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1.
《文物保护研究》2013,58(4):298-313
AbstractFive different methods for cleaning the limestone façades on what was originally the Workers Hospital in Madrid are analyzed in this paper. Due to the pollution in the surrounding air, just 20 years after a prior cleaning operation, sulfate crusts had developed on the entire stone surface of the building. The gypsum mortar used in the original masonry constituted an additional source of sulfur. Limestone is a traditional building material in Madrid and its surroundings. The petrography, mineralogy and petrophysical properties of the biomicrite, pelmicrite and biopelmicrite varieties of limestone identified in the hospital walls were determined. Analysis of a black layer on the stone surface showed that it consisted primarily of sulfate crusts. The cleaning methods tested were alkaline gels (sodium hydroxide and potassium hydroxide), pressurized hot water, glass bead blasting and latex peeling. The criteria for assessing the effectiveness and potential risks of the various cleaning systems included changes in the chromatic parameters of the stone, the formation of alteration products (i.e. salts) and modification of the stone surface. The stones cleaned with the three most effective methods, together with a rain-washed stone as a reference, were washed with water to generate an artificial runoff. The collected drain water was analyzed to determine the presence of any by-products from the cleaning process. The method found to be most effective and which caused the least alteration to the stone surface was glass bead blasting, particularly after adjustment of the bead size and pressure conditions used for the test. 相似文献
2.
《文物保护研究》2013,58(3):171-176
AbstractThe weathering of stone monuments results in the leaching of calcite, with a consequent increase in porosity and decrease in integrity. A new method of consolidation uses organic matrix macromolecules extracted from Mytilus californianus shells to induce the precipitation of calcium carbonate within the pores of the stone. The procedure has been tested in the laboratory on samples of bioclastic limestone and dolostone, by measuring changes in total porosity, amount of water absorbed and superficial cohesion. The results appear to confirm the success of the treatment. 相似文献
3.
《文物保护研究》2013,58(4):228-238
AbstractA procedure for collection of decay rate data from stone samples exposed in actual environmental conditions is described. This provides precise weekly decay rate data. Data were collected for 16 consecutive months for 200-year-old weathered and freshly quarried Portland stone. Problems with the use of an acrylic sheet as a control were encountered and overcome. It is suggested that glass is a better control surface. Decay rates of new and old stone differed, with new stone typically being 60–70mg/m2/day. Close agreement was found between new stone replicates. Rates for old stones were much more variable and ranged from 90–270mg/m2/day. Differences were also found in the relative contributions of solution and particulate loss to total loss between the two stones. 相似文献
4.
Ainara Zornoza-Indart Paula Lopez-Arce Karima Zoghlami Nuno Leal Joaquim Simão 《文物保护研究》2013,58(2):73-89
ABSTRACTCalcarenite 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
5.
Light-induced color changes and chemical modification of treated and untreated chestnut wood surface
AbstractThe aim of this work is to study the surface modifications of chestnut (Castanea sativa Mill.) wood by reflectance spectrophotometry and Fourier transform infrared spectroscopy (FTIR) in order to understand the mechanisms that cause changes and to suggest possible solutions to avoid degradation phenomena. The experimental data were statistically treated to evaluate their significance. Concerning the surface protection of wood, starting from the results obtained by testing different commercial products, attention was focused on a novel organic preservative/consolidant product (Linfoil®) that has attracted great interest in the field of conservation of wooden artifacts. Color monitoring showed that wood surface color undergoes an important variation due to photoirradiation, occurring within the first 24 hours and mainly due to L* decrease and b* increase. Though the protective treatment modifies wood color, nevertheless the product tested seems to protect the wood surface by reducing photoyellowing. FTIR analysis indicated that irradiation caused the degradation of lignin and increased the concentration of the chromophore groups on the wood surface. Changes in the chromaticity coordinates can be linked to the degradation of lignin and to increase of the concentration of carbonyl groups. 相似文献
6.
《文物保护研究》2012,57(1):37-58
ABSTRACTPlaster casts of ancient sculpture were widely collected by universities and museums through the nineteenth century. One of the intended functions of these casts was to preserve accurate 3D records of the sculptures, many of which were in remote locations around the world, often vulnerable to damage from weathering and vandalism. Gypsum plaster makes excellent casts, capturing fine surface details; however, it is also soft, porous, and easily damaged. This paper draws upon historical archives and patents to reveal the considerable efforts made during this period to create new techniques, recipes, and equipment to try to protect the casts. Case studies are selected primarily from the collection of casts put together by Walter Copland Perry in the 1880s, originally for the South Kensington Museum but transferred in 1907 to the British Museum. Samples were taken from a number of these casts and examined using scanning electron microscopy with energy dispersive spectroscopy. These results, combined with archival evidence, demonstrate that protective coatings were carefully applied in thin coatings to many of the casts. Barium appears to have played an important part in these protective treatments and further testing is recommended to evaluate the precise nature of its role. These treatments successfully protected the delicate surfaces of the casts for many years. However, later neglect means that these casts now suffer from a range of other threats to their condition. 相似文献
7.
《文物保护研究》2013,58(1):130-132
AbstractOriginal protective renderings have been the focus of numerous studies in recent years. Relevant literature, archival research and archaeological findings reveal that a number of mortar mixes or liquid substances were brushed on to protect and colour-unify the exterior ashlar-stone of many historic buildings. These coatings were of two types: common mortars, particularly improved with organic additives, and water-resistant filmforming substances. Economic cost, local supply, traditional practices and technological development are vital to an understanding of regional preferences for one mortar mix or material over another. The Cathedral of Leon is a mediaeval gothic temple from the thirteenth century, profusely remodelled throughout its history. In the sixteenth century, a new design of the courtyard partially enclosed a fifteenth-century exterior wall. Samples from the enclosed and exposed parts of this wall were examined. Analytical research suggests that the stone surface of this element received a treatment based on gypsum with organic additives. These organic products were fatty materials of the lipid type (tallow or lard) which reacted to form an insoluble, hydrophobic soap, at the same time providing the stone with its yellowish colour. The exceptional amount oflime registered in samples from the enclosed section has been considered a component of this surface treatment. 相似文献
8.
《文物保护研究》2013,58(3):163-170
AbstractThere is a need for a simple, rapid method which can be used with a minimum of equipment to evaluate whether microbial populations may pose a potential risk to the integrity of stone incorporated into buildings and works of art. Fluorescein diacetate (FDA) and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl tetrazolium chloride (INT) were compared for detection of microbial activity on stone, using both pure cultures of bacteria from stone and also natural stone samples. Both compounds could detect activity of bacteria and other microorganisms isolated from stone. INT-formazan was produced only by intact microorganisms whereas FDA was cleaved by extracellular enzymes as well. Use of FDA with stone samples was successful but INT required extended incubation times which gave little indication of in situ activity. A positive correlation was found between rapid cleavage of large amounts (> 15μg per gram stone) of FDA and production of INT-formazan after extended incubation periods. FDA was therefore found to be more appropriate as an indirect measure of metabolic activity of microbial populations on stone. The simplicity of the method makes it suitable for use by non-scientific personnel, with a minimum of scientific equipment, to identify stones at risk from active microbial populations. 相似文献
9.
《文物保护研究》2013,58(2):105-112
AbstractThe degradation of coupled building stones has been simulated in a laboratory chamber using an artificial acid rain solution (‘wet’ deposition) with wet/dry cycling. The reaction of individual and coupled stones with the artificial acid rain was assessed from the pH, and confirmed by measurement of calcium ion content in the run-off. For the coupled stones, it is evident that there is a build up of damaging reaction products in the region of the lower stone closely adjacent to the upper stone. This behaviour is related to the increased time of wetness due to retained solution, containing calcium ions from runoff and anion species from the artificial acid rain solution, which allows locally enhanced reaction with the lower stone and subsequent development of salts. Where Leinster granite is the lower stone of the couple, calcium ions in the run-off from the upper stone, Portland limestone, accumulate in these regions, leading to the eventual development of gypsum in the near-surface regions of the granite, with extensive resultant degradation. The laboratory chamber allows rapid ranking of various stone combinations in the couple, and early insight into the degradation process which may ultimately assist in the development of conservation procedures. 相似文献
10.
AbstractThe recent development of a phosphate hardening paste without oxalates, as well as consideration of the mixed calcium oxalate-phosphate composition of the hardest urinary stones, provide evidence to suggest that the formation of some patinas is the result of old protective treatments on stone surfaces. The formation of patinas with phosphates and oxalate scialbatura on marble and limestone is discussed as a contribution to the debate amongst conservators and scientists about the nature, composition and origin of these patinas. It is concluded that for the formation of both the inner part and the outer part of the patinas, the concurrent action of microorganisms and man is necessary. In both cases, man provides the foods and the microorganisms effect the transformation. 相似文献
11.
ABSTRACTOutdoor sculptures are part of the sociocultural identity of cities, but are extremely vulnerable to deterioration due to exposure to harsh environmental conditions and climate change. Furthermore, deterioration by micro-organisms renders urgent the need to design protective coatings. This research proposes an integrated methodology for the development of innovative and sustainable nanofilms for applications in the area of art conservation, very specifically in the preventive conservation of outdoor sculptures. Gathering objective data for the characterization of the surface microbiota is important in order to design strategies that make use of bio or nanotechnology innovative coatings. Methodologies for the characterization of the microbiota present in a granite outdoor sculpture, followed by preliminary results on the application of protective antimicrobial coatings for surfaces of cultural objects are described. 相似文献
12.
《文物保护研究》2013,58(1):50-57
AbstractThe conservation of roofing and cladding materials has both environmental and cultural heritage bearing. Our research aimed at comparing the performances of some polymeric products used for the protection of a typical Italian sandstone, the ‘Agro d'Ardesia’, used mostly as cladding, paving, roofing, and building material. These products belong to three different classes: polysiloxanes, acrylics, and fluoropolymers. In addition, an acrylic–silicone mixture was chosen for testing. After the application onto the Agro sandstone by capillary absorption, both efficacy and durability were assessed. Particularly, two types of weathering tests were performed to check the stability over time of the protective products: the exposure to ultraviolet radiation in a climatic chamber and the ageing by exposure to acid rain, expressly designed to represent realistically natural and anthropogenic changes. Detailed information on treatment performances was obtained. The polysiloxane was shown to be the most effective protective material for the Agro sandstone. 相似文献
13.
《文物保护研究》2013,58(4):242-248
AbstractDilute solutions of epoxy resins have been used successfully in the past to consolidate deteriorated, porous stone. However, the appearance change (darkening, yellowing) on curing has proved to be a deterrent to the wider use of these materials by conservators. In the study reported here, it is shown that solvent washing to remove surface-deposited resin and exposure to sunlight are effective methods for restoring the original visual appearance of consolidated outdoor stone. 相似文献
14.
《文物保护研究》2013,58(3):93-106
AbstractDuring 1977–78, a conservation project was undertaken by the Federal Government of Canada to preserve the weathered hull of the HD-4, an experimental hydrofoil craft built at the laboratorie of Alexander Graham Bell in Baddeck, Nova Scotia. After achieving a world marine speed record of 70·86 m.p.h. (114·01 km.p.h.) in 1919, the craft was beached on the shore of a salt water lake. Forty years’ exposure to severe weathering caused wood rot, metal corrosion and the disintegration of the canvas covering. Due to the deteriorated condition of the craft and the loss of most of the external structures, complete restoration was not desirable or practical. The aim of the project was therefore, to stabilize the wooden hull, while preserving its weathered appearance. 相似文献
15.
Salt decay is one of the harshest, most frequent, and more complex types of decay of porous materials in built heritage, including natural stones, ceramics, and mortars. In this article, we address the mechanism of thermal expansion, which is one of the least studied, yet most controversial, of those proposed over time to explain salt decay. We present a review of scientific literature on the topic, followed by a study of the effects of thermal expansion on a specific material, the well-known Ançã limestone. The study included experimental measurement of the linear thermal expansion coefficient of the Ançã, both in its natural state and with varying contents of sodium chloride, sodium sulphate, or sodium nitrate. The results show that this coefficient: (i) is significantly higher when the stone is contaminated with salt; and (ii) scales approximately with the amount of salt contained in the stone pores, regardless of the type of salt. Based on these results and on modelling of damage modes at the microscopic and macroscopic levels, respectively, we conclude that thermal expansion can cause powdering, disaggregation, or other types of decay consisting of internal loss of cohesion. However, it is not likely to cause exfoliation of salt-loaded layers. 相似文献
16.
《文物保护研究》2013,58(3):118-126
AbstractA series of corroded stone specimens from Salzburg monuments was examined by electron-probe microanalysis. The crusts arose from environmental effects, in the case of marble primarily from SO2. Deterioration phenomena can be correlated with stone surface features. 相似文献
17.
《文物保护研究》2013,58(1):49-58
AbstractBlack weathering layers on stone often contain iron. This is particularly true for the Turonian sandstones which were used extensively in architecture and sculpture in Saxony. In order to obtain more knowledge about the oxidic iron phases, samples were collected in the city of Dresden. Mineralogical and analytical characterization was provided for the black layers and the supporting stone. Material originating from Cotta and Posta stone was submitted to Mössbauer spectroscopy. After ample comparisons of Mössbauer parameters and evaluation of infrared spectra it was concluded that the predominant neogenic iron phase is not iron(III) oxide hydrite (ferrihydrite) Fe2O3·1·8H2O or jarosite KFe3(SO4)2(OH)6 or goethite α-FeO(OH) but a defectively ordered precursor of this last compound, characterized by different environments of the iron(III) ions. By the reducing action of organic matter, magnetite Fe4O4 is formed and this contains up to 45% of the iron present in a black layer. 相似文献
18.
《文物保护研究》2013,58(2):99-110
AbstractThe deterioration of stone monuments in urban atmospheres mainly involves corrosion by acid solutions. Thus the characterization of the material is of great importance in the understanding of stone decay. In this work, samples were taken from the balcony of the Metropolitan Cathedral (Mexico City), from three different areas of the facade of the National Museum of Tepotzotlán (NW of Mexico City) and also, for comparison, new fresh stone from the quarries of Chiluca and Los Remedios. Mineralogical, petrographic, chemical and structural analyses were carried out on all the samples, and a relationship was established between the degree of decay and the stone characteristics, such as porosity, specific surface area and calcium content. The characterization of the type of stone also influences the selection of conservation treatments. 相似文献
19.
《文物保护研究》2013,58(4):305-316
AbstractThe standing Buddha image of Jincheon in the Republic of Korea created in the fourth year of Taehwa is engraved on a darkgray rock wall of shale. The front face has a backward inclination, meeting the strike of N40°W almost vertically. The host rock contains well-developed fine laminations and stratifications, and has small and large discontinuous planes irregularly distributed. Exfoliations make it hard to make out each part of the body. The surface of the surrounding rocks is severely contaminated with lichen and Bryophyta, and plant roots aggravate the mechanical and biological weathering. The rocks went through a series of conservation treatments, which consisted of dry cleaning followed by wet cleaning using distilled water. Broken or cracked parts were filled in or glued together using epoxy resin, surfaces with exfoliations were treated with ethyl silicate to become water-repellent and hardened. The color of the repaired parts was matched to harmonize with the rest of the image. Drainage was created to divert rainwater from the slope above away from the image, and surrounding plants were removed to control lichen growth. The bedrock of the Buddha image is deteriorated in its functions due to the surface weathering, therefore it is necessary to implement long-term monitoring and to search for comprehensive conservation solutions. 相似文献
20.
由于月球是环绕地球运行的唯一的一颗自然卫星。对月球起源的研究不仅能够发现太阳系星球卫星的形成规律。而且可以揭示字宙星系的演进规律,进而控制星球的演进。因此许多人研究过月球,但是关于月球的起源仍然是一个不解之谜。于是本文作者通过分析和研究地球的演进过程,发现了地球卫星的形成机制．即地球岩石圈在水的长期侵蚀下分裂成一些断块．有的断块外部被溶蚀成许多溶洞,而内部又变成浮石结构,以致比重很小;当共中一个这样的断块的岩基被海水蚀透。使大量的水进入地慢与炽热的岩浆接触时．就会产生巨大的爆炸,将断块炸裂成多个浮石碎块,其中有些浮石碎块在巨大的岩浆喷射力的推动下经过大而深的岩洞可获得第一宇宙速度以上的飞行速度．从而进入绕地球运行的轨道。在这些进入绕地轨道的浮石碎块中有一块体积最大的浮石碎块就是后来形成月球的雏形。后来月雏不断地吸收地球周围的残余物质而变得越来越大．并渐渐地远离地球。 相似文献