共查询到20条相似文献，搜索用时 25 毫秒
1.
《文物保护研究》2013,58(3):155-171
AbstractThe presence of iron oxides (lepidocrocite, goethite) in archeological wood may result in a degradation of the wood matrix. Extraction of these iron oxides is largely dependent on their solubility. In this study, balsa wood samples were impregnated with iron oxides to test extraction treatments. Additionally, archeological wood samples were also examined to determine treatment efficiency. Electrophoresis and simple immersion treatments were performed using various chemical solutions: a neutral and a conductive substance (potassium nitrate), an acid (acetic acid), three alkaline chelating agents (tri-ammonium and tri-sodium citrate and sodium oxalate), three acidic and slightly acidic chelating agents (ethylenediaminetetraacetic acid (EDTA), citric acid, and oxalic acid), and a reductant (sodium dithionite). Potassium nitrate did not extract sufficient amounts of iron, irrespective of whether the treatment was conducted by electrophoresis or simple immersion; any observable dissolution was attributed to protonation because of the acidic pH around the anode (as low as 3). Dissolution in acetic acid did not extract iron with either treatment. Strong chelating agents improved extraction, and these compounds gave the best results for simple immersion, particularly EDTA. This chemical is well adapted for use on archeological objects because of its chemical properties (stability constant, speciation based on pH). The addition of sodium dithionite to the solution improved dissolution. Even though electrophoresis improved extraction (in particular for tri-ammonium citrate), none of the tested chelating chemicals were suitable for electrophoresis because of a significant increase in temperature as well as high anode corrosion. The presence of iron sulfide in the archeological wood limited the effectiveness of the tested chemicals. A pre-treatment in sodium persulfate was expanded to include oxidized iron sulfide in oxy/hydroxide iron, which improved the extraction rate. 相似文献
2.
《文物保护研究》2013,58(4):274-284
AbstractA survey of stored waterlogged archaeological timbers from the Mary Rose revealed that 2% of these timbers were infested by larvae of the wharf-borer beetle, Nacerdes melanura L. Timber species attacked included oak, poplar and pine, with moisture contents ranging between 130 and 670%. In addition, scanning electron microscope studies demonstrated that wood tunnelled by the larvae was microbially decayed. The larvae and their life-cycle were studied and emerging adults were observed penetrating the 500 gauge polyethylene used to wrap timbers. Studies showed that 60 Nylon/100I Surlyn, 70 Nylon/125I Surlyn, T 1–19v, T 1–25x and Camvac were more suitable wrapping materials. 相似文献
3.
Natural polymers as alternative consolidants for the preservation of waterlogged archaeological wood
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
4.
This paper investigates chemical bleaching of wood to make species-specific practical recommendations for colour adjustment of veneer in furniture conservation. In more detail, chemical bleaching of Honduras mahogany (Swietenia macrophylla), European walnut (Juglans regia), Rio rosewood (Dalbergia nigra), padauk (Pterocarpus spp.), and purpleheart (Peltogyne spp.) is investigated using 11 different bleach solutions. Both oxidative (e.g. hydrogen peroxide and potassium permanganate) and reductive (e.g. oxalic acid and sodium bisulphite) solutions were used. The results show that the wood species react differently with the investigated bleach solutions. It can also be noted that not all investigated solutions were suitable for all wood species. Based on the results, wood species-specific bleach solutions are recommended. 相似文献
5.
Wood artefacts are subject to damage by biologic infestations due to bacteria, insects, and fungal species. One of the worst feared attacks is due to the xylophagous insects whose larvae feed on wood by boring galleries, at the expense of building timbers and worked woods. These beetles are responsible for daily destruction of the world’s wooden cultural heritage, and their elimination has been always a big problem for conservation of wood. The need to avoid the use of chemical methods in conservation for pest control has led to the development of various non-chemical, non-toxic treatments. Among these, heating with microwaves (MW) seems to be one of the most promising, since it has already shown its high efficacy in destroying pests. Insect-infested wood remediation by MW heating in conservation is based on the larger thermal increment induced in larvae than in wood, due to their different dielectric permittivity in the GHz frequency range. However, the side effects that may occur due to MW heating of wood, such as dehydration, have never been discussed so far. Here we study the possible application of microwave heating as a remediation method for wood samples infested by the larvae of the insect Hylotrupes bajulus. We show that it is possible to set up exposure conditions able to achieve 100% of larvae death and that are sufficiently mild not to induce significant dehydration of the exposed wood from which shrinkage effects may derive. Indeed, under these conditions, MW-induced wood dehydration on cubic and parallelepiped sweetgum samples can be kept under control and to percentages as low as 0.4% (w/w). 相似文献
6.
《文物保护研究》2013,58(4):157-167
AbstractThe winter climatic conditions of much of Canada provide an ideal environment for freeze-drying. We have been attempting to use these conditions for the drying of large waterlogged timbers. In the freeze-drying process the wood is kept in a frozen state and the drying proceeds by sublimation. We are particularly concerned with the treatment of large timber which present great difficulties when treated by the accepted methods. A structure was built to keep snow and rain off the wood but which allowed air to pass over it. The structure was covered with polyethylene sheet to allow the sun to shine on the wood surface and heat it. Weight changes in the wood were measured with a load transducer and temperature wa followed with thermocouple probes. Temperature and relative humidity of the surrounding air were recorded instrumentally. The timbers were of several varieties of wood in various states of decomposition. All of the wood dried quickly and much of the water was removed. This technique appears to have the potential to treat large quantities of timber in an economic and simple way. 相似文献
7.
《文物保护研究》2013,58(4):297-307
AbstractWet organic archaeological materials extracted from seawater may suffer damage as a result of degradation influenced by micro-organisms. One of the most common phenomena is indirectly induced by sulphate-reducing bacteria (SRB). Due to their metabolic activity in anoxic conditions, SRB generate hydrogen sulphide from sulphate ions present in seawater. When steel items are in contact with organic matter in presence of sulphides, corrosion of the metal leads to the precipitation of Fe(II) sulphides. These phases are responsible for dramatic post-excavation damage: their oxidation during storage or exhibition in museums leads to the formation of voluminous crystals, which may cause cracking and crumbling, and lead to the production of sulphuric acid. In order to characterize Fe(II) sulphides and their by-products, 13 waterlogged samples were analysed by environmental scanning electron microscopy, micro-Raman spectroscopy, and X-ray diffraction. Experiments were performed on untreated wood fragments, on a fragment of rope, and on mineral concretions scratched from the surface of wood remains, all extracted from different shipwrecks. Mackinawite was detected inside the fragments and between the fibres of the rope. Greigite was detected in scattered locations. Pyrite and sulphated phases, like gypsum and iron sulphates, were identified at the surface of the wood fragments and in the mineral concretions. 相似文献
8.
《文物保护研究》2012,57(1):28-36
ABSTRACTA pre-restoration diagnosis revealed a high amount of pyrite in the wood of the Lyon Saint-Georges 4 shipwreck (end of the second century). The occurrence of this phase is supposed to result from the microbiologically influenced corrosion of the iron fasteners. So, all the nails and metallic elements were removed from the remains before treatment and the wreck was consolidated by polyethylene glycol impregnation coupled to a specific desalination process. Treated and non-treated samples extracted from the wreck were studied in order to identify the iron/sulfur-containing compounds present in the wood before and after treatment and figure out its effect. Sample analyses relied on an original approach combining magnetic characterization methods and more common elemental and structural analysis methods. The results showed that the treatment was effective in removing soluble salts. However, a large amount of unstable iron sulfides remained inside the wood. 相似文献
9.
AbstractTwenty-two commercial coatings were chosen, based on their film-forming mechanisms, to study the equilibrium concentrations of volatile organic compounds (VOCs) and their emission rates at steady state. Concentrations of acetic acid (ethanoic acid) and total VOCs were measured using a thermal desorption unit coupled with a gas chromatograph. Almost all coatings released acetic acid, but at different rates. Coatings formed by oxidative polymerization were found to generate a high level of acetic acid at both equilibrium and steady state. The acetic acid equilibrium concentrations from the coatings formed by the other types of mechanism studied tended to be similar to those from red oak, an acidic wood. In a steady-state situation, most of the coatings applied on aluminium or on red oak had acetic acid emission rates lower than that of red oak alone, with the exception of the red oak coated with pigmented films formed by coalescence. The wide range of acetic acid equilibrium concentrations and emission rates for films formed by coalescence is due to the mixture of porous resin, extenders and free acetic acid in the formulations. Consideration should be given to allowing a sufficient drying period (three to four weeks) before using coated enclosures, in order to reduce the VOC concentrations within the enclosures. 相似文献
10.
《文物保护研究》2013,58(4):304-315
AbstractA 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. 相似文献
11.
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
12.
Probes for measuring oxygen concentration were installed inside large samples of conserved wood from archaeological shipwrecks to record oxygen profiles as a function of depth under the wood surface. The concentration of oxygen was lower inside the wood than outside indicating that the supply of oxygen is limited and that oxygen is consumed within the material. This was confirmed by oxygen consumption rates averaging 1.3 ± 0.42?µg O2/g wood/day. The diffusion properties were estimated by placing the wood samples in a nitrogen atmosphere and measuring nitrogen breakthrough time to the oxygen probes at different depths. A high level of variation was observed between the breakthrough times measured at different depths of the samples. This indicated that the access of oxygen is irregular, possibly due to wood heterogeneity and uneven distribution of conservation agent. By recording oxygen concentrations inside archaeological wood under stable environmental conditions, it was shown that oxygen concentration profiles are almost constant over a time span of seven years. This indicates that oxygen consumption, and thus oxidative degradation, is constant for an extended period of time. It also shows that the oxygen concentration inside conserved archaeological wood is a steady state value controlled by the local balance between oxygen supply and oxygen consumption. 相似文献
13.
《文物保护研究》2013,58(3):143-154
AbstractSince 1980, much research in the field of treatment and conservation of archaeological wood has been carried out at the Conservation Department, Faculty of Archaeology, Cairo University. Materials and methods used in conservation have been changing gradually over the years worldwide. It was necessary to study critically previous masters and doctoral dissertations on Egyptian archaeological and historic wood, all written in Arabic. This review of them includes a brief history of the Conservation Department at Cairo University and five main focal points of past research: types of wood used throughout Egyptian history, assessment of wood decay, wood properties and composition, treatment and conservation of decorated wood, and the evaluation of chemicals and polymers used in the treatment of archaeological wood and composite objects containing wood. 相似文献
14.
《文物保护研究》2013,58(2):65-79
AbstractEnvironmental standards for cultural heritage collections have been much debated in recent years. The interest in the issue has been driven by the growing movement towards green museums, that is, managing indoor museum environments in a responsible and efficient manner, especially in terms of reducing energy consumption and carbon emissions but at the same time maintaining high standards of collection care. Painted wood is among the category of heritage objects most vulnerable to relative humidity and temperature fluctuations. Therefore, scientific understanding of how changes in environmental conditions ultimately affect painted wood is crucial to the development of rational guidelines for the control of climate in museums and historic buildings. This review provides a systematic progression through two fundamental approaches to establish the allowable ranges of climatic variations – an analysis of the mechanical response of painted wood as a complex, multilayer system to climate variations, and an analysis of the historic climate to which the objects have acclimatized. The climate specifications and standards based on both these approaches are reviewed. 相似文献
15.
Martin Nordvig Mortensen Gilles Chaumat Francesca Gambineri Hartmut Kutzke Jeannette Jacqueline Łucejko Caitlin M. A. McQueen 《文物保护研究》2013,58(2):115-123
ABSTRACTSamples of conserved archaeological wood of different ages, origins, and conservation histories were aged in a climate chamber for seven months, while the humidity alternated between 30% RH for 12 hours and 80% RH for 12 hours at a constant temperature of 30°C. Photographs were taken once every hour, which enabled the creation of a time-lapse movie. Some samples degraded visibly, whereas others were unaffected. Most of the samples were robust and would be able to survive well even in a very poor museum climate. Among the sensitive samples, three types of degradation were identified, namely disintegration, pyrite oxidation, and efflorescence of white crystals. Disintegration was ascribed to dimensional changes caused by the RH alternations in very fragile wood. The white efflorescence was interpreted as the recrystallization of an alum-associated substance, possibly mercallite (KHSO4). The pyrite oxidation was observed as the efflorescence of a thick yellow, grey, and green powder. Characterization of selected samples was performed using X-ray fluorescence spectrometry, X-ray diffraction spectrometry, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma – optical emission spectroscopy, Fourier transform infrared spectroscopy, ionic conductivity – liquid chromatography, and pyrolysis-gas chromatography-mass spectrometry with in situ silylation using hexamethyldisilazane. 相似文献
16.
ABSTRACTPanel paintings are essentially wooden boards painted on one side. Due to the vapor resistance of the paint layer, changing ambient conditions lead to exchange of moisture on only one surface. Subsequently, a non-uniform moisture content profile is formed across the thickness of the board. As a result, differential expansion causes the board to bend in case of no mechanical restriction, or it leads to a build-up of stresses inside the material if restrained. Experiments with oak boards sealed on one side and exposed to a change in the ambient relative humidity (RH) were performed. By scaling, the response of any board with different thickness can be predicted. Since the bending of the board can be described as a linear system behavior, the frequency response can be predicted based on the step response. In combination with critical strains for wood and gesso from the literature, this gives insight into allowable RH fluctuations in terms of frequency and amplitude for different board thicknesses. 相似文献
17.
ABSTRACTConservation of wooden objects exposed outdoors is extremely difficult and complex due to their constant exposure to fluctuating weather conditions and biological degradation. Filling the gaps in such objects requires the use of specific materials that in particular can adapt to changes in wood dimensions in response to humidity variations. Various materials have been used so far for filling voids in wooden artefacts but none of them was entirely suitable. Therefore, the authors have attempted to provide the basic characteristics of the selected commonly used filling materials based on pine wood powder or glass microballoons as fillers and Paraloid® B-72, Klucel® G, or glutin glue as binders, as the first step in research aiming at developing new and more appropriate gap-fillers. Special attention was paid to the dimensional stability of filling materials upon drying and exposure to water vapour and liquid water. The overall results indicate that among the examined fills those consisting of Paraloid® B-72 and glass microballoons revealed best properties as they were relatively dimensionally stable upon drying and exposure to moisture – despite high absorption of water – and were quite easy to finish. Generally, better properties were observed for filling materials containing higher concentrations of adhesives and these materials will be modified in the next step of the research. Since the main drawbacks of the examined gap-fillers were low water resistance, poor dimensional stability upon drying or exposure to water vapour or liquid water, and fragility or friability, future research into their modification will head towards improvement of the above-mentioned properties. 相似文献
18.
Joseph R. Loferski 《Archives and Museum Informatics》1999,13(3-4):273-290
Because of the abundant forests of the world, wood is one of the most common materials found in historic buildings. Wood is relatively easy to fabricate into beams, columns, and roof systems using simple hand tools. However, because of its biological origin, wood is one of the most complex constructions materials. It is produced by thousands of different species of trees, and each type of wood has unique properties. Wood has an affinity for moisture and this can lead to biological deterioration caused by insects and decay fungi. This chapter presents information on understanding and preventing the mechanisms of wood deterioration in historic buildings. The chapter includes a discussion of wood preservation and technology, including wood finishes and wood preservative treatments, diffusible preservatives, and naturally durable wood species. A brief discussion about the repair of deteriorated timbers in buildings is also included. 相似文献
19.
Nesrin M. N. El Hadidi 《文物保护研究》2017,62(2):83-95
Hardwoods and softwoods were used side by side throughout Egyptian history, and importing softwoods that had an attractive color and texture was common. Over the decades, artifacts based on hardwoods and softwoods underwent deterioration phenomena, sometimes reaching either a level of brittleness or turning into a wood powder that may easily crumble. These levels of decay/degradation are often difficult to handle in terms of conservation treatments. To study or identify the reasons for decay has always been a point of interest for conservation purposes, but to assess decay and choose an appropriate treatment according to the state of preservation for the sake of keeping an artifact intact has become a subject of major importance. It is difficult at times to understand the deterioration process, because hardwoods and softwoods are different in structure, properties, and chemical composition. For this preliminary study, decayed samples from three commonly used softwood types, cypress (Cupressus sp.), cedar (Cedrus sp.), and pine (Pinus sp.), were identified and chosen. Scanning electron microscopy (SEM) of the samples indicated the degree of decay. Decayed and non-aged samples of the same wood type were analyzed using Fourier transform infrared spectroscopy (FTIR), and all the major carbohydrate and lignin bands were recorded. The strong hydrogen bonded (O–H) stretching absorption associated with water linked by hydrogen bonds to the –OH groups of cellulose and hemicelluloses in all decayed samples increased with decay. The brown powdery, fragile samples that had been evidently affected by microbial decay had a higher amount of lignin. The lignin/carbohydrate ratio was calculated and results compared. The increase of either lignin percentage or extractives in some of the samples had caused a darkening of color in both cypress and cedar samples, but the pine sample did not have the same texture and appearance. In cases where the lignin percentage decreased the samples had changed to a slightly lighter color. FTIR results explained the decay phenomena observed in SEM micrographs and helped assess wood decay and also confirmed results that had been previously obtained while applying traditional chemical analysis on wood. 相似文献