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1.
《文物保护研究》2013,58(4):298-313
Abstract

Five 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.
ABSTRACT

Research into dust deposition rates on the wall paintings in the State Apartments at the Palace of Westminster, London, UK, began during the restoration of the encaustic floor tiles. The study has broadened to inform day-to-day preventive care for the extensive fine art collections on display and the intricately decorated Gothic interiors, providing a powerful tool for the forthcoming restoration and renewal of the Palace. Different monitoring methods, using optical microscopy, macro-photography and software-based image analysis, were investigated. Qualitative analysis with SEM-EDX and optical microscopy allowed the identification of a number of anthropogenic, geogenic and biological sources of particulate matter, while quantitative results elucidated deposition trends, highlighting both seasonal and works-related impacts. Results indicated that mitigation measures taken to protect works of art and limit the diffusion and deposition of particulate matter on surrounding surfaces were successful. A new dust monitoring method, based on imaging of vertical surfaces and on a recently developed image analysis workflow (CHIJ) operated in open-source software (ImageJ) was trialled alongside more traditional methods for measuring dust deposition through collection of particulate matter on proxies. Results showed significant discrepancies between data acquired directly on wall painting surfaces as compared to horizontal glass slides. The advantages, limitations and complementarity of both monitoring methods were identified, and their potential contributions to the development of data-driven conservation approaches for heritage sites were assessed. The relatively low-tech methods and equipment used present useful and adapted tools for collection managers and conservators to inform their decision-making processes.  相似文献   

3.
ABSTRACT

Chalconatronite, Na2[Cu(CO3)]2·3H2O, is formed as a corrosion product when copper alloys are exposed to sodium carbonate solutions in the air. This also happens when metals come into contact with corroding soda glass which forms alkaline surface films in reaction with humidity from clean air. More often, substantial amounts of formaldehyde are present indoors which react to formate via the Cannizzarro reaction and accumulate over time in the films. Twenty cases of chalconatronite (including two mentioned in the literature) are reported as occurring on heritage objects with glass in contact with copper alloys: Baroque reliquaries with set glass gems, enamel on metal (sixteenth century and a modern replica of intentionally unstable composition), Christmas tree glass baubles with wires, glass buttons with metal shanks, a glass figure with a wire support, miners’ lamps, and a glass framed daguerreotype. These confirmed identifications might help conservators in investigating similar cases to shed more light on the formation conditions.  相似文献   

4.
A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu4Na4O(HCOO)8(OH)2·4H2O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses.  相似文献   

5.
Many painted surfaces, not necessarily only those with a contemporary binding media, display high sensitivity to water. The resulting damage, including swelling, leaching out of some components, even partial solubility, may lead to a shrunken, impoverished, de-plasticized, more porous paint film. Different approaches to the cleaning of such surfaces have been developed throughout the years, as awareness of this sensitivity grew worldwide. Some deal with the proper physico-chemical conditions of the aqueous solutions, and others with the proper ways of delivering these solutions to the surface. The strategy proposed in this technical note is concerned with the latter, the application stage, and is based on the combined and simultaneous use of a device capable of delivering a constant, precise amount of the aqueous cleaning solution and a surgical micro-aspirator to immediately remove the soiled solution from the surface and speed up its drying. Also, using a different apparatus, non-polar solvents can be delivered, for cleaning surfaces contaminated by non-polar, more lipophilic soiling materials.  相似文献   

6.
Unvarnished twentieth-century oil paintings are often sensitive to aqueous swabbing, a method routinely employed by conservators for surface cleaning. This study proposes a connection between sensitivity and the presence of magnesium sulphate heptahydrate which has been identified on the surface of some of water-sensitive paintings. The probable source of magnesium is magnesium carbonate, an additive in some twentieth-century oil paints, which has reacted with atmospheric sulphur dioxide (SO2). Films made using modern manufactured paints and formulations made in the laboratory were exposed to gaseous SO2 and raised relative humidity and examined using scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction to characterize the crystalline entities. Films containing magnesium carbonate formed magnesium sulphite and sulphate hydrates. Films containing zinc oxide were also investigated. These formed zinc and sulphur containing salts. Sensitivity to swabbing with water before and after exposure was evaluated. Films that developed salts, demonstrated increased sensitivity to aqueous swabbing after exposure to SO2. Findings suggest that increased water sensitivity may be due to a combination of the formation of hygroscopic degradation products and to weakening of the paint film due to salt-induced disruption of the surface.  相似文献   

7.
《文物保护研究》2013,58(1):20-3
Abstract

Severe corrosion was found covering the brass beads on several beaded belts. The corrosion was a mixture of copper soaps and zinc soaps, and was so thick in some places that it completely buried the brass beads. One of these belts was chosen as a test case for cleaning. The details of the cleaning are described, as are the effects of the corrosion process on the beads and surrounding organic materials. Two supporting studies are also reported: tests of the solubility of the corrosion in a variety of organic solvents, including mixtures of ethanol and petroleum-based solvents; and tests of leather dressings and other coatings on brass, copper, and zinc coupons in various relative humidities (RH), to determine what values of RH could be recommended for storage.  相似文献   

8.
Salt crystallization is recognized as a major cause of damage to porous building materials, threatening the sustainable preservation of our valuable built heritage. Unfortunately, the crystallization behavior of the detected salt mixtures is complex and not fully understood. While the deliquescence points of single salts are well documented, this is not the case for salts in a mixture where one is confronted with the presence of different cations and anions. In this paper the salt content of the murals and the limestone tracery of the main entrance porch from the sixteenth century church of St. James in Liège, Belgium is investigated and related to the climatic conditions of its environment. Concerning the salt load, the research consists of hygroscopic moisture content measurements, quantitative ion analyses, and the prediction of phase equilibria using the thermodynamic model ECOS/RUNSALT. This model can predict the salt crystallization sequences of a particular ion mixture. The output is mathematically evaluated with collected temperature and relative humidity data, which enables the calculation of the number of salt crystallization–deliquescence cycles. The results show that even small amounts of salts can cause damage over a long period of time when the environment causes frequent cycles of crystallization–deliquescence over time. It is shown how a mixture of small amounts of (double) salts, including hygroscopic ones, can have a significant effect on the decay of historic building materials in the case of daily changing climatic conditions and periods of extreme drought. As a result, the crystallization of double salts and hygroscopic salts such as calcium nitrate cannot be ignored. The scientific method and the results are described.  相似文献   

9.
《文物保护研究》2013,58(3):245-255
Abstract

The Minimalist work of Donald Judd exemplifies modern and contemporary works of art that utilize the appearance of bare metal as an integral component of the artist's intent. Decades after fabrication, disfiguring patterns have appeared on the surfaces of many such works. These patterns are not related to the formation of tarnish or other corrosion effects caused by improper storage, display, or transportation and handling; rather, they are associated with the initial processing of the metal sheets and subsequent fabrication of the art objects. Due to the challenges of obtaining analytical data directly from works of art, the authors present results from industrial sheet metal coupons prepared to simulate materials and techniques used in Donald Judd's copper and brass artworks. Attenuated total reflectance Fourier transform infrared spectroscopy carried out on each side of 55 coupons indicated the presence of organic materials such as long-chain aliphatic hydrocarbons, esters, and ethers, consistent with the types of compounds used in industrial lubricants. In addition to conducting the first systematic instrumental analysis of these residues, the authors propose the use of specific solvents for their removal as an alternative to abrasive methods, which cause removal of original surface from the objects.  相似文献   

10.
《文物保护研究》2013,58(1):112-115
Abstract

The preservation of the vast cultural heritage of tiles in Portugal requires the development of a systematic scientific and technological approach. In this communication the case of the treatment of a panel of ancient tIles is described. The main problem was the cleaning and consolidation of the piece, followed by restoration for exhibition. The treatment was preceded by a study of the materials, consisting of analyses of the ceramic body and the glazed surface. The removal of aged waxes and resins was achieved using appropriate solvents and the consolidation of the ceramic body was carried out by an inorganic treatment. For the reconstruction of missing parts and the mounting of the panel materials were chosen which would avoid interaction with the original material.  相似文献   

11.
Polysaccharide-based rigid hydrogels are by now well-established means for delivering water or, more generally an aqueous solution, to a surface in a controllable way so as to minimize diffusion and possible side-effects on water-sensitive materials during cleaning treatments. These gels can be applied as pre-formed solid bricks on planar surfaces or brushed onto objects in a semi-solid state. In this note, a different application procedure is presented, suitable for surface cleaning treatments of sensitive painted surfaces: pre-formed rigid gels grated to tiny particles that can be brushed onto the surface. A general discussion on the strategies that can be adopted when water is required to clean a water-sensitive soiled surface is presented, then the new procedure is discussed and a representative case study is shown, supporting the procedure described.  相似文献   

12.
《文物保护研究》2013,58(4):281-297
Abstract

Cellulose poultices are frequently used in stone and wall painting conservation for the purposes of soluble salt extraction, consolidation and cleaning. They have the reputation of being easy and pleasant to work with, have a neutral pH, high water absorption and plasticity, exhibit good conformance and adhesion to the substrate, and in most cases leave minimal residues after clearance. The cellulosic materials from which they are composed range from cotton wool, blotting paper or newspaper, to cellulose powders, the latter now by far the most common form of cellulose used today by conservators. Drawbacks of these products include poor water retention when applied to vertical surfaces, a tendency to redistribute salts further into the object substrate, and poor long-term treatment effectiveness for salt extraction. Hence cellulose poultices are used frequently due to good working properties, but apparently are in some situations not very effective. In this paper, existing knowledge of these poultices is outlined, followed by investigations undertaken to fill some of the knowledge gaps. Investigations include characterization of poultice properties such as pore size distribution and workability, and of moisture transport processes within poultice/substrate systems including moisture penetration depth, moisture distribution, and poultice shrinkage during drying. Cellulose powder products known under the trade name Arbocel®, extensively tested and used in conservation over several decades, were a particular focus. Resulting guidelines include counter-intuitive measures such as (when used for salt extraction purposes) the use of thinner poultices to reduce drying shrinkage and salt redistribution further into the substrate. The relatively uniform pore size distribution (around 10 μm) of Arbocel® poultices makes them more appropriate for salt extraction on substrates with a medium-coarse pore size (i.e. 15 μm and above), while on fine porous substrates (10 μm and below), the extraction will not be as efficient.  相似文献   

13.
《文物保护研究》2013,58(4):264-272
Abstract

The removal of calcareous accretions from archaeological bronzes can be a difficult step in their conservation. Chemical cleaning with chelating agents might be an alternative to mechanical methods. In this study the use of the chelating agent sodium tripolyphosphate (STPP) was examined to determine whether it is effective in discriminating between calcium carbonate and copper patina, and non-corrosive to copper alloys in the presence of air. Comparative experiments with STPP and disodium ethylenediamine-tetraacetate (Na2-EDTA) were carried out on synthetic malachite, cuprite, calcium carbonate, naturally polished malachite surfaces and sheets of bronze and brass. In addition to the properties of the chelating agent, the solubility of the salts and the pH values of the solutions are crucial factors in the removal of compounds of low solubility. The quantity of metal ions dissolved, estimated by atomic absorption spectral analysis and scanning electron microscopy, showed that the calcareous accretions could be removed satisfactorily, but STPP also dissolved constituent parts of the patina, such as malachite and cuprite, and may harm bronze or brass. Compared to Na2-EDTA, STPP is less effective in dissolving calcium carbonate. It is less harmful to the patina and base metal, but may lead to patination of the underlying metal.  相似文献   

14.
This study is part of a larger research project dedicated to digital print preservation issues – the Digital Print Preservation Portal (DP3). This work quantifies the potential of glazing materials to mitigate different types of light-induced damage – colorant fade, paper yellowing, changes in paper gloss, and loss of optical brightening agent (OBA) function – that occur to digitally printed photographs and documents when on display. Prints were subjected to xenon lighting to simulate daylight through window glass in a series of arrangements: without glazing, with plain framing glass (soda-lime) in a sealed or unsealed package, and with UV blocking glass in a sealed or unsealed package. Sealed packages served the purpose of isolating the samples from atmospheric pollutants, known to contribute to the deterioration of certain print types. In this study, the use of UV-filtering glass protected prints from colorant fade, paper yellowing, and paper gloss change to an extent. Protection conveyed by plain glass was less comprehensive and less effective than UV glass. Neither type of glazing was able to keep the OBAs functional by the end of the light exposure. It was also seen that light-induced damage to digital prints is due not only to UV radiation, but also to visible light, and that different digital prints may be more vulnerable to one or the other. Protecting sensitive prints from UV radiation and budgeting the amount of light they may be exposed to should be essential to any print display policy in order to ensure longevity.  相似文献   

15.
《文物保护研究》2013,58(4):184-188
Abstract

The pH dependency of turmeric, used as a dye or pigment on ethnographic objects from the Santa Cruz Islands, can present a conservation problem. Great care must be taken with the cleaning, consolidation, repair, storage and display of objects of this nature. A section on the analysis of suspected turmeric is included.  相似文献   

16.
纸质文献在长期保存和使用过程中,由于年代久远,环境中灰尘颗粒的覆盖、霉菌滋生、气体侵蚀等因素,泥斑、水渍、霉斑、油斑等在所难免。有些污渍会污染纸张,附着于纸张表面或渗透到纤维内部,影响纸张寿命;有些遮盖字迹影响阅读。清洗纸质文献的就显得尤为重要,是修复工作中非常重要的一项内容,是修补、托裱等修复工作的前期工作。中国自古至今所使用的清洁方法比较单一,水洗是常用的方法。本文针对国内外近些年来清洁技术、设备的研究、发展及其应用,在分析对比各类清洁方法的基础上,针对不同的污染物类型介绍具有实操性的技术与方法,以便于指导实际工作,填补我国清洁设备与技术的空白。  相似文献   

17.
This study focuses on the changes in properties of cellulose-based paper, which can take place as a consequence of its contamination by dust particles. The PM1 (fine) and PM10 (coarse) fractions of the dust particles from archival repositories were collected on cellulose filters Whatman 41, polytetrafluorethylene, and quartz filters. The latter two types of samples were subsequently analyzed gravimetrically, with ion chromatography, PIXE, and the thermal–optical transmission method, giving mass, ionic, elemental carbon, and organic carbon concentrations. After artificial aging, the viscosity-average degree of polymerization of cellulose (DPv) was measured. It was confirmed that cellulose-based paper can undergo substantial changes when contaminated by dust particles and artificially aged. The decrease of the DPv of cellulose showed a negative correlation with the deposited mass of sulfate ions in the dust particles. Considering the particle size fraction, the results suggest the decisive importance of the fine (PM1) particles. The results provide better understanding of how particulate matter contributes to the chemical degradation of cellulose-based paper. Such knowledge is of importance when considering appropriate conservation measures in archives, libraries, and galleries.  相似文献   

18.
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of art conservation. This technique provides high-resolution spatial maps of both inorganic and organic components located within cross-sectional samples collected from works of art. With recent advances in surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no interference by the presence of pigments. Furthermore, the layered systems that are often encountered in historical paint samples remain intact throughout the analytical procedure. This allows for the co-localization of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground). Because of this ability to localize the analytical signal to approximately 6?µm or less, the mass spectral information can be used to produce mass-resolved and spatially-resolve images which can be correlated to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist Matteo di Giovanni.  相似文献   

19.
《文物保护研究》2013,58(3):196-210
Abstract

Feasibility studies on applying laser radiation for the removal of superficial deposits from historic glass are being carried out within a three-year interdisciplinary project in Germany. Previous investigations revealed that there is insufficient knowledge about interaction processes between UV-laser radiation and individual surface layers of encrusted historic glass. Therefore, detailed studies were first carried out on special model glass samples to simulate different stages in the corrosion of historic glass. The potential of UV-lasers for removing crusts and biolayers, as well as layers of various conservation materials (due to previous conservation work) is examined. It is of great importance to avoid damage to materials such as gel layers, paint layers or the glass itself. A KrF-excimer laser operating at λ = 248nm is used for the experiments. A mask projection technique is applied for irradiation. A modified optical set-up has been designed, using cylindrical lenses for large-area removal by 'line scanning'. Removal rates and thresholds for the materials mentioned above are monitored. The collected data enable comparison and evaluation of the feasibility of removing superficial layers from historic glass artifacts. The results indicate that in some cases a closed loop process control will be necessary to avoid over-cleaning.  相似文献   

20.
ABSTRACT

This paper proposes a new way of interpreting particulate matter deposition indoors. The rate of deposition of dust in surfaces is presented as the result of the combination of two main factors: the concentration of suspended particles close to surfaces, and their capacity to deposit, expressed as the deposition velocity. We suggest that either of these two factors can be altered in order to mitigate deposition. The implications of this perspective are explored using in-situ measurements in a historic property (Apsley House, London) and a computational fluid dynamics model of aerosol deposition. The cases studied involve the effect of outdoor wind on the ingress of particles, the consequences of leaving the main door open, and the effects of the ventilation system on deposition. The results demonstrate that simulations can be used reliably to explore hypothetical scenarios or situations that would be experimentally challenging. The inputs and outputs of the computational model are discussed in view of its usability in preventive conservation.  相似文献   

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