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1.
ABSTRACT

Calcarenite stone samples from a historic building (Bizerte, Tunisia) were collected and treated under different environmental conditions with several consolidating products: alkoxysilane (ethyl silicate), a surfactant-templated novel sol–gel, Ca(OH)2, and SiO2 nanoparticles. These were subjected to marine aerosol accelerated aging cycles and studied by several non-destructive tests and techniques to assess the stability of the products. Results show that weathering caused by salt crystallization is not inhibited but it is slowed down due to the enhancement of superficial mechanical properties (surface cohesion and micro-hardness) achieved after one month of treatments application. A high or low relative humidity of the consolidation environment significantly affects the final mechanical and aesthetical physical properties and therefore conditions the durability of the treated substrates, even producing higher damage than observed in the blank specimens, depending on the product.  相似文献   

2.
ABSTRACT

The main aim of our current investigation is the colorimetric evaluation of protective treatments (consolidants) applied to traditional Islamic plasterworks, under natural ageing conditions. From analyses of the original pictorial plaster remains in the Courtyard of the Maidens of the Real Alcázar in Seville, Spain (a World Heritage Site) we prepared test specimens, using materials and techniques similar to the original ones. We analysed 56 test specimens painted with four pigments (yellow, green, blue, and red), using two different binders (animal glue and gum arabic), onto which five representative consolidants were applied: barium hydroxide, acrylic copolymer, polyvinyl butyral, ethyl silicate, and bacterial carbonatogenesis. The test specimens were subjected to natural ageing for one year (indoors and outdoors), enabling a colorimetric assessment to be made of the changes of the polychrome surfaces. The colorimetric heterogeneity of the 56 specimens after ageing registered an average value of 2.7 CIELAB units, assessed using the mean colour difference with respect to the mean. In the aged specimens, the addition of consolidants resulted in average colour differences (mainly lightness differences) of 10.7 and 6.7 CIELAB units, considering as a reference the specimens without consolidants aged indoors and outdoors, respectively. These colour differences were very similar for both binders but not for the four pigments, higher values being found for the blue and red pigments. Considering as reference the samples without consolidants aged outdoors, we found no statistically significant colour differences, either among the five consolidants (p?=?.094) nor the two binders (p?=?.674) used. In addition to the magnitude of colour differences, the choice of the most appropriate consolidants must also consider aspects related to performance and effectiveness. Overall, for the type of paints tested, the polyvinyl butyral consolidant appeared to perform the best, followed by the ethyl silicate.  相似文献   

3.
《文物保护研究》2013,58(1):43-44
Abstract

The best material to be used in the restoration of a work of art is that most similar to the original. When grouting of lime-based wall paintings is necessary, lime-based grouts are the obvious choice. Compatibility is particularly important for grouting, as this is an irreversible operation. To set, lime-based grouts need air, specifically carbon dioxide, CO2. However, in the narrow space between two delaminating layers where the grout is injected, CO2 is not usually available in large enough quantities for this process to occur satisfactorily. To overcome this problem, extensive use has been made of hydraulic grouts, which set with water, and grouts containing synthetic or natural organic binders. A search was conducted for additives that would facilitate the setting of lime-based grouts, even at low CO2 concentrations. In this study, a group of substances that produce CO2 by reacting with water in an alkaline environment, esters of carbonic acid, were identified and tested to understand the kinetics of the setting process. Additives that would increase the fluidity of the grouting mixture, thus improving its injectability, were also investigated. The practical application of these grouting mixtures is illustrated by the recent restoration of Masaccio and Masolino's frescoes in the Brancacci Chapel in Florence.  相似文献   

4.
《文物保护研究》2013,58(1):179-183
Abstract

This paper deals with the approach to the conservation of a Spanish-style saddle and anquera (rump cover) from Mexico City and Puebla, Mexico, respectively. The objects were originally bought by an English explorer for a journey and are described in his book. The saddle and anquera are made from vegetable-tanned cowhide with punched and embroidered decoration and metal fittings. The condition, of the leather was assessed scientifically. It exhibits a number of conservation problems, notably surface deterioration and detachment of several sections due to acid attack. Previous conservation treatments have caused the leather to become overstuffed with dressing, resulting in a weakening of the substrate. The conservation ofthe saddle will involve four main stages: removal of excess dressing, stabilization of the leather, consolidation of the friable surface and repair of torn and broken areas. The suitability of various stabilizing agents, consolidants and methods of application was evaluated using mechanical tests alone and accelerated aging and mechanical tests. Naturall y aged and degraded leather was used as an experimental substrate. The results were used to formulate the approach to the conservation of the saddle and anquera.  相似文献   

5.
In recent years, there has been increased interest in examining alternative polymers for the conservation of archaeological artefacts, particularly waterlogged timbers, providing better, renewable, greener alternatives to poly(ethylene glycol) (PEG). The degradation of PEG consolidants in the timbers of the sixteenth century warship Mary Rose has been examined and the rheological and thermal properties of PEG have been compared with its monomethyl and dimethyl ethers and several polysaccharide consolidants (chitosan, guar, and 2-hydroxyethyl cellulose) in order to evaluate their potential as alternative consolidants for the conservation of waterlogged wooden artefacts. Additionally, the effect of the polymers on the archaeological wood was characterised by thermogravimetric analysis and solid-state nuclear magnetic resonance spectroscopy. The results suggest that the future of conservation technologies lies with polysaccharide consolidant materials, which show enhanced compatibility with wooden artefacts with no detectable side effects while also being cheap, with extremely low toxicity, renewable, and sustainably resourced.  相似文献   

6.
《文物保护研究》2013,58(4):227-236
Abstract

This article compares chemical dechlorination treatments (immersion in sodium hydroxide or alkaline sulphite) and electrochemical treatments of iron bars from the Gallo-Roman period excavated from a marine environment. Some important parameters, such as storage before treatment, temperature, solution composition, and drying after treatment, were varied during the study to assess their influence on the chloride extraction process. The kinetics of these treatments depend mainly on chloride diffusion through the corrosion layers. The kinetics are promoted by high temperatures and, in the case of electrolysis, by the electric field effect. The reduction of corrosion products during electrolysis occurs only for objects previously stored in air. In fact, the manner in which the objects are stored before treatment is critical in the dechlorination processes. The sooner the objects are treated after excavation (with water storage), the better the removal of chloride ions, in both chemical immersion and electrolysis treatments. But if the object is stored in air, material losses occur, and only electrolysis results in complete extraction of the chlorides. These differences are due to modifications in the corrosion products during storage. Drying after treatment also has a significant impact on the composition of the corrosion layers. If the objects are dried too quickly, Fe(OH)2 oxidizes into FeOOH, which thus forms a layer with low cohesion.  相似文献   

7.
The paper presents experimental research on the durability of a non-conventional technique for the repair of reinforced concrete damaged by carbonation-induced corrosion of steel reinforcement. The technique is called electrochemical re-alkalization and is often considered as an option for the repair of buildings, structures, and other artefacts made of reinforced concrete, for which conservation requirements are becoming increasingly important, in spite of their relatively young age. Absorption of a sodium carbonate solution is one of the processes that lead to concrete re-alkalization. The aim of the work is to investigate the contribution of this process to preventing future carbonation of re-alkalized concrete. Concrete specimens with six different compositions were initially carbonated, then re-alkalized through absorption of a sodium carbonate solution, and then exposed again to carbonation (re-carbonation). The results showed that the pH of concrete after re-carbonation was only slightly lower compared to that of re-alkalized concrete, highlighting a contribution of the treatment in preventing future pH reduction.  相似文献   

8.
ABSTRACT

To study the life expectancy and difference in aging resistance properties of different modern repair bamboo papers, hydrothermal/dry-heat ageing experiments on repair bamboo paper samples were conducted. The mechanical strength (tensile strength and folding endurance) of different papers during the ageing process were analyzed. Furthermore, the chemical properties (degree of polymerization and pH) of the samples were tested to search for the immanent cause of paper ageing. The results indicated that the ageing resistance ability and durability of modern repair paper are strongly related to their production process, which corresponds with the initial properties of the paper. Mechanical pulp had a low degradation resistance, which was further exacerbated by the chemical bleaching process. In the long run, traditional handmade papers with solar bleaching processes will have longer-term stability and durability.  相似文献   

9.
《文物保护研究》2013,58(1):26-30
Abstract

Thermoplastic resins such as Butvar B98 and Acryloid B72 used as consolidants in solution may retain solvents which lower the glass transition temperature and plasticize the polymer. These effect scan be minimized by using solvents with low boiling points. This study is part of a continuing effort to examine consolidation of deteriorated wood in a systematic manner.  相似文献   

10.
ABSTRACT

Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl2·6H2O:H2O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl2·6H2O:H2O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl2·6H2O:H2O?=?5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone.  相似文献   

11.
《文物保护研究》2013,58(4):133-137
Abstract

The condition before treatment and the subsequent consolidation of the wooden parts of an eighteenth century English fire engine are described. Experiments on a range of possible consolidants are outlined, and the application of polyvinyl butyral (Butvar B90, Monsanto) by both brushing and vacuum methods is presented. A closing discussion examines the relationship of the experimental findings to the practical application, the need for consolidation, and the final results of the treatment.  相似文献   

12.
The aim of this research work was to test the influence of stone properties, consolidation product, and application procedure on the potential harmfulness of consolidation on carbonate stones as assessed through the impacts on colour and water absorption kinetics. This article contributes to understanding the immediate and delayed impacts of consolidation treatments through the assessment of colour variation and modification of water absorption kinetics. The investigation was carried out on two limestones having a porosity of 10 and 27%, which were treated with three consolidating products (ethyl silicate, acrylic, and epoxy resins) using three treatment procedures: capillary absorption, brush, and full immersion. All products showed negative impacts at different degrees. We could show that their impact on a given stone depends not only on the consolidant type, but also on the treatment procedures. We demonstrated this way that the assessment of the potential harmfulness of a consolidation treatment for a specific intervention should be carried out in conditions as similar as possible to those expected to occur in practice and should never be based on extrapolations made from any other different conditions. The results also contribute to the definition of standard testing protocols in stone consolidation, privileging the application of a consolidant by direct contact capillary absorption when reproducibility is pursued, or by brushing when the potential highest impacts on colour are the target to evaluate.  相似文献   

13.
词汇集聚提供了文本的结构启示,因而在许多自然语言处理中有极为重要的应用。介绍基于知网分析词汇集聚的方法,首先利用语义网络的形式将知网知识表示出来;然后在文本概念间有引导地建立推理路径;最后基于路径搜索形成体现集聚的词汇链。测试表明,基于知网推理形成的词汇链基本符合人的直觉,准确率较高。  相似文献   

14.
Home entertainment markets have seen dramatic declines in revenues over the last 10 years due to the digital revolution, making new adaptation strategies of crucial importance to maintaining existing profitability. Recently, the film industry has worked with related firms to develop a standardized ecosystem for the sale and access to digital versions of their films. This system, known as UltraViolet, embodies infinite durability; the perpetual access to a purchased film across computing platforms and time. The author makes use of exogenous variation in the implementation of this system to study the effect the introduction of this new feature has had on the decision to buy or rent. His findings show that the inclusion of infinite durability creates enough value to spur increased purchasing behavior. Also, the inclusion of infinite durability creates a high degree of substitutability amongst products that include it in purchase markets. Lastly, the author found evidence that the lack of inclusion of infinite durability will spur consumers to rent rather than buy.  相似文献   

15.
《文物保护研究》2013,58(4):177-182
Abstract

A moulding of the Sutton Hoo ship impression was taken, so that a complete record could be preserved after the final excavations which would necessitate destroying the impression. Plaster of Paris was used as a moulding medium. Experiments were made with consolidants and release agents. Wet paper towelling was used as a barrier between sand and plaster, clay protected the iron rivets. Work began in the burial chamber and progressed to stern and bow. Pieces were made approximately 66 cm square and butted up to each other. Ribs of the boat were moulded separately in 7 or 9 pieces. There were 85 pieces moulded altogether.  相似文献   

16.
《文物保护研究》2013,58(1):57-61
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.  相似文献   

17.
ABSTRACT

This research reports for the first time the inclusion of Oryza sativa straw, root, and husk as a vegetal additive in the fifth century CE decorative mud plaster of the Buddhist cave of Bezeklik. The investigation is based on the morphological, anatomical, and silica bodies study of the vegetal additives accomplished through a light microscope, stereomicroscope, Fourier-transform infrared spectrophotometer, and scanning electron microscope from the isolated fragments of the painted plaster, transported to India in the nineteenth century and presently housed in National Museum, New Delhi. Studies indicate that loamy sand soil sourced locally for the earthen plaster was mixed with paddy straw in the proportion of 25–30% by volume for cohesion and strength. The excess of sand and absence of clay-size particles in plaster is, however, causing disaggregation of the grains due to lack of cohesion. As locally available materials are preferably used for any plaster works, this study also raises the question – was ancient Bezeklik, now a desert of Northwest China, once a rice-growing area in addition to the crops of Triticum aestivum (wheat), Setaria italica (Foxtail millet), and Hordeum vulgare (barley) reported by many researchers, based on hypothetical environment recreation. This study will help prepare a compatible plaster for the restoration of fragile-painted plaster fragments.  相似文献   

18.
This article examines how radio talk shows can promote a sense of community among listeners and shape the narrative accounts of show participants. In "Coast to Coast AM" and "Dreamland," Art Bell has fostered the collective generation of conspiracy theories and narratives of the paranormal in a manner that strengthens the identification of his audience as a group in opposition to various projected cabals, and that has some similarities to the formation of "virtual communities" in rumor-filled Internet discussion vehicles. This article outlines how Bell's frontier imageries (associated with the "Great American Southwest" as well as with the Internet) construct a mythic framework that is compatible both with the iconoclastic perspectives of show participants and the kind of group cohesion in which threatened settlers "circle the wagons" for protection. On his shows and website, Bell projects the "quickening" of a new global order and prophecies large-scale technological and climatic disasters during which individuals would indeed want to band together.  相似文献   

19.
《文物保护研究》2013,58(2):134-153
Abstract

A broad outline of the considerations which arise with regard to the conservation of a museum collection of tapestries is given in this paper. The various types of damage to, and deterioration of, tapestries is discussed.

Various methods of washing and dry cleaning, and the equipment necessary for these procedures, are reviewed, and a caution is included as to the necessity of testing all dyes for colour fastness in both water and any solvent used for dry cleaning. The equipment, materials and techniques of repair are discussed; three methods of repair being currently used in museums and specialist workshops — re-weaving, stitching on to a backing and the use of synthetic resins for impregnation and adhesion to a woven support. It is suggested in conclusion that the optimum method of repair in museums is stitching on to a backing. More research must be undertaken into the use of synthetic resins, and re-weaving usually alters the original appearance of the tapestry.

Finally, the need for specialised conservation staff in a museum with a tapestry collection is emphasised.  相似文献   

20.
刘岭 《编辑学报》2014,26(6):579-581
传统科技期刊通常为科学交流的正式过程服务。在数字时代,基于Web 2.0的非正式科学交流对科技创新和凝聚科研人员发挥着越来越重要的作用;因此,科技期刊应当积极构建基于Web 2.0的非正式科学交流平台,以此推动科技创新和增强对科研用户的黏性,提升其学术影响力和竞争力。国外一些先进出版单位在这方面给了我们有益的启示。  相似文献   

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