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- Bylund Melin, Charlotta, et al.
(författare)
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Moisture gradients in wood subjected to relative humidity and temperatures simulating indoor climate variations as found in museums and historic buildings
- 2017
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Ingår i: Journal of Cultural Heritage. - : Elsevier BV. - 1296-2074. ; 25, s. 157-162
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Tidskriftsartikel (refereegranskat)abstract
- Climate-induced mechanical damage to cultural heritage objects of hygroscopic materials is not yet fully understood. This is particularly true of objects in historic buildings with less climate-controlled indoor environments. Research aiming at clarifying the response of hygroscopic materials to changes of the ambient relative humidity and temperature is scarce. The objective of this study was to use a method to monitor relative humidity and temperature at three different depths inside samples of Scots pine (Pinus sylvestris L.), subjected to relative humidity and temperature fluctuations in a climate chamber. This approach is important because mechanical stress is related to the moisture content of the material. However, the knowledge on how moisture gradients in wood progress before reaching equilibrium has not been studied in depth in cultural heritage science. The monitored relative humidity and temperature data in the wooden samples were converted to moisture content using a method that took both temperature and the hysteresis effect into account. The samples were subjected to step changes and daily relative humidity fluctuations at different temperatures. Moreover, museum climate, a non-heated historic building climate, and intermittent heating of a typical church were simulated in the experiments. Low temperatures reduced the moisture diffusion rate, resulting in moisture content fluctuations of smaller amplitudes. A response delay was noted which gradually increased with depth in the wood and with low temperatures. A combination of a step-change and daily fluctuations increased the time to reach equilibrium due to the slower desorption process compared to adsorption process. Occasionally, the moisture content could also exceed equilibrium at some depths. The moisture content levels in wood during intermittent heating stayed stable overall. The conclusion is that moisture transport in wood is complex and is influenced by the moisture history of wood, as well as duration and amplitude of the combined fluctuations in relative humidity and temperature. (C) 2016 Elsevier Masson SAS. All rights reserved.
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- Bylund Melin, Charlotta, et al.
(författare)
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Monitoring Dynamic Moisture Gradients in Wood using Inserted Relative Humidity and Temperature Sensors
- 2016
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Ingår i: e-Preservation Science. - 1854-3928. ; 13, s. 7-14
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Tidskriftsartikel (refereegranskat)abstract
- To be able to combine the preservation of wooden objects of cultural significance with energy efficiency measures it is important to develop our knowledge of the relation between the rate of change of relative humidity and temperature, moisture content gradients and the resulting dimensional change of wood. The work presented here introduces and evaluates a method for monitoring dynamic moisture content gradients, mainly for research applications. Relative humidity and temperature were measured by miniature sensors, placed in drilled holes at different depths in wood samples to monitor the moisture transport. The data was used to calculate moisture content and the results could hence be compared with the results from a commercial resistance moisture meter, monitored at the same depths. The results of the two methods did not coincide. A Fickian model for moisture diffusion was chosen to verify the monitored results. It showed poor fit with the commercial resistance method and a reasonably good fit with the new method using relative humidity and temperature sensors. We concluded that the new method provides reliable and consistent data suitable for monitoring moisture content at different depths under unsteady state conditions, while the data generated by the resistance method in our set-up was inconsistent with the model and with our understanding of the moisture transport process.
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- Bylund Melin, Charlotta, et al.
(författare)
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Monitoring Dynamic Moisture Gradients in Wood using Inserted Relative Humidity and Temperature Sensors
- 2016
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Ingår i: e-Preservation Science. - 1581-9280. ; 13, s. 7-14
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Tidskriftsartikel (refereegranskat)abstract
- To be able to combine the preservation of wooden objects of culturalsignificance with energy efficiency measures it is important to developour knowledge of the relation between the rate of change of relativehumidity and temperature, moisture content gradients and the resultingdimensional change of wood. The work presented here introduces andevaluates a method for monitoring dynamic moisture content gradients,mainly for research applications. Relative humidity and temperaturewere measured by miniature sensors, placed in drilled holes at differentdepths in wood samples to monitor the moisture transport. The data wasused to calculate moisture content and the results could hence be comparedwith the results from a commercial resistance moisture meter,monitored at the same depths. The results of the two methods did notcoincide. A Fickian model for moisture diffusion was chosen to verify themonitored results. It showed poor fit with the commercial resistancemethod and a reasonably good fit with the new method using relativehumidity and temperature sensors. We concluded that the new methodprovides reliable and consistent data suitable for monitoring moisturecontent at different depths under unsteady state conditions, while thedata generated by the resistance method in our set-up was inconsistentwith the model and with our understanding of the moisture transportprocess.
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- Bylund Melin, Charlotta, et al.
(författare)
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Painted wood as a climate indicator?-Experiences from a condition survey of painted wooden panels and climate monitoring in Läckö castle, a dehumidified historic building
- 2010
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Ingår i: Multidisciplinary Conservation:a Holistic View for Historic Interiors. Proceedings from the Joint Interim-Meeting of five ICOM-CC Working Groups, Rome 23-26 March 2010 (eds: Elsje Janssen, Mariabianca Paris, Malgorzata Sawicki, Kate Seymour, and Andrew Thorn).
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Konferensbidrag (refereegranskat)abstract
- Läckö Castle is an historic building that has never been permanently heated but has been dehumidified since the early 2000s to house museum collections. The purpose of the work was to evaluate the dehumidification performance and compare the climate with the state of preservation of wooden wall paintings. Compiled climate recordings for different rooms in the castle from 1997 to 2009, before and during dehumidification, were used and compared to the outside climate. The RH set point value of 70 % for dehumidification was not reached often, especially in winter with high outside RH. Wood painted with a linseed oil paint performed well, whereas paint containing resin was seriously damaged. It is concluded that microclimatic differences in relation to dominating wind direction are important. The air exchange of the building is very decisive for dehumidification efficiency.
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