A PRELIMINARY NOTE ON THE USE OF ADHESIVES AND FILLERS IN THE RESTORATION OF ANCIENT MATERIALS WITH SPECIAL REFERENCE TO GLASS

Abstract

We have reacted Georgia marble in sulfur dioxide (SO₂) enriched atmospheres and calculated the reaction rate constant. This constant was derived from surface reduction data, obtained by leaching thereaction product from samples exposed for different periods of time. Application of this constant to marble weathered in known ambient levels of sulfur dioxide (SO₂) and relative humidity, allows the prediction of the thickness of the resulting gypsum crust formed over a given period of time. We have found that the crust grows outwards due to calciumions which migrate from the interior and then react with sulfur dioxide at the sample surface. Thus, anytreatment of the sulfated marble should include the considerations that the crust only masks the marble surface and is not an integral part of the original sculpture, and that cavities exist in the underlying layer of marble from which the calcium ions were selectively depleted.     

NOTES ON THE CONSERVATION OF SCULPTURE,STONE, MARBLE AND TERRACOTTA

Abstract

Sulphuration is the main destroyer of marble, producing imaginary (not true) patina. Other reasons for the discoloration of marbles are discussed. Magnesium silicate saturated with de-ionized water is a safe and simple cleaner. Sintolite is advocated as an adhesive for marble rather than the general more fluid epoxy resins. Solid polyvinyl acetate is strongly advocated as the basis for sma1l repairs to internaIly housed marble. The consolidation of marble is discussed and a method for internal exhibits recommended. Conservation of unbaked clay is touched upon, and a method for the repair of terracotta suggested together with a process for the reproduction of a glazed frieze using a latex mould and epoxy-reinforced plaster casts. A few remarks are made concerning the dangers of cleaning alabaster with water. The commentary is of a general nature and is not intended as a strict blueprint for any particular object.     

SOME ASPECTS OF THE CONSERVATION OF WAX MODELS

Abstract

During the Italian Renaissance wax was used to produce polychrome relief portraits on a miniature scale. This use of wax as a material for finished sculpture was subsequently adapted to the production of tableaux, of anatomical models, of life-size wax-works and of wax dolls. This article gives a brief account of the techniques of this type of sculpture and describes problems of conservation and restoration. Methods of repairing, cleaning and restoration are discussed, and the article concludes with a full account of the restoration work carried out on an allegorical tableau by Gaetano Zumbo and on two 17th-century ecclesiastical dolls.     

Conservation of Australian Aboriginal Bark Paintings

Abstract

This work combines our observation that the details of marble statues that have already been lost from the calcite surface are preserved in the gypsum layer, with our research on the mechanism of marble sulfation, to lead to a consolidation of the gypsum, transforming it back to calcium carbonate (calcite) using carbonate ions in solution. Our research shows the mechanism of the conversion of gypsum to calcite, the rate determining steps being the desorption and diffusion of CO^2?₃ We found that the reproduction of the surface detail and the improvement of the mechanical properties was very satisfactory.     

The conservation and restoration of a processional image: The Christ of the Expiration

Abstract

This image is the work of the sixteenth-century sculptor Marcos Cabrera and belongs to the Brotherhood of the Expiration in Seville. It was made to be carried in procession during the Holy Week celebrations. When the statue came to the ICRBC in Madrid for treatment it presented serious problems due to the unusual material of which it is made — polychromed paper-pulp — and the unfortunate treatments to which it has been subjected. Metal strengthening rods had been inserted in the figure and the cross, as well as a polyester consolidating material which had caused further damage. The polychromy was covered with a thick layer of paint which had plasticized. A complete scientific analysis was carried out by an interdisciplinary team both before and during the treatment which had the aim of stabilizing the sculpture to enable it to fulfil its ritual function.     

Examination and treatment of a seventeenth-century Spanish polychrome sculpture by Jose Caro

Abstract

The sculpture of St Gines de la Jara in the collection of the J. Paul Getty Museum, dated 1692, is an outstanding example of the estofado technique of imitating brocade in gold leaf and paint. The life-size figure retains most of its original polychromy. In previous restoration treatments, there had been an unsuccessful attempt to simulate the estofado. The present treatment included a comprehensive technical examination, using X-radiography to identify construction techniques and cross-sectional analysis for the layer structure and materials. The decoration of the sculpture was carefully studied with the goal of understanding more clearly the technique of the estofador. A cleaning strategy was then devised. Where there were losses in the estofado, it was decided to aim for a chromatic compensation using watercolours, rather than attempting to duplicate the original process.     

Performance evaluation in image processing with GAPP array processor

The application of parallelism considering the field of image processing is an alternative to implement real time image processing. The data parallelism found in array processors simplify the mapping of this kind of problem as each processing element works on part of the image. The GAPP board (Geometric Arithmetic Parallel Processor) is a near-neighbor mesh architecture with 144 processors interconnected as a 12 × 12 bidimensional array. This work analyzes the performance of the GAPP board regarding image processing. The implementation of two image convolution algorithms and the analyses of the obtained results, as well as the utilization of the GAPP board in this kind of application and the performance achieved are discussed. The results found in this work are also compared to the results presented in [11]. Some ways to achieve a better performance of the GAPP array in this kind of application are also presented.     

Matching Index Expressions for Information Retrieval

The INN system is a dynamic hypertext tool for searching and exploring the WWW. It uses a dynamically built ancillary layer to support easy interaction. This layer features the subexpressions of index expressions that are extracted from rendered documents. Currently, the INN system uses keyword based matching. The effectiveness of the INN system may be increased by using matching functions for index expressions. In the design of such functions, several constraints stemming from the INN must be taken into account. Important constraints are a limited response time and storage space, a focus on discriminating (different notions of) subexpressions for index expressions, and domain independency. With these contextual constraints in mind, several matching functions are designed and both theoretically and practically evaluated.     

THE VIRGIN AND CHILD FROM THE CHURCH OF DAL (NORWAY)—EXAMINATION AND RESTORATION

Abstract

A polychromed sculpture was restored and examined. The shrine is made from pine-wood and the sculpture from oak. The ground consists of chalk and animal glue; the pigments are: azurite, a green copper pigment, yellow organic colouring material, orpiment, red lead, vermilion, red organic colouring material, iron oxide red, lead white and charred matter (charcoal ?). Metals used are gold and silver. The medium is on a drying-oil base to which a protein-containing material is added. Generally, the colours were built up in two layers. There is an extensive use of imitation gold, while the use of gold foil is limited to the areas of hair and the flowers on the garments.

In general, the wood in all parts of the object was in good condition and no general impregnation was needed. Cracks in the shrine were filled in with wood or rejoined. The sculpture, which was split in two, was glued together. The condition of the polychromy was relatively good, and only local treatment was required.     

The terracotta modelli of Palazzo Venezia in Rome: Investigation of the constituent materials for fundamental knowledge and to aid conservation decisions

This work presents the results of the investigation carried out on a group of terracotta sculptures (modelli) (sixteenth to eighteenth century) belonging to the extraordinary collection of Palazzo Venezia in Rome. The study, the diagnostic analysis, and the conservation work, were possible thanks to the grant supplied by the Getty Foundation of Los Angeles and by the bank Intesa San Paolo. The terracotta modelli had a practical function as they were of great use as sketches to the creation of the final masterpieces or as models for restoration. As a consequence, the terracotta models allow reconstructing the creative process of artists and restorers, fundamental to outlining the ancient workshop production. X-ray fluorescence spectroscopy, micro-stratigraphic investigation, Fourier transform infrared spectroscopy, and micro-Raman spectroscopy were chosen as useful techniques to study the morphology and composition of the surface-painted layers. Usually the surfaces were painted in order to simulate the materials of the sculpture for which the model was created, for example lead white was used to obtain a white surface simulating marble. But, often the models were re-painted to make them more attractive for the antique trade. So, several pigments have been found on the surfaces such as zinc white, Prussian blue, chrome yellow, and mono-azo pigment. In some cases, the characterization of the surface paintings was particularly important to the final decision about removing or leaving the surface paint in place.     

Decay and treatment of Macael white marble

Abstract

This paper reports the process of deterioration of the white marble used in the Alhambra of Granada, and its consequences. Variations in mineralogical composition, microscopic topology, hardness, compressive strength, propagation of ultrasonic waves, absorptIon and diffusion of water and properties related to the pore structure were studied. The relationships between these factors, the visible deterioration and possible mechanisms are discussed. A preliminary evaluation of some protective treatments was carried out. The results can also be applied to white Macael marble used in other monuments in an environment with wide fluctuations in temperature and relative humidity.     

基于隐马尔科夫模型的中文术语识别研究

基于对中文文本信息语法构成尤其是词性搭配的概率特征的分析,提出一种基于双层隐马尔科夫模型的中文泛术语识别和提取的思路和系统框架,并实现相关系统,基于训练语料对多个领域的文本信息进行术语提取测试。实验结果表明,所提出的基于隐马尔科夫模型的中文泛术语识别和提取思想具有较好的实践参考意义。     

The conservation and iconography of Viceregal paintings and sculpture: old problems and new approaches

Abstract

The reasons for the often poor condition of Viceregal paintings and sculptures are examined. The conservation of four works is described, chosen largely because they had typical problems and would benefit from recently developed techniques. The treatments were: the preliminary lining of very cupped paintings, before using moisture to stretch the original canvas and allow the paint layer to lie flat again; lining badly torn paintings on a thin, semi-rigid, transparent support and using the old stretcher, in order to preserve the structure and aesthetic impression of the painting as much as possible; masking to protect susceptible fine lines against solvent action during cleaning; blending disturbing passages of the paint layer like blanching, irreducible stains, singeing and pentimenti into the colour scheme without overpainting; repairing broken pieces of sculpture with bamboo dowels. The study is accompanied by an iconographical discussion of colonial works of art.     

Microbial calcification of gypsum-rock and sulfated marble

Abstract

A broth containing the sulfate reducing bacterium Desulfovibrio desulfuricans was used to treat samples of reagent calcium sulfate, gypsum-rock specimens, fragments from a marble monument with a black weathering crust rich in gypsum, and a marble monument with similar crust. Calcite was found to have formed on all treated surfaces suggesting that this microbe has the potential to clean crusted marble monuments whilst also regenerating calcite, the parent mineral of the marble.     

POLYCHROME SCULPTURE IN SWEDEN

Abstract

A survey is given of polychromed sculpture in Sweden. Historical aspects of the care of sculptures are discussed. Many retables have been imported from Lübeck and Antwerp. Polychromed sculptures are often well preserved because there was hardly any iconoclasm in Sweden. Many need treatment however due to various forms of neglect. A special case—the triptych of Kärrbo (c. 1500)—is described in detail from a technical point of view.     

Pattern-welding and Damascening of Sword-blades—Part I Pattern-Welding

Abstract

Marble specimens were impregnated with epoxy resins by first soaking the specimens in a solvent and then treating them, in steps, with increasing concentrations of the resin in the resin-solvent mixture. This resulted in impregnation to several centimeters’ depth into the specimen. Both impregnated and non-impregnated specimens were subjected to 3000 ppm SO₂ atmospheres in a dynamic system. X-ray diffraction and fluorescence studies to determine the deterioration quantitatively, revealed that transformation of the outer layer of non-impregnated marble into primarily calcium sulfite stopped after a maximum of 15 mole percent conversion under normal conditions of humidity. While certain impregnated marble specimens showed significant protection from SO₂ attack, other impregnated specimens revealed more reactivity than the controls. A partial explanation of this has been obtained by scanning electron microscopy which showed that the resin films on the surface were perforated. Coatings of certain acrylics provided some additional protection to impregnated specimens.     

Conservation and authenticity: Interactions and enquiries

Abstract

The possible meanings in conservation of the word authenticity are discussed and some different definitions are briefly evaluated. Recent research showing the brain reacts differently to the concepts of copy and authentic is reviewed. The relationship between cultural heritage charters and how authenticity has been employed in them is explored with examples from the Athen's Charter, The Venice Charter, The Nara Document, The San Antonio Declaration, and the UNESCO World Heritage Documents. Several examples are discussed in the text concerning the interactions between authenticity and restoration, employing the examples of ancient buildings and old master paintings. Some of the important writings on the subject of authenticity by scholars and art historians are reviewed. Criteria which could be used to evaluate the concept of authenticity in different cultural settings are discussed and these are illustrated with case studies taken from restoration carried out on ancient marble sculptures, the Sistine Chapel frescoes by Michelangelo, and the artwork of several prominent forgers. Given that concerns about the authenticity of art are multi-dimensional, it is important that the present fragmentation of the arguments concerning authenticity across the disciplines properly take into account the conservation field and are aware of the debates within conservation concerning this topic. The questioning of the relevance of authenticity is a healthy process, and may now be framed quite differently from the way in which it was discussed even 20 years ago.