ag-plated objects (a Candelabra, “Century” spoon, and New York World&’s Fair spoon) from the DMA&’s unparalleled collection of Modern American Silver. In each case, we successfully reveal and characterize the bulk metal as well as the Ag-plating, up to ~50 µm thick and show that there is no significant visual damage resulting from the milling process of the FIB. It can easily be foreseen that this novel characterization technique can be applied, due to its ease of availability and rapid use, in a much broader scope rather than just Ag-plated objects, making FIB a cornerstone technique in the field.
10:30 AM - *PP3.03
The Potential of Low Frequency EPR Spectroscopy in Studying Pottery Artifacts
Joseph P. Hornak 1 2 William J. Ryan 2 Nicholas Zumbulyadis 3
1RIT Rochester USA2RIT Rochester USA3Independent Researcher Rochester USAShow Abstract
Non-destructive authentication of ceramic and porcelain cultural artifacts is a challenging problem for the sciences. Electron paramagnetic resonance (EPR) spectroscopy is capable of distinguishing between clays based on the paramagnetic metals present, and firing temperature based on the complexes of these metals formed at different firing temperatures. Unfortunately, the 9 GHz frequency of conventional EPR restricts sample size to a few mm and limits its applicability to small fragments. Low frequency EPR (LFEPR), as the name implies, is an EPR operating at a few hundred MHz. LFEPR can utilize larger samples on the order of a few cm3, but has a lower sensitivity due to the smaller Boltzmann ratio. Additionally, LFEPR may not be capable of detecting a spectral transition if the LFEPR operating frequency is less then the zero field splitting of the paramagnetic metal complex. We utilized a LFEPR operating at 250 MHz which scans the applied magnetic field between the local Earth&’s magnetic field and 26 mT to determine the feasibility of detecting the EPR signal from clay samples. Various terracotta clay samples were studied at firing temperatures between 100 and 1200 °C. Spectral differences were seen as a function of both clay type and firing temperature. The characteristic transitions at g = 4 and 2 for iron complexes were seen with sufficient clarity to justify the use of LFEPR for studies of ceramic artifacts and potentially enamels on porcelain objects and glass. We have also explored the utility of LFEPR by the use of a surface coil rather than an enclosed resonator. Although the active volume of the surface coil is ~1 cm3, objects as large as 20 cm in diameter might be easily characterized with our spectrometer. Likely advances in magnet technology may enable the non-destructive examination of even larger pieces.
11:30 AM - PP3.04
Weaving in the Dark: SEM and EDX Analysis of Ancient Stone Tools from the Late Neolithic Period in Jordan
Kathleen Bennallack 1 Samantha Stout 1
1University of California, San Diego San Diego USAShow Abstract
Ancient stone tools (“lithics”) are usually categorized by their apparent function and then studied as though this categorization were fact, but actually knowing their function in the past is unreliable at best. Educated guesses are usually made on the basis of ethnographic parallels and use-wear experiments with modern versions of ancient tools (e.g. butchering a cow with replica stone knives), but with scanning electron microscopy (SEM) we can get a more accurate estimate of how stone tools were really used in the past. The SEM provides a highly focused, detailed image of the topographical features on the use-wear surface, and the energy dispersive x-ray (EDX) probe can provide a chemical spectrum of the surface layer for potential residue analysis. Using both topographical and residue analysis, we hope to determine what materials tools were used on; discovering whether they worked bone, hide, siliceous plants, meat, textile, or various other materials is highly informative and often surprising. In the 1980s this method went through a boom period, but is used much more rarely these days. We propose to examine an assemblage of tools from a newly excavated processing complex of undetermined type (possibly weaving), dating from the Late Neolithic period (c. 8250-7300BP) in Southern Jordan. The Late Neolithic period is less studied than many others in the region and is often thought of as a “dark age.” However, scholarship on this period has accelerated very recently as new sites have proved to be more numerous and complex than previously thought, and this study is a step toward joining the community working on the Late Neolithic as excavation and publication gain momentum.
11:45 AM - *PP3.05
Non-Invasive Characterization of Stone Artifacts from Templo Mayor of Tenochtitlan, Mexico
Mayra Dafne Manrique Ortega 1 Valentina Aguilar Melo 1 Emiliano Melgar Tisoc 2 Malinalli Wong Rueda 1 Edgar Casanova Gonzalez 1 Pieterjan Claes 1 Jose Luis Ruvalcaba Sil 1
1Universidad Nacional Autamp;#243;noma de Mamp;#233;xico Mexico City Mexico2Instituto Nacional de Antropologamp;#237;a e Historia Mexico City MexicoShow Abstract
The Templo Mayor of Tenochtitlan Museum in Mexico City holds a collection of thousands of polished stone pieces which are related to different offerings corresponding to various construction stages (II-VII) of the ceremonial area of the Aztec capital from the foundation of the city in 1325 up to 1521, when the city was conquered by the Spaniards.
The investigation of the elemental and chemical composition of these archaeological artifacts helps us to understand the provenance of pieces, the use of mineral sources, and trade routes, related to the development of the Aztec empire.
In the last year, a full analysis on stone artifacts using portable Raman, Infrared spectroscopy (FTIR) and X-ray fluorescence (XRF) was carried out on several hundred pieces in order to obtain a general overview of the variety of minerals present in the collection, as well as the corresponding groups of elemental composition that can be related to mineral sources. Moreover, these data can be chronologically associated to the construction stages. In this work the analytical methodology and main results are presented.
This research has been supported by grants from CONACyT 131944 MOVIL, PAPIIT IN402813 ANDREAH II and ICyTDF PICCO10-57.
12:15 PM - PP3.06
Use of Flexible Electrodes as Diagnostic Tools to Protect Artwork
Alice Heller England 1 Tami Lasseter Clare 1
1Portland State University Portland USAShow Abstract
A novel conductive hydrogel was synthesized for use as a flexible electrode material in electrochemical impedance spectroscopy (EIS) characterization of the barrier properties of protective coatings on outdoor metal works, such as bronze sculptures. The hydrogel is a copolymer of 2-acrylamido-1-propanesulfonic acid (AMPS) and poly(acrylic acid) (PAA), similar to gels used in many medical applications. The hydrogel was soaked in different electrolyte solutions and characterized by FT-IR spectroscopy, swelling capacity, conductivity, and impedance in both equilibrium and short time soaking conditions. Electrolytes of various cations and anions were investigated, and the results are interpreted based on the interactions of the ions with both the water and the fixed charges (-SO3-, -CO3-) in the hydrogel network. For optimal electrode performance, the soaked gels that exhibited higher conductivity while maintaining a moderate swelling ratio were selected to use in the development of the EIS diagnostic cell for monitoring coated metal substrates. For coatings on cultural heritage objects, additional precautions must be taken to ensure the underlying object remains unchanged during the measurement. Therefore the most suitable electrolytes for the gel electrodes are restricted to those at near neutral pH and with ions that are less likely to contribute to or induce corrosion on the substrate.
Because the hydrogels exhibit their own characteristic impedance, it is important to take this into account when designing the optimal EIS cell configuration. The effect of cell geometry on EIS was determined by varying the gel area (A) as well as the distance between the working and counter gel electrodes (l). Additionally, normalization to the cell constant (Kcell=l/A) allows for comparison between EIS spectra from different cell geometries, which may be necessary for certain field measurements. EIS cells with smaller cell constants are preferred because the measured impedance from both the gel and the coating will be reduced. Finally, EIS data was modeled using equivalent circuit elements to further understand the electrochemical behavior of both the gels and the protective coatings.
12:30 PM - PP3.07
Isotopic Labeling for the Understanding of the Alteration of Limestone Used in Built Cultural Heritage
Mandana Saheb 1 Anne Chabas 1 Anne Michelin 1 Jean-Didier Mertz 2 Estel Colas 3 Olivier Rozenbaum 3 Aurelie Verney-Carron 1 Jean-Pierre Sizun 4
1LISA Cramp;#233;teil France2LRMH Champs sur Marne France3ISTO Orlamp;#233;ans France4LCE Besanamp;#231;on FranceShow Abstract
This project belongs to a specific work aiming at developing isotopic tools to better understand the alteration of materials used in the built cultural heritage. It is focused on the study of the alteration of limestone used in the facades of historic buildings subject to atmospheric polluted environments. Actually in the elevated parts of the buildings, water as rainfall (runoff or wet deposition) or in vapor form (condensation or dry deposition) is the main agent of alteration. To establish its transfer within the porous limestone and locate the reaction preferential sites, two isotopic tracers (D and 18O) are used to monitor the alteration solution (D) and locate the zones containing the secondary phases (18O).
The Saint-Maximin limestone used in many monuments in the suburbs of Paris (France) as a building and restoration stone has been specifically studied. Healthy materials, stones from monuments (monuments in the Paris area) and samples altered in laboratory constitute the analytical corpus to compare different stages of alteration.
In a first step the stones are characterised at different scales to identify their alteration layout (SEM-EDS, Raman microspectrometry, XRD, rugosimetry) and study the water transfers (X-ray tomography, mercury porosimetry, imbibition kinetics). The samples are then altered in the laboratory by realistic and controlled wet or dry depositions using isotopically labeled solutions to locate the reaction zones by SIMS.
The location of these areas and their quantification will then help examining the role of the evolution of porosity and formation of alteration products within the material, in order to estimate the alteration rate and propose an alteration mechanism.
The methodology developed specifically for this study and the experimental results will be presented and discussed here.
12:45 PM - PP3.08
Internal Structure Characterizations of a Traditional Gesso by Focused Ion Beam Scanning
Michael Doutre 1 Ashley Freeman 1 Brad Diak 3 Alison Murray 1 George Bevan 2 Laura Fuster-Lopez 4
1Queen's University Kingston Canada2Queen's University Kingston Canada3Queen's University Kingston Canada4Universidad Politecnica de Valencia Valencia SpainShow Abstract
The movement of fluids within a porous medium is a function of the material type and the size and morphology of the voids. A major factor in an artwork&’s reaction to conservation treatment and a large influence on how the work will change with time is the movement of materials, such as the transport of substances between the paint layers or the diffusion of applied materials such as cleaning solutions. Of particular importance in the conservation of painted surfaces is the preparatory layer. Usually composed of gesso or some other primer, this layer is generally many times the thickness of the paint layers and highly porous making it a very active in the transport of materials within the artwork. In this study a gesso film comprised of fine calcium carbonate particles bound with collagen, typical of the preparatory layer of many painted works including the vast majority of easel paintings, was characterized using a Micrion 2500 focused ion beam (FIB) instrument. The gesso was milled and scanned with gallium ions serially in sequential planes orthogonal to the plane of the film to yield quantified measurements of the internal structures at a resolution far higher than previously reported for this type of material. From this a greater understanding of the geometry of the internal surfaces was gained, increasing understanding of the mechanics of capillary flow and diffusive behaviour in this extremely common and significant material.
Pamela Vandiver, University of Arizona
Weidong Li, Shanghai Institute of Ceramics, CAS
Philippe Sciau, Universite de Toulouse
Christopher Maines, National Gallery of Art
PP7: Glazes and Bodies
Wednesday PM, December 04, 2013
Hynes, Level 3, Room 301
2:30 AM - *PP7.01
''Hare's Fur'' and ''Oil Spotrdquo;? Study of Ancient Black-Glazed Jian (Temmoku) Wares
Catherine Dejoie 1 Weidong Li 2 Philippe Sciau 3 Apurva Mehta 4 Benjamin Kocar 4 Samuel Webb 4 Kai Chen 5 Martin Kunz 6 Nobumichi Tamura 6 Zhi Liu 6
1ETH Zurich Zurich Switzerland2Chinese Academy of Sciences Shanghai China3CEMES-CNRS Toulouse France4Stanford Synchrotron Radiation Lightsource Menlo Park USA5Xi'an Jiaotong University Xi'an China6Lawrence Berkeley National Lab. Berkeley USAShow Abstract
The Black glazed “Jian ware”, also known in Japan as “Temmoku ware”, was produced in Jian Kiln located in Jianyang of Fujian Province. The black glazed pottery was produced in China as early as Eastern Han dynasty. Its production increased significantly in the Song dynasty (960-1279 A.D.) especially with the making of high quality black-glazed tea bowls. Jian tea bowls were highly desirable not only due to the thick and lustrous black glaze but also the spectacular glaze effects as ''hare's fur'' and “oil spot”. Some finest examples of Jian ware were also brought to Japan by Buddhist monks. Several of them, Yohen tenmoku (Inaba tenmoku), belong to the national treasures of Japan.
The origin of the different colored patterns at the surface of Jian tea bowls, in relation with the glaze composition and the firing procedure are still not well understood. The objective of our project is to investigate the correlation among composition, microstructure, firing technique, and glaze appearance. The external appearance and the characteristic patterns of the Jian wares are believed to be related to the decomposition of hematite during the high temperature firing process. O2 released from rich hematite region will form bubbles. As the bubble grows in size and moves up, it will carry iron to the surface. Condition of crystallisation of iron oxides at the near surface is then a key point to decipher the scientific mystery behind the aesthetically pleasing appearance of Jian glazes.
We have carried out investigations using X-ray microdiffraction (ALS-BL12.3.2,Berkeley), X-ray micro-fluorescence and micro-XANES (SSRL-BL2-3, Stanford), micro-Raman and electron microscopy (CEMES, Toulouse) on several Jian ware samples. The glaze can be described as a Si-Al semi-opaque glass, in which micrometric dendritic crystals and nanoparticules of iron oxide are dispersed. Several thin cross-section samples show a 1-2µm crystallyzed rich-Fe layer beneath the surface, which is consistent with the reported formation mechanism. Furthermore, XANES spectra at the Fe K-edge did show that Fe in the silver “oil spot” is significantly more reduced than that of the brown “hare&’s fur”, in relation with the firing condition of the ceramics. The origin of the changes in the visual effects results from the combination of the chemical state of iron along with the distribution and particle size of iron oxides at the surface of the glaze.
 Weidong Li et al., Ceramics International 34 (2008) 1473.
3:00 AM - *PP7.02
Distinguishing Handmade and Wheel Thrown Pottery Using X-Ray Diffraction
Lesley Frame 1 Sarah Doherty 2 Ian C. Freestone 2
1University of Arizona New Haven USA2Cardiff University Cardiff United KingdomShow Abstract
The potter&’s wheel is one of the most significant innovations in the history of ceramics. Its adoption has been related to increased craft specialisation and changes in social organisation. However, our understanding of the introduction of the wheel in many cultures is unclear. Characteristic surficial evidence of the wheel has frequently been obscured by finishing techniques, and devices such as the tournette blur the distinction between hand-made and wheel-thrown fabrication methods. Methods proposed to distinguish fabrication techniques include thin-section examination, macroscopic examination and in particular X-radiography. However, all have limitations, which may include a perceived element of subjectivity in the method, the requirement for whole pots or large sherds for examination, and the need for large elongate inclusions or voids in the ceramic fabric which track the applied fabrication pressures. New approaches are required, which are widely applicable, require relatively small and easily transportable sherds, and which offer the possibility of an objective assessment of the likelihood of wheel use.
We have piloted the use of X-ray diffraction in the assessment of pottery fabrication methods, based upon the preferred orientation of platy minerals (e.g. sheet silicates) in the pottery fabric. The relative intensities of the reflections from the 001 crystallographic plane, parallel to the main (perfect) cleavage plane of the mineral, and crystallographic directions perpendicular to this (including 110, and 020 for most sheet silicate minerals selected for this study), may be compared with the relative intensities in randomly oriented grains from powder diffraction data. When analysed along the plane of preferred orientation (e.g. the surface of a wheel-thrown pot), the relative intensity of the 001 reflection increases with increasing alignment of the mineral particles.We have cut sections of archaeological and replica sherds, made using coil, pinch, slow and fast wheel methods, and analysed along six orientations at and below the surfaces of the vessels. Selected reflections were measured using a PANalytical X&’Pert Pro X-ray diffractometer (XRD), operating with CuK#61537; radiation at 40 kV voltage and 30 mA current, 5mm divergence and 3mm receiving slits, in the 7-26° 2theta; range, scanning at 120s/step, and using a RTMS X&’Celerator detector. Results indicate strong orientation at the surfaces of both wheel-thrown and several of the hand-made pots. However, in the centres of the walls, there are clear differences between forming methods. These results call for a systematic evaluation of the enhanced capabilities of non-destructive synchrotron X-ray diffraction in the measurement of preferred orientation in ceramics.
4:00 AM - *PP7.03
Quantitative Porosity Studies of Archaeological Ceramics by Petrographic Image Analysis
Chandra L. Reedy 1 Jenifer Anderson 1
1University of Delaware Newark USAShow Abstract
Pores in archaeological ceramics can form in a number of different ways. Porosity is a reflection of the raw materials selected by the potter, of clay processing and fabrication methods, and of drying and firing regimes. Some ceramics are deliberately designed to be porous for certain functions such as cooking or water storage, while others are designed to be impermeable to liquids, with low porosity. Porosity can impact the performance characteristics of a vessel, and also has implications for understanding the extent of deterioration and for developing and evaluating effective conservation treatments. There are a variety of traditional methods for characterizing porosity of archaeological ceramics both directly and indirectly. However, using digital image analysis of thin sections holds a number of advantages: the thin sections can also be used for qualitative mineral identification, quantitative analysis of non-plastics, and the study of structural aspects that relate to fabrication and decorative choices. With archaeological ceramics we rarely want to sacrifice the amount of sample material that may be required for performing tests found in ISO or ASTM standards for assessing porosity, so the relatively small sample size needed for thin sections, and the usefulness of those thin sections for addressing other research questions, are important considerations. Image analysis of petrographic thin sections has been demonstrated to provide comparable results to optical point counting and micrometer measurements, but is much faster, allowing for inclusion of a larger number of areas and specimens in quantitative work. While thin sections have been considered sufficient for analysis of macroporosity, the resolution has usually been considered insufficient for measurement of microporosity. We will present the results of experiments aimed at improving resolution of the smaller pores, using varying lighting conditions and ultrathin sections. This is especially important because questions have been raised about the reliability of image analysis of SEM-generated images for porosity studies due to variations in parameters (magnification, voltage, working distance, and detector type). We will examine the reproducibility of petrographic image analysis of ceramic thin sections using laboratory-prepared specimens of known recipes, and will outline the preferred protocols for measuring Total Optical Porosity, pore size (as a useful predictor of median pore throat aperture), and pore shape (aspect ratio and roundness) using the Image-Pro Premier software package. These procedures will be demonstrated with a variety of archaeological ceramics ranging from low-fired to high-fired wares, with discussion of possible interpretations of results.
PP8: Architectural Conservation and Underlying Technologies
Wednesday PM, December 04, 2013
Hynes, Level 3, Room 301
4:30 AM - *PP8.01
Properties and Characterization of Building Materials from the Laosicheng Ruins in Southern China
Ya Xiao 1 2 Ning Wang 2 Haibin Gu 1 Weimin Guo 1 Feng Gao 2 3 Ning Niu 4 Shaojun Liu 2
1Cultural Relics and Archaeology Institute of Hunan Province Changsha China2Central South University Changsha China3Chinese Academy of Cultural Heritage Beijing China4Henan Research Institute of Ancient Architecture Protection Zhengzhou ChinaShow Abstract
As one of the most typical ancient cultural relics in southern China's minority regions, the spectacular Laosicheng ruins excavated recently have been included in the UNESCO World Cultural Heritage Tentative List. Urgent conservation of the excavated Laosicheng ruins brings about the need for a study of the formulation and properties of building materials used, including earth, stones, mortars, and bricks et.al. In the present study, comprehensive analyses were carried out to determine their basic physical properties, raw material compositions, mineralogical and microstructural properties using sheet polarized light optical microscopy, scanning electron microscopy with energy dispersive spectrometer, thermogravimetric/differential scanning calorimetry, X-ray powder diffraction, Fourier transform infrared spectroscopy, and ion chromatograph. Special attention was paid on mortars that were the most widely used in building the Laosicheng. Results showed that mortar used as external render of the city wall was mainly built up from inorganic CaCO3 and MgCO3 based hybrid materials transformed from the carbonation of Ca(OH)2 and Mg(OH)2 with a small amount of sticky rice. Further investigation showed that sticky rice played a crucial role in forming dense and compact microstructure of mortars and effectively hindering penetration of water and air into mortars. In contrast, mortar used to bond the stones of the city wall was a kind of traditional mortar that did not contain sticky rice. This study is a part of a huge interdisciplinary project aimed to clarify the role of organics in ancient China organic-inorganic hybrid mortar, which can be considered as one of the greatest invention in construction material history. These results also provide valuable basic data and restoration strategies that can be used in the conservation of the ruins in southern China.
5:00 AM - PP8.02
Plaster Technology of the Great Standing Buddhas of Bamiyan, Afghanistan
Pamela B Vandiver 1
1University of Arizona Tucson USAShow Abstract
In 2002, the two great Standing Buddhas of Bamiyan were shelled by the Taliban. The damage was surveyed and some small damaged samples were presented to the Smithsonian Institution for further study and an assessment of deterioration. This paper reports the results of a technical study, and relates the analyses to the French Afghan archaeological excavations of the 1920s. The plaster technology was varied and adapted to satisfy various functional and performance criteria, including ancient repairs. Composite materials were formulated from a variety of locally available materials, including lime plaster, clay, sand, coarse rock aggregate from scree, horsehair, straw, and other field stubble. A wooden pin that held repaired material along the lower part of the small Buddha was radiocarbon dated to 400 A.D. Analytical techniques included optical microscopy of the organic fibers, and SEM-EDS, XRD and DTA of the inorganic fractions. Even though the fragments had survived Taliban artillery attack with expected introduction of flaws, measurements of strength (MOR) give a lower limit. Comparisons were made to similar fabricated plaster materials, as well as to reference material.
5:15 AM - PP8.03
Unraveling the Nucleus of The Gran Piramide from Cholula, Puebla: A Composition and Microstructural Analysis of Its Adobes
Nora Ariadna Perez Castellanos 1 Lauro Bucio Galindo 1 Enrique Lima Munoz 2 Carlos Cedillo Ortega 3 Dulce Maria Grimaldi 4
1Instituto de Fisica, Universidad Nacional Autonoma de Mexico Mexico, DF Mexico2Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico Mexico, DF Mexico3Zona Arqueologica de Cholula, Centro INAH Puebla, Instituto Nacional de Antropologia e Historia Puebla Mexico4Coordinacion Nacional de Conservacion del Patrimonio Cultural, Instituto Nacional de Antropologia e Historia Mexico, DF MexicoShow Abstract
The Gran Piramide is located at the archaeological site of Cholula, Puebla, Mexico. This pyramid is one of the largest in the world because of the size of its platform. It was built from 30 to 450 AD by the Cholulteca pre-Hispanic culture. The archaeological site is mainly recognized due to the great mural paintings that are still preserved, and which have been subject of study through several years. However, the building material has not yet been completely studied, the pyramid is built with the earth construction system known as adobe; and due to its fragile condition, a more extensive study is needed to fully understand the behavior of the building and the mural paintings substrate, in order to propose conservation strategies.
The starting point to propose the materials used in its construction was the geological context of the area. The analysis performed include X Ray Diffraction (XRD) with Refinement by Rietveld method, Particle Induced X ray Emission (PIXE), Fourier Transformed Infrared spectroscopy (FTIR), 29Si and 27Al Nuclear Magnetic Resonance with Magic Angle Spin (NMR-MAS), Thermal Analysis, Optical and Scanning Electron Microscopy (SEM) and color measurements.
The results obtained from the original adobes have been compared with fresh soils from horizons related with pre-Hispanic activity. The results indicate presence of amorphous materials and neo-mineral formation besides feldspars and opal. The amorphous phases have been identified by NMR-MAS and SEM. There are differences in the composition from the adobe to the joints, mainly in the clay proportion, that can be distinguished by color and allowed to group the information acquired.
These results provide a first glance at the composition and microstructure of adobes from The Gran Piramide of Cholula, further studies involve soil physics methods and erosion tests to complete the task of having a comprehensive knowledge of the earth architecture of the pyramid.
5:30 AM - PP8.04
Nucleation, Growth and Acid Resistance of Hydroxyapatite Films on Calcite Substrates
Sonia Naidu 1 Jeremy M. Blair 1 George W Scherer 2
1Princeton University Princeton USA2Princeton University Princeton USAShow Abstract
Marble, a non-porous stone composed of the mineral calcite, is subject to chemical-induced weathering in nature due to its high dissolution rate in acid rain. This paper investigates the nucleation and growth kinetics of hydroxyapatite (HAP) on marble and its application as a novel protective coating to reduce the chemical corrosion of marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate (DAP) salt was reacted with marble, alone and with certain cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP microfilms on the mineral surface. Two other ammonium phosphate precursors (NH4H2PO4, (NH4)3PO4) were also investigated. Film nucleation and growth behavior was studied, as well as metastable phase evolution, using techniques such as environmental scanning electron microscopy, x-ray diffraction and electron backscatter diffraction. A novel acid resistance test was developed to compare the HAP treatment efficacy with existing treatments. The onset of nucleation, and the growth rate of the film, increased with cationic (calcium) and anionic (carbonate) precursor additions. The calcium and phosphate precursors also influenced metastable phase formation, introducing new phases. When compared to alternative treatments (viz., oxalate, tartrate), HAP was found to produce intermediate protection against acid attack, despite having the lowest solubility. This was attributed to porosity within the film, arising from its crystal growth mechanism that enabled the acid to access the underlying substrate.
5:45 AM - PP8.05
New Techniques in Limestone Consolidation: Hydroxyapatite-Based Consolidant and the Acceleration of Hydrolysis of Silicate-Based Consolidants
Sonia Naidu 1 Chun Liu 2 George W Scherer 3
1Princeton University Princeton USA2Princeton University Princeton USA3Princeton University Princeton USAShow Abstract
Limestone, composed of the mineral calcite, is susceptible to environmental weathering processes that cause weakening from disintegration at grain boundaries. This paper discusses the effectiveness of hydroxyapatite (HAP) as an inorganic consolidant for physically weathered Indiana Limestone compared to a commercially available silicate-based consolidant (Conservare® OH-100). A double application is also investigated, in which samples are coated with HAP followed by Conservare® OH-100. Finally, a technique to accelerate the hydrolysis reaction of the initially hydrophobic Conservare® OH-100 is also developed. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. To artificially weather limestone so that the damage found in nature could be mimicked in the lab, a reproducible thermal degradation technique was utilised. A mild wet chemical synthesis route, in which diammonium hydrogen phosphate (DAP) salt was reacted with limestone, alone and with cationic precursors, was used to produce HAP microfilms to consolidate the grains. The effectiveness of Conservare® OH-100 is investigated by applying it alone, and by following up with an ethanol-water rinse to accelerate the hydrolysis reaction. Samples that were to be rinsed were left to hydrolyse naturally over two or seven weeks before being reacted in the ethanol-water mixture. The dynamic elastic modulus (a measure of stiffness), water sorptivity and tensile strength of the treated stones were evaluated. HAP was found to be an effective consolidant for weathered Indiana Limestone, as it restored the modulus of damaged stones to their original values and exhibited superior performance to Conservare® OH-100. Rinsing the Conservare® OH-100-treated stones increased their hydrophilicity significantly, although not to the level of DAP-treated stones, as determined by water sorptivity. The formation of the consolidants in the pores and at grain boundaries were confirmed by environmental scanning electron microscopy (ESEM) and energy-dispersive X-Ray spectroscopy (EDX).
PP6: Technology and Preservation of Ceramics and Glasses
Wednesday AM, December 04, 2013
Hynes, Level 3, Room 301
9:30 AM - *PP6.01
Ancient Chinese Glaze--Composition,Microstructure, Color and Feel
Weidong Li 1 2 Xiaohan Liu 3
1Shanghai Institute of Ceramics,Chinese Academy of Sciences Shanghai China2Key Scientific Research Base of Ancient Ceramics, State Administration for Cultural Heritage Shanghai China3Fudan University Shanghai ChinaShow Abstract
Ancient Chinese glaze is implicative and mysterious. Traditional ancient Chinese high-fired glaze falls into the category of calcium glaze or calcium-alkali glaze, originating from the plant ash glaze of the Shang Dynasty. The physico-chemical basis of Chinese high-fired glazes can be supposed within the confines of the phase equilibrium relationships of CaO-Al2O3-SiO2 ternary system and the metastable liquid-liquid immiscibility region in the system.
The color and feel of glaze is determined by its chemical composition and microstructure. Glaze feel can be described by its transparency and gloss, which is firmly related to the amount, size and distribution of the scatterers (bubble, crystal, liquid-liquid immiscible structure) exiting in the glaze as well as at the glaze surface. Factors affecting glaze color include chemical factor (coloring agent such as iron ion) and physical factor (structural coloring), which factor is predominate depends on specific cases. As for transparent celadon glaze, it is no doubt that Fe2+/Fe3+ ions determine the glaze color, and the body color beneath the transparent glaze also modify the visual effect of glaze color. While the coloring mechanism of opaque and translucent glaze is more complicated. Our latest research shows that, the mild blue colors of Jun glaze and Ru glaze mainly result from the amorphous photonic structures in the glazes, which is an important breakthrough in understanding the coloring mechanism of ancient Chinese glazes. Computer simulation of glaze structure and simulative calculation of optical properties has been carried out to establish the corresponding relationship between structure and reflective spectrum. Coloring mechanism for the glazes from the same kiln site, however, is not invariable. Because glazes with the same compositions may have different microstructures when fired at different temperatures (different thermal histories) or kiln atmosphere. Temperature or kiln atmosphere varies in different firing processes or at different positions in the same kiln. For example, Ru glazes with same compositions may appear to be different colors such as azure blue, sky blue, bean green, grayish green, moon white etc, I believe both ion coloring and phase-separation structure take effects in the coloration of glaze, while the micron-sized anorthite crystals in glaze just result in the opacification of glaze. The interaction and coordinated effect between ion coloring and structural coloring needs to be further investigated.
In ancient Chinese glaze, Fe is the most magical element which has multiple functions. Fe acts as both flux and coloring element, favors the strong immiscibility tendency between SiO2 and CaO, and precipitates from the glaze under supersaturation. Takes the famous Jian kiln ware as an example, Fe plays an important role for the wonderful exterior appearance of Jian glaze.
This study will help us scientifically understand the essence of ancient Chinese porcelain.
10:00 AM - *PP6.02
Ceramics at the Emergence of the Silk Road: A Case from Southeastern Kazakhstan
MaryFran Heinsch 1
1University of Chicago Chicago USAShow Abstract
Between the fourth century B.C. and second century A.D., changes in climate, culture and commerce converged to extend networks of influence and intensify social stratification in communities situated along the Silk Road. The horse-riding nomads and agro-pastoralists of what is now Southeastern Kazakhstan were important actors in the unfolding of these events. The settlements and kurgan burials of the Saka and Wusun could be found dotting the alluvial fans north of the Tien Shan Mountains just a short time before Alexander the Great founded outposts in the Ferghana Valley and Chinese emissaries formalized relations with their periphery. In other words, the appearance of Iron Age Saka-Wusun sites anticipated the formation of the Silk Road&’s northern branch and subsequently helped mediate long-distance relationships connecting East and West. Historical accounts appear to confirm the presence of the Saka and Wusun in this role, but there is much that remains unknown regarding relationships both within and across their communities. Typolgical variability in their material culture has fed speculation concerning their position within trade networks, but there has been very little in the way of materials analysis to test the validity of these assumptions.
The ceramics recovered at Tuzusai near Almaty provide an excellent opportunity for examination of the impacts and implications of extended regional contacts. Although a few imports have been identified, mineralogical and compositional analyses indicate that an extensive vocabulary of pot forms was locally produced. Some elements of this local production point to the influence of finishing techniques and aesthetics from outside the region. The importation not just of ceramics, but of production methods, suggests greater social permeability of Saka-Wusun communities than was previously proposed and allows us to understand the formative dynamics of trade on the Silk Road and the rise of nomadic steppe empires.
10:30 AM - *PP6.03
Technological Behavior in the Southwest: Pueblo I Lead Glaze Paints from the Upper San Juan Region
Brunella Santarelli 1 David Killick 2 Sheila Goff 3
1University of Arizona Tucson USA2University of Arizona Tucson USA3History Colorado Denver USAShow Abstract
Although widely employed in prehistoric Eurasia, lead glazes were produced in only two small regions of the Americas prior to European contact, both in the Southwest. Southwestern glaze paints are unique in that they developed as decorative elements instead of as protective surface coatings. The first independent invention of glaze paints was in the Upper San Juan region of southwestern Colorado during the early Pueblo I period (ca. 700-850 CE). Despite recent interest in the later Pueblo IV glaze paints of New Mexico (ca. 1275-1400 CE), there have been no technological analyses of the Pueblo I glaze paints. This research project presents the first analysis and technological reconstruction of the Pueblo I glaze paints. It is in the production of the glaze paints that the potters are innovating and experimenting with materials; the selection, processing and use of the lead-glazed materials developed as a culturally patterned behavior that connects the material to its symbolic and iconographic function. These early glaze paints have the potential to provide important information regarding both technology of production as well as the relationships and interactions of potters during this period in the Upper San Juan region.
This project aims at reverse engineering the technology of production of Pueblo I lead glaze paints. Over 300 samples of Pueblo I glaze-painted ceramics, selected from the Arizona State Museum and from the Animas-La Plata archaeological excavations, were analyzed using x-ray fluorescence (XRF) spectroscopy, backscattered electron (BSE) imaging and wavelength dispersive spectroscopy (WDS). A pattern of traits that involves raw materials, processing, properties and performance of the final product suggests the existence of a patterned technological behavior. Results provide a comprehensive survey of the technology and the social context of production of the earliest glazes in the Americas.
11:30 AM - PP6.04
The Technological Development of Decorated Corinthian Pottery, 8th to 4th Centuries B.C.E.
Jay Stephens 1 Pamela B Vandiver 1
1University of Arizona Tucson USAShow Abstract
Decorated pottery from Corinth, Greece, developed over centuries from monochrome, dark brown slips and washes on a calcareous yellow clay body to a wide range of decorative techniques that involved experimentation with innovative compositions, textures, colors, and decorative techniques. Some slip colors involve multiple-step processing, especially the control of glass content and sintering of the slip; the control of particle size to produce variable roughness and a matte or semi-matte appearance, others involve reprocessing of materials from another craft specialty. A post-fire paint was also documented. Once significant experimentation with color variability began, seven colors, each with various levels of gloss were produced. Although considerable evidence supports nearly continuous ceramic engineering of the decorative slips, no data support the improvement composition or processing of the ceramic bodies. For instance, significant macro-porosity is present consistently. We present results from the study of 200 examples of Corinthian decorated pottery sherds and clays collected by Dr. Marie Farnsworth from Greek archaeological site in the 1950s. Analytical techniques included scanning electron microscopy, wavelength and energy-dispersive spectroscopy, x-ray diffraction and differential thermal analysis.
11:45 AM - PP6.05
The 4000 to 6000 Year-Old Mesopotamian Tradition of Composite Ceramic Tool Manufacture at Nippur, Iraq
Pamela B Vandiver 1 Brendan Tobin 1 Leah Hearlihy 1 Rita Weinsettle 1 McGuire Gibson 2
1University of Arizona Tucson USA2University of Chicago Chicago USAShow Abstract
At 4000 BCE in lowland Iraq, ceramic sickles, hammars, axes and adzes were formed and fired using natural well-fluxed, calcareous seabed clay mixed with a coarse narrow particle-size quartz-sand that was high-fired between 1150 and 1200oC. By 2250 BCE only the ceramic sickles are present in the archaeological record. In 1989 in fields off the tell at Nippur in 20 minutes four of us were able to collect 120 fractured, worn sickles often with evidence of re-sharpening by flaking of the edges. Some sickles were overfired and bloated, adhered to one another during firing, often with evidence of subsequent use as hammarstones. Furthermore, overfired, vitreous ceramics were reused as temper, ground and added to bodies of large jars and some bowls whose use and transport required fracture toughness.
We have investigated this widespread Mesopotamian lowland technological tradition. Sickles and raw materials were characterized using traditional materials research techniques of petrography, SEM-EDS, WDS, XRD, and DTA. Processing, especially thermal history, was examined using Xeroradiography and SEM-EDS of sickles and replicates. Replicates were made from Iraqi raw materials from Nippur and nearly sites. Mechanical properties of replicate test tiles were investigated using 3-point bend to determine MOR. We have examined performance characteristics using sickle replicates to harvest orchard grass (hay) and wheat.
12:00 PM - *PP6.06
Technology of Egyptian Core-Glass Vessels
Blythe McCarthy 1 Pamela Vandiver 2 Laure Dussubieux 3 Alexander Nagel 1
1Smithsonian Institution Washington, D.C. USA2University of Arizona Tucson USA3Field Museum of Natural History Chicago USAShow Abstract
Multi-colored glass vessels formed around a core were made in Egypt and the eastern Mediterranean in the late third millennia to mid-second millennia BCE. Many researchers have studied their composition, microstructure and manufacture, and they have proposed various forming techniques; other researchers have attempted to replicate the various processes proposed. This study aims to compare the variability of core vessels from the collections of the Freer Gallery of Art with a collection of known manufacture using the analytical techniques of optical microscopy, radiographic imaging, compositional analysis and scanning electron microscopy with energy dispersive x-ray analysis.
12:30 PM - *PP6.07
Role of the Alteration Layer on the Degradation Kinetics of Medieval Stained Glasses in Atmospheric Medium
Aurelie Verney-Carron 1 Tiziana Lombardo 1 Anne Michelin 1 Mandana Saheb 1 Lucile Gentaz 1 Claudine Loisel 2
1LISA Cramp;#233;teil France2LRMH Champs-sur-Marne FranceShow Abstract
Medieval stained glass windows are often severely deteriorated as their composition makes them low durable. In order to better preserve these objects of the cultural heritage, it is necessary to understand and to model their alteration phenomenology and kinetics.
Apparent kinetics measured on ancient potash stained glasses (by dividing the alteration thickness by the exposure duration) range between 0.06 and 0.28 µm/year. However, the evolution of this rate is not well understood. On one hand, laboratory experiments or short-term exposure in real conditions lead to higher alteration rate (by 1 or 2 orders of magnitude), which suggests that the development of alteration layers could have a protective effect (diffusion). On the other hand, the characterization of altered layers on ancient glass (from French Monuments) has shown that a crack network developed on these layers (observed by SEM and X-ray tomography) and in some cases scaling causes a loss of material.
In order to understand the role of these alteration layers on the evolution of alteration kinetics, two methodologies were set up. First, ancient glasses were immerged in D2O and analyzed by SIMS in order to trace the circulation of water through the layer. The objective was to assess if cracks are a preferential way of water penetration compared to the porosity of the altered layer. Second, in order to measure the alteration kinetics and to understand the cracking phenomenon, field and laboratory experiments were performed in various conditions (sheltered or unsheltered from rain in the field / in continuous contact with rainwater or with drying cycles at the lab). Results show that cracks are caused by the growth of the alteration layers more than by the variation in the environmental conditions and they have a significant role on the alteration progress.