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1.
ABSTRACT

The impact of relative humidity (RH) and temperature variation on the mechanical behaviour of paintings on canvas was investigated, based on the various environmental recommendations that are applied by museums and institutions worldwide. Paint samples were constructed based on the works of twentieth-century artists such as Soulages and Riopelle. The various samples are based on criteria such as paint media, additives, pigment type, canvas type, thickness, type of application, and drying time. Once they are fully dry, paint films behave as elastic, viscoelastic, or viscoplastic materials depending on the chemical nature of their components. These properties, as well as tensile strength, were determined by a series of tensile tests. Other samples were included, originating from discarded oil paintings on canvas from the seventeenth and nineteenth centuries. To carry out mechanical tests under controlled conditions of temperature and RH, a climatic chamber was built around the column of a universal testing machine. Samples were submitted to stress relaxation tests to observe their response to changes in environmental conditions. RH was increased from 20 to 90% and temperature from 15 to 60°C. Reactivity diagrams were drawn based on the results. The endurance limit under mechanical fatigue was determined from the diagrams and helped define the risks associated with each painting type when exposed to the accepted environmental recommendations.  相似文献   

2.
《文物保护研究》2013,58(4):229-240
Abstract

This paper describes a novel technique to stabilize the relative humidity (RH) of the air inside museum showcases by using a synthetic hydrophobic membrane coupled with a hygroscopic solution in a membrane contactor. RH-monitoring data for two identical test cases, one of them controlled by a set-up with a plane-plate membrane contactor crossed by forced air and lithium chloride (LiCl) solution flows, show a significant stabilizing effect on RH fluctuations. A theoretical model permits forecasts in close agreement with the experimental RH data. Further calculations carried out over a one-year period show that notable damping of external RH variations can be obtained by using a low air circulation rate, small membrane surface area and low solution mass per unit case volume. A more general analytical solution in harmonic conditions is derived and discussed.  相似文献   

3.
《文物保护研究》2013,58(2):104-112
Abstract

An exhibition case displaying ancient bronzes was found to have a high leak-rate and was subject to a variety of environmental factors. Because of the original case design, passive means of control were not proving effective. A simple, low-output (below 28l.min?1) drying system based on hollow fibre (polysulfone) technology was tested and installed in the case to maintain the microenvironment below 43% relative humidity (RH). The membrane was tested below industrially-specified pressure parameters (less than 4 bar) and found to produce a range of consistent RH outputs suited to museum use. After some years in service, the system has proved reliable and simple to operate; optimum performance was achieved with more continuous operation.  相似文献   

4.
《文物保护研究》2013,58(1):8-17
Abstract

Absorbent materials such as wood, paper and cotton stabilize the atmosphere of show-cases against the relative humidity changes caused by temperature variation and by exchange of air with the surroundings.

There are several exchange processes between the air in the case and the outside air: diffusion through porous COllstruction materials, air flow caused by temperature and pressure changes and airflow by convection in a show-case whose relative humidity differsfrom that of its environment. The air changes about once a day in show-cases made by conventional joinery techniques. The rate of exchange can be reduced to less than five volumes a year by sealing a show-case so that only one small hole is left for pressure equalization. A dust and sulphur dioxide filter can then be fitted to maintain a pure atmosphere within.

In heated rooms without air-conditioning the RH may fall dangerously low in winter. A static method of RH control for a show-case is described. This is a saturated solution of sodium bromide covered by a silicone rubber membrane.  相似文献   

5.
ABSTRACT

This study examined the impact of relative humidity (RH) on the corrosion rate of 129 archaeological iron nails from two sites. Oxygen consumption of individual nails in controlled RH was used as a corrosion rate proxy to deliver quantitative data on corrosion rate as a function of RH. This was negligible at 20% RH, slow up to 40% RH for both sites, and increased rapidly at 60% RH for Roman nails from Caerleon (Wales) and at 70% RH for medieval nails from Billingsgate (London). The nails were digested and their chloride content was determined and related to their oxygen consumption at specific RH values. While a generic pattern of corrosion as a function of chloride was identified, for any single concentration of chloride corrosion rate was not predictable. Desiccation is in common use to control post-excavation corrosion of archaeological iron; quantifying how differing levels of desiccation changed corrosion rate provided a scaled tool for identifying corrosion risk, estimating object longevity, and calculating cost benefit for storage options.  相似文献   

6.
《文物保护研究》2013,58(2):88-94
Abstract

This paper examines the impact of relative humidity on jades by enclosing the samples under constant relative humidity (RH) of 32, 49, 61.5, and 81.7% at the same temperature of 40 ± 0.1°C for 160 days. The simulated samples were pure and dense tremolite jade and serpentine jade, impure tremolite jade and serpentine jade containing some calcite, and serpentinized calcite, which are all common materials of ancient jade found in archaeological excavations. All samples were characterized through particle-induced X-ray emission and a glossmeter. The degree of deterioration proved to be greater in impure materials than in pure ones. The best RH to conserve various kinds of materials differs: for pure tremolite and serpentine, all of the RH levels are equal; for impure tremolite with some calcite, 61.5 and 81.7% were superior; for impure serpentine with some calcite, the highest RH (81.7%) was best; and as to the serpentinized calcite, there is no clear conclusion as yet and further research is needed.  相似文献   

7.
《文物保护研究》2012,57(1):14-27
ABSTRACT

Zinc (carboxylate) soaps, formed by reactions between zinc oxide (ZnO) and fatty acids in a drying oil, are known to cause deterioration in the paint layers of modern and contemporary oil paintings. This study investigates zinc carboxylates that developed in an oil painting test panel designed to mimic the aging and degradation encountered in actual works of art. Following accelerated and natural aging, protrusions were noted on the surface of the test panel. A large protrusion with erupted gel features was extracted from the test panel, mounted in top view, and then cut to reveal the sample's cross section. The gel features, which resulted from the unreacted oil binder's separation from the paint matrix, facilitated zinc carboxylate formation. Using reflectance µ-FTIR and SEM-EDX analysis, the morphologies and spatial distributions of zinc carboxylates within the gel regions of the protrusion were studied. A concentration gradient of zinc within the gel material was observed in the cross-sectional view, indicating patterns of zinc carboxylate formation and migration.  相似文献   

8.
ABSTRACT

Control of relative humidity (RH) for collections care is challenging in U.K. historic houses because they are often highly ventilated with poor heat retention, a porous building fabric and naturally tend to high (60–80%) RH if unheated. The significance of the building means that large-scale modifications and installation of air handling systems may be unfeasible and undesirable for the conservation of the building. In the late 1980s the National Trust, for English, Wales and Northern Ireland, investigated conservation heating as an RH control method that works with the natural environment of historic buildings, mimicking historic heating and requiring only modification of existing heating services or a light touch installation of new heating systems. The National Trust adopted conservation heating as its preferred method for environmental control in historic buildings from the 1990s. This method was presented at the IIC 1994 Ottawa congress on preventive conservation. Conservation heating has since been adopted by many historic house management organisations, particularly across north-west Europe, where it is well suited to the climate. This paper reviews conservation heating developments implemented by the National Trust since 1994, in response to a changing external context, new knowledge and developments in operational practice.  相似文献   

9.
ABSTRACT

Many museums are housed in historic buildings, sometimes the building itself is part of the museum collection. Creating a stable environment by providing a nearly constant temperature and relative humidity at correct levels decreases the risk of object degradation. Maintaining this steady indoor environment, however, increases energy consumption and risks to the historic building. Museum display cases offer a solution to the mitigation of risks to which valuable objects may be subjected by providing an extra layer of protection to indoor climate fluctuations. The Anne Frank House is a historic house museum located in Amsterdam. The museum has undergone several renovations in the last years to deal with an increase in the number of visitors to over 1.2 million a year. The original diaries and other documents of Anne Frank are permanently on display in the Anne Frank House. With the recent refurbishment the possibility arose to design a new state-of-the-art display case. This study presents the results of the experimental research related to the design, performed in-situ. The temperature and relative humidity in the new exhibition space and inside the new display cases were monitored to gain insight into the hygrothermal behavior of these controlled environments. A complementary numerical study was performed to investigate effects of dynamic climate control of the exhibition gallery and climate conditions in the display case under various circumstances. Four main conclusions are presented in this paper. The investigated display case design is able to provide a stable relative humidity environment by means of silica gel, while using an active box-in-box climate control system to create stable temperature conditions. The inner case temperature depends on the temperature supplied by the display case air handling unit. Protocols must be in place in case of malfunction or failure of the climate control system of the display case. The air handling unit of the case needs to be shut off to create a passive environment for the objects on display until necessary actions are taken. Exhibition gallery set points can be less stringent when susceptible museum objects are on display in the display case. The environments are separated and provide an opportunity for energy saving set point strategies. The last conclusion drawn is that the numerical study provides valuable insight into imposing dynamic control of set points for temperature and relative humidity in the exhibition gallery and the effect on the display case environment.  相似文献   

10.
ABSTRACT

Historic buildings in Denmark have a high relative humidity (RH) all year, so the interiors are exposed to biological degradation. The acceptable range for RH is 60–70%, which is higher than the usual recommendations for museums and galleries. There are two options for humidity control: conservation heating or mechanical dehumidification. Calculation of the energy performance of a generic building was used to determine which method is the most efficient. Studies of a cottage in Liselund Park, and of two medieval churches in Hellerup and Vemb have confirmed these predictions: dehumidification is less energy consuming than conservation heating in buildings with poor thermal insulation and a moderate air infiltration rate (AER?<?0.6?h?1). Dehumidification is suitable for historic buildings, where heating is not needed for human comfort. A condensing dehumidifier uses less than half the energy per kg water compared to an absorption dehumidifier. But it does not work at temperatures below 2°C. The combination of a condensing dehumidifier and a little heating to prevent frost is the most energy efficient solution for humidity control. These results are only valid in mild and humid climatic conditions similar to Denmark.  相似文献   

11.
《文物保护研究》2013,58(4):251-268
Abstract

Extensive investigations of the deterioration of the romanesque painted wooden ceiling in the church of Saint Martin in Zillis (Switzerland) have revealed three major active deterioration phenomena: (1) tented flaking of paint layers; (2) flaking of the wheat starch fixative together with parts of the paint layer; and (3) fungal growth. These deterioration processes correlate with the dynamics of the prevailing room climate. Both forms of flaking are mainly driven by fluctuations of the relative humidity (RH), whereas the fungal attack can be related to high average RH and stagnant air. Frequent daily fluctuations in RH of up to 20% in summer are due to visitors leaving the doors open, while fluctuations of up to 25% are related to heating in winter. Given the risks of new consolidation treatments, the aim is to slow the decay processes by influencing the climate in the room. Installation of automatic door-closers reduced fluctuations but led to a rise in RH and a reduction of air movement, causing greater fungal growth. Subsequently, an automatic air-exchange system triggered by absolute humidity values was installed to reduce excess humidity and to exchange stale air without producing major fluctuations in the relative humidity. This kind of 'climatisation' has the advantage of being highly flexible, allowing variation of the rate and scale of exchange; it is, moreover, truly reversible.  相似文献   

12.
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   

13.
This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.  相似文献   

14.
CORRESPONDENCE     
none 《文物保护研究》2013,58(1):45-47
Abstract

The dendrochronological method for dating wood was specifically modified and applied for the first time to the age determination of oak panels of 17th-century paintings. It is now possible to give to the art historian an exact terminus post because of the determination of the time at which the tree was felled to be used in the manufacture of a panel. Results of extensive comparative studies and considerations of the method of manufacture of such panels often lead to an objective chronological determination of the period of creation of the painting. However, it is only possible to date a painting in this way; the authenticity of the artist cannot be established. Potential contradictions between the results of dendrochronological dating and style criticism must be resolved by the art historian.  相似文献   

15.
Conditions of relative humidity (RH) and temperature within museums and buildings holding collections of cultural heritage objects are often maintained around a strictly controlled set point of about 50 ± 5% RH and 20 or 21 ± 2°C to provide safe, stable conditions for hygroscopic artifacts. It has recently been proposed that these ranges should be relaxed to values that are less energy-intensive to maintain while still being safe for the objects in the collection, with the aim of reducing both carbon footprint and energy use. It is also suggested that conditions should be determined by the needs of individual objects and by the local climate of the region, rather than applying overall values across the museum as a whole. This proposal has led to much discussion within the conservation community. The suggested values, a stable humidity within the range 40–60% RH and a stable temperature within the range 16–25°C for most objects, apart from the most vulnerable, are derived from the results of experimental research on the responses of individual materials to particular conditions of RH and temperature, as well as observations of the behaviour of cultural heritage objects in their own environments and on loan. This paper describes briefly the historical and scientific background to the present discussion.  相似文献   

16.
《文物保护研究》2013,58(2):78-86
Abstract

Sensing devices used in museums for measuring relative humidity can be affected by pressure errors at altitudes over 900 m. The various instruments available for RH measurement are reviewed; an explanation of the pressure error is given and its significance for museums is evaluated; and information on avoidance of and correction for pressure errors is provided.  相似文献   

17.
ABSTRACT

The preservation of artefacts in museum collections is profoundly affected by fluctuations in temperature and, especially, relative humidity (RH). Since the late nineteenth century, many studies have been carried out on the best way to control hygrothermal conditions. In old buildings located in maritime temperate climate zones (such as Portugal) with strong thermal inertia, and which have low ventilation rate (relative to the volume and number of visitors), daily and seasonal hygroscopic inertia may help to assure the maintenance of RH stabilization conditions. The use of expensive active systems may be minimized through the passive behaviour of internal finishing building materials. This work presents the results of an experimental laboratory study conducted in a flow chamber to demonstrate the enormous potential of hygroscopic materials in stabilizing interior relative humidity. Based in these results and in-situ monitoring in a museum housed in a building, located in Porto, with a typical construction of the 1950s (granite masonry and reinforced concrete slabs), a numerical analysis was done to quantify the influence of hygroscopic materials in stabilizing the interior relative humidity.  相似文献   

18.
《文物保护研究》2013,58(2):103-109
Abstract

A prototype inspection system has been tested which makes use of electronic speckle pattern interferometry with computer image processing, for deformation and stress analysis and for the location and analysis of defects in museum objects. Two different examples have been chosen: a nineteenth-century oil painting on a wood panel and a seventeenth-century enamelled terracotta vase. The method can give quite accurate metrological information; it is also particularly promising for rapid qualitative analysis.  相似文献   

19.
ABSTRACT

Glass is often seen as a relatively stable material, unaffected by changes in environmental conditions, but recent studies indicate otherwise. Research on the atmospheric deterioration of glass has consistently shown a strong correlation between climate, especially relative humidity (RH), and the rate of deterioration. New studies by the authors have shown that even stable compositions are at risk, when the glasses are exposed to continuous broad fluctuations in RH and temperature. Letting standards slip for the long-term storage of glass can be devastating, eventually leading to irreversible damage that in the final stages can result in the complete destruction of an object. Current research and monitoring of collections at the Corning Museum of Glass indicates that the RH should be within the range of 40–50%. For already crizzled glasses, a tighter control to 40–42% is recommended. Analysis of compositions of already crizzled glasses is ongoing, and hopefully will lead to the identification of at least some groups of glasses that are more at risk. This will help in providing future environmental recommendations for identifiable compositions, selected glass types, or known manufacturers.  相似文献   

20.
ABSTRACT

In the Mogao Grottoes of Dunhuang, China, the ambient relative humidity (RH) fluctuation in the caves is the main cause for the deterioration that has been observed, especially the deterioration of the earthen plaster and wall paintings linked to the presence of NaCl and Na2SO4 salt contaminants. To help identify the mechanism responsible for this salt-related deterioration and provide a theoretical basis for the development of a preventive conservation regime, this study addressed the basic moisture adsorption mechanisms of earthen plaster with soluble salts by taking an experimental approach. It is shown that, as ambient RH increases, the moisture adsorption process of the plaster containing the soluble salts can be regarded to have three basic stages, as evidenced by the results of the moisture adsorption tests performed on earthen plaster samples with different NaCl or Na2SO4 contents at various humidity levels. The moisture adsorption mechanism and its determining factors at each stage are also analysed. In addition, it is suggested that the hygroscopicity of the plaster structure and the interaction between the different kinds of salts in the plaster, which makes the dissolution or hydration of the salt in the plaster pores much easier, should be considered more seriously regarding increases in the ambient RH in the caves.  相似文献   

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