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1.
《文物保护研究》2013,58(4):308-313
AbstractThe oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron-rich surface wood differs from the interior wood in that it displays higher pH and cellulose with higher molecular weight. The objective of this study was to determine why there is a difference in cellulose degradation, pH, and oxalic acid amount between the surface region and the interior of the Vasa timbers. Analysis of cellulose weight average molecular weight by size exclusion chromatography was performed, as well as quantification of oxalic acid and iron by high-performance anion exchange chromatography and atomic emission spectroscopy, respectively. It was found that a decrease in iron content coincides with an increase in oxalic acid concentration and a drop in pH at a certain depth from the wood surface. When iron-rich surface wood samples from the Vasa were mixed with an aqueous solution of oxalic acid, a fast increase of pH over time was observed. Neither interior wood poor in iron nor the fresh oak reference showed the same neutralizing effect during the time of measurement. This indicates that the presence of iron (rust) causes a neutralization of the wood, through the formation of iron(III) oxalato complexes, thus protecting the wood from oxalic acid hydrolysis. This effect was not observed to the same extent for other acids observed in Vasa wood (sulfuric, formic, glycolic, and acetic acids). 相似文献
2.
ABSTRACT Adsorbent materials can be used for the removal of organic acids from air in storage rooms with heritage collections. The organic acid removal efficiency of two commercially available activated carbon air-filters were tested in situ in two unoccupied stores with densely packed collections. One filter was designed for outdoor type pollutants (Filter A), while the other was designed for organic acids in indoor air (Filter B). Furthermore, the acetic acid removal efficiency of a desiccant silica gel rotor used for dehumidification was measured in a laboratory at different relative humidity levels. Finally, passive removal of acetic acid by silica gel and unfired clay brick were tested in a chamber, and for clay brick at room level as well. Filter B had the highest removal efficiency. The removal efficiency of both filter types depended on the airflow and the filter performance varied considerably in situ from the values reported from standard laboratory tests. Increasing the filter airflow reduced the removal efficiency from 77% and down to 7% for Filter A, and from 92% to 24% for Filter B. There was almost no effect of active air filtration on the concentration of organic acids when this was measured in the middle and in the corner of the storage rooms away from the ventilation inlets. The desiccant dehumidifier removed 98–100% of the acetic acid from the air, independently of the relative humidity. The desiccant rotor will, however, only be running when there is a need for dehumidification and as a result will only periodically remove pollutants. The high acid removal efficiency by dry silica gel was furthermore demonstrated in a chamber test. A clay brick wall in a test room established a concentration gradient across the room and reduced the concentration of organic acids by 56% compared to close to the emission source. 相似文献
3.
《文物保护研究》2013,58(3):169-173
AbstractA complete summary of equations for leakage of enclosures is given, including vapour diffusion through still air in openings, and infiltration of air/vapour/particulate mixture. Stack pressure due to temperature and relative humidity difference drives most infiltration. Experiments confirmed the diffusion and infiltration equations for small and medium-size enclosures. Leakage for a carefully made display case with ordinary materials has been reduced to the microbarometric limit of about 0·03 of an air change per day. Simplified tables and charts of leakage are given for 0·1, 1·0 and 10m enclosures, as a function of crack width, hole width, and wall permeability. 相似文献
4.
《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
5.
Stephen Hackney 《文物保护研究》2016,61(1):55-69
Acid-detector (A-D) strips were originally developed to assess the deterioration of acetate film stock, but they can also be used more generally within enclosures to detect volatile acidic pollution. A hand-held reflectance spectrophotometer was used to record the colour of individual strips in order to make consistent and reproducible readings. Calibration was carried out using the yellow-blue axis b*(D65) value in the CIELAB1976 system to measure the colour of A-D strips suspended in enclosed containers over solutions of acetic acid in combinations with glycerol to control the relative humidity (RH). A-D strips were found to be sensitive to changes in high RH (60–90%) but affected little by changes in lower RH or temperatures in the museum display and storage range. A-D strips can be used to establish the presence of volatile acids, record the indication of acid vapour concentration, explore conditions within a container, and to find sources of volatile acidity. They respond very quickly and several can be placed around an object. They therefore show promise for measuring slowly changing conditions, such as seasonal changes and the gradual accumulation of acidity in poorly ventilated containers and spaces. A-D strips proved useful in assessing air quality in storage and display enclosures. Examples and test results are presented. Well-sealed plywood transit frames and storage cases were found to be most polluted with volatile acids. Storage rooms with air filtration systems but filled with wooden objects had significantly reduced air quality. 相似文献
6.
《文物保护研究》2013,58(4):176-188
AbstractThe non-saponifiable fractions of the principal drying oils have been examined by gas and thin-layer chromatography and found to be qualitatively similar though varying in the relative amounts of sterols present. In the case of aged paint films it has been found that these sterols have largely disappeared from unpigmented films and those containing light red and lead white as pigment, though they survive quite well in the presence of verdigris. Similarly cholesterol was not found to survive well in egg tempera films. Doubt is felt as to the value of such analyses as an approach to paint medium identification. 相似文献
7.
《文物保护研究》2013,58(1):30-40
AbstractThe Kitora tumulus, which is thought to have been built around the late seventh to early eighth century, has beautiful mural paintings which were executed directly on a very thin layer of plaster in the stone chamber. When the paintings were found, the plaster was partly detached from the stone wall and the murals were therefore considered to be likely to fall off the wall with a casual touch or stimulation. Therefore, it was decided to detach the mural paintings and to store them flat and under controlled environmental conditions. This was initiated immediately after the excavation of the tumulus in 2004. However, fungal growth and biofilm development were observed within the stone chamber during the relocation work. In 2005, small holes containing black substances were observed on certain areas of the ceiling plaster, and following investigation an acetic acid bacterium, Gluconacetobacter sp., was isolated from the black substances. The bacterium was also isolated from the ceiling, floor, and east wall in the stone chamber in 2008 after the relocation of most of the paintings had been completed. These bacteria were shown to decompose calcium carbonate (CaCO3), one of the primary components of the plaster, and to produce organic acids such as acetic acid. Additionally, they were observed to decrease the pH of the culture media significantly in the presence of ethanol and glucose. This is the first example of the characterization of acetic acid bacteria isolated from decayed plaster paintings, and it is likely that microbes such as these bacteria have been involved in the deterioration of the plaster. Chemicals to treat microbes in the Kitora tumulus during the relocation work were selected on the basis of their antimicrobial efficacy, low potential to cause adverse effects on the paintings, and low level of toxicity to humans, depending on the condition of the plaster or stone in each area. However, some chemicals, especially ethanol, may act as a carbon source, which could encourage the growth of microbes and thereby the production of acids by the microbes when diluted to a low concentration or in a degraded state. Moreover, prior contamination by other microbial species in the form of a biofilm could also encourage the growth of the acetic acid bacteria by providing low-molecular-weight organic materials as a nutrient source. 相似文献
8.
《文物保护研究》2013,58(4):273-276
AbstractA new spot test for the identification of zinc white (zinc oxide) has been developed, using a silver-chromate reagent that produces a bright red colour. The nature of this red compound has been studied using both chemical and instrumental techniques. It has been found to be formed by chromate adsorption on the zinc oxide surface, and a tentative formula for the complex is given. 相似文献
9.
《文物保护研究》2013,58(4):257-266
AbstractA study of the accelerated light fading behavior of face-mounted color photographic materials has shown that alterations on the surface of the materials influence their fading characteristics. With the help of spectral density measurements it became apparent that the application of materials such as silicone rubber, adhesive film and acrylic sheeting, but also laminating films, onto the surface of the prints accelerated the degradation of the colorants, especially the yellow dye, in chromogenic materials. In the case of silver dye bleach materials, however, the opposite effect was observed. The influence of the material combination on the stability of face mounted color photographic prints was demonstrated to vary considerably. In order to better assess the inherent damage potential of the materials themselves, these were examined by means of instrumental analysis and measurements of pollutant gasses. Besides off-gassing compounds such as acetic acid and changes in pH caused by aging of the adhesive, face-mounting with a rigid plastic sheet (acrylic glazing) also affected the respective fading behavior of the various materials that were tested. 相似文献
10.
11.
《文物保护研究》2013,58(4):284-286
AbstractThe widespread occurrence of thecotrichite, Ca3(CH3COO)3Cl(NO3)2·7H2O, in the museum environment is explained theoretically by construction and examination of its phase diagram. Thecotrichite formation was simulated in the laboratory to identify the key factors involved in its production. This efflorescence occurs on porous limestone or calcareous artefacts such as pottery, stored in wooden cabinets that generate acetic acid vapour. Salt production depends on the moisture content of the object and the concentration of acetic acid in its surroundings. Furthermore, for thecotrichite to form the artefact must contain soluble chloride and nitrate salts. 相似文献
12.
《文物保护研究》2013,58(3):91-106
AbstractSaint Michael’s at Hildesheim, a Benedictine cloister church built in the eleventh century, was provided, towards the end of the twelfth century, with a painted ceiling consisting of oak boards. It represents the so-called ‘root of Jesse’, the genealogical tree of Jesus Christ. The ceiling, preserved in its original state except for a small part which was destroyed during the seventeenth century, was painted in lime-casein tempera. It was taken down in 1943 to protect it from destruction through air raids. It was restored in the years from 1955 to 1960. Later repaints were taken off and the original state regained. The pigments examined were identified as those known from the High Middle ,Ages, i.e. Lapis Lazuli, Orpiment, Natural Vermilion, Charcoal, Green Earth, Ochre, Verdigris as well as Lime White, which has been described by Cennini as ‘Bianco di San Giovanni’. Lead White has not been identified in any of the specimens analysed. 相似文献
13.
《文物保护研究》2013,58(4):289-303
AbstractA tube-type passive sampling method has been developed and assessed for the quantification of formaldehyde (methanal) vapours in indoor air. The sampler was designed for use in museums where test sites often include small enclosures with low air movement. The procedure involves collection of formaldehyde vapours in a Palmes diffusion tube containing a paper support impregnated with an acidified solution of 2,4-dinitrophenylhydrazine (2,4-DNPH). After sampling, quantification of the trapped F-DNPH is achieved by high performance liquid chromatography (HPLC) analysis with UV detection at 350nm. To validate the procedure, permeation devices were used to generate formaldehyde-containing atmospheres, 81–2975ppb, in a 20dm3 chamber so that experimentally derived sampling rates could be calculated and compared with the theoretical value. Three 2,4-DNPH solutions were investigated to obtain an efficient and stable trapping solution. Best results were achieved with a 27mg.ml?1 solution of 2,4-DNPH which contained 4·5%v/v orthophosphoric acid. At 55% RH, and with low airflow in the chamber, the experimentally derived sampling rate of 1·34 ± 0·17ml.min?1 was in good agreement with the theoretically derived sampling rate of 1·36ml.min?1 The passive sampling method was repeatable and reproducible with RSD (relative standard deviation) values below 7%for long-term exposures at low air velocities. 相似文献
14.
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
15.
《文物保护研究》2013,58(1):14-22
AbstractThe use of antioxidants to retard the yellowing rate of dammar varnish is investigated. A dammar formulation is given which should not significantly yellow in two to three hundred years of natural ageing. It is also shown that the choice of solvent when preparing a dammar varnish solution will affect yellowing rates of the resulting films. 相似文献
16.
Simona Raneri Jacopo Crezzini Simona Arrighi Francesco Boschin Ilaria Alfieri Germana Barone 《文物保护研究》2013,58(5):298-309
ABSTRACTThe surface texture of a stone represents a sensitive parameter in evaluating its conservation state. In monuments and sculptures, in fact, external agents continuously alter the appearance of stones, determining peculiar weathering patterns and modifying properties such as retention of water and particles, interaction with light, color, and finishing. The application of protective coatings also determines changes in surface appearance of a stone, usually evaluated and monitored by color change tests. Surface metrology methods offer the possibility to quantify these changes, evaluating the impact of external agents (natural, i.e. weathering, and artificially, i.e. protective coatings) on natural stones. In this research, we demonstrate the potential of surface areal measurements in describing the evolution of weathering processes and the effects of protective treatments on porous stone materials. The obtained results suggest that the extent of the modifications is related to the scale of observation (small- vs. large-scale undulations, i.e. roughness and waviness, respectively), with an overall increase of surface roughness as the weathering proceeds. Unexpectedly, coatings based on nanoparticle dispersions increase the topographic height parameters, due to the absence of a homogeneous film. 相似文献
17.
《文物保护研究》2013,58(3):150-155
AbstractThe treatment of two silver bangles found at Rojdi and dated c. 2000 b.c. is described. The bangles were separated by removing the hard incrustations with a 20% sodium hexametaphosphate solution and 15% acetic acid. Silver chloride was removed with a 25% solution of 0.88 ammonia and a 20% aqueous solution of ammonium thiosulphate.Silver sulphide was removed in a 20% formic acid bath. Polyvinyl acetate was used for consolidation, and a coating of polymethyl methacrylate was applied. The silver was found to contain copper and lead. The causes of embrittlement and the manufacturing technique are discussed. 相似文献
18.
《The Reference Librarian》2013,54(65):103-110
Summary The State Library of Delaware has brought DelAWARE: The Digital Library of the First State into being in regular, steady increments. Providing a digital library for a state library network, no matter how small, is always a project both blessed with support systems and fraught with unforeseen obstacles. You just never know what will happen next or who will show up to save the day. By steadfastly working and collaborating with all partners (librarians, vendors, state agencies), De/AWARE: The Digital Library of the First State is being brought into existence, a product at a time. By addressing the needs and difficulties of its users, the digital library grows into something uniquely useful for the state and its citizens. 相似文献
19.
《文物保护研究》2013,58(3):97-102
AbstractPrehistoric decorated caves, witness to man's artistic activity many thousands of years ago, have survived till now thanks to favourable conditions of conservation. Since their discovery, as a consequence of changes brought about by various developments and heavy visitor traffic, their precarious equilibrium has been threatened. Before we attempt to strengthen or to restore this state of equilibrium, it is desirable to understand the mechanisms governing the current in situ conditions in relation to the circulation of air, variations of humidity and temperature, the relationship between the cave and its surroundings, and the role of microorganisms. 相似文献
20.
《文物保护研究》2013,58(2):143-144
AbstractOil paints dry by polymerization. This 'drying' process may be substantially complete and the surface of the paint film dry to the touch within weeks, but measurable changes continue for years. Other, slower processes also continue, primarily hydrolysis of glyceride esters. This produces carboxylic acid groups as either free fatty acids (in the case of acid groups that have not reacted otherwise) or acid groups bound to the crosslinked oil matrix (in the case of acid groups that have engaged in polymerization reactions). These may react with pigments to form carboxylate salts (called soaps in the case of a fatty acid). These changes affect the physical properties of the paint and the way that conservation treatments affect it. This paper examines the extent of hydrolysis and soap formation in some naturally aged drying oil and paint films, the extractability of these materials in organic solvents, and measured and predicted changes over time in the physical properties of naturally aged paint films. Long-term physical and mechanical changes due to aging are minor compared to those produced by overcleaning or excessive exposure to heat. 相似文献