1,721,073 research outputs found
How Can Ozone and Relative Humidity Affect Artists’ Alkyd Paints? A FT-IR and Py-GC/MS Systematic Study
Full text linkKnowledge of the chemical–physical reactions that determine the main degradation behaviour of artists’ alkyd paints represents one of the main problems within the museum exhibitions. The collection and interpretation of these data on degradation phenomena, especially after ozone exposure at different relative humidity values, can be useful for their conservation needs. Therefore, a systematic investigation of these materials may help achieve this goal. Firstly, surface-level identification of the main functional groups of ad hoc created and aged alkyd paints was performed using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). Subsequently, these paints were investigated by pyrolysis–gas chromatography and mass spectrometry (Py–GC/MS), allowing for precise bulk identification of the organic compounds before and after accelerated ageing. A first successful attempt to provide quantitative Py–GC/MS data on alkyd-based paints is here presented and discussed. Comparing the results, it was possible to obtain new insights into the degradation behaviour of alkyd paints when exposed to ozone, allowing us to devise specific preventive and conservation strategies for these artistic materials
TECNOLOGIE PER IL RISANAMENTO DELLE MURATURE DALL’UMIDITÀ DI RISALITA: STUDIO DELL’EFFICACIA DEL SISTEMA ELETTRO-OSMOTICO APPLICATO NEL NARTECE
No full textIn questo contributo presentiamo lo studio dell’efficacia di un sistema di deumidificazione basato sull’elettro-osmosi passiva, applicato
nel 1999 in una muratura del nartece della basilica di San Marco e monitorato fino al 2016. Nella parte introduttiva riportiamo una breve analisi sul problema dell’umidità di risalita di acqua di mare nelle murature veneziane, basata sullo studio ed elaborazione di dati presenti nella letteratura scientifica e riferiti a murature veneziane tradizionali in mattoni pieni. La basilica di San Marco, pur presentando una struttura differente rispetto alla maggior parte degli edifici veneziani, risente in maniera evidente dell’interazione con l’acqua della laguna e per questo rappresenta un esempio emblematico della complessa convivenza tra imateriali dell’architettura e l’ambiente lagunare. Lo studio dell’efficacia del metodo di deumidificazione applicato sulla muratura del nartece, oggetto di questo contributo, si basa su dati sperimentali ottenuti nel corso del tempo ed evidenzia la complessità del fenomeno della risalita capillare in un ambiente in continua evoluzione e in una struttura così particolare come quella della basilica. Questo insieme di complessità e unicità sottolinea l’importanza del monitoraggio inteso come attenzione non solo verso la muratura, ma anche verso le condizioni ambientali circostanti e le relative mutazion
Torcello e la morfologia della laguna tra l'età romana e il medioevo
No full textRevisione delle conoscenze sull'evoluzione geomorfologica del settore settentrionale della laguna di Venezia nel corso degli ultimi due millenni, in relazione alle variazioni fluviali e della linea di costa
Tiles from Aosta: A Peculiar Glaze Roof Covering
Full text linkThe 18th century roof tiles from the “Casa delle vigne”, located in the Aosta region (north-east Italy), were investigated as an example of a peculiar historical roof covering: ceramic tiles with a lead-based glaze finishing to waterproof them are used to create colourful patterns. A conservation project proposed the integration of the original tiles with new ones, produced according to traditional methods. Ancient and new tiles were analysed with Fiber Optics Reflectance Spectroscopy, micro-Raman, Fourier Transform Infrared Spectroscopy and X-ray Fluorescence Spectrometry, Thermogravimetry and Differential Scanning Calorimetry for understanding the composition and the production technology of this manufacture. Their resistance to freezing and thawing cycles was then tested, considering their exposure in the severe alpine climate of Aosta. The use of pure clays with low calcium contents, high firing temperature and lead-rich glazes was found in ancient tiles, able to outstand several freezing-thawing cycles without damages. Iron and copper pigments were used in old yellow and green glazes. Zinc-based pigment, low lead and calcium-rich glazes are used in the new ones, which remained mainly coherent to the ceramic body during the freeze-thaw test
A new methodology to characterize indoor variations of temperature and relative humidity in historical museum buildings for conservation purposes
No full textThis paper presents the study of the indoor climate of the Scuola Grande di San Rocco in Venice: it is a 16th-century emblematic example of a historical building. The renowned Tintoretto large paintings magnificently decorate the Scuola. The monitoring and control of microclimatic parameters such as Temperature (T) and Relative Humidity (RH) are pivotal to establish proper conservation policies in museums’ environments. Fragile artworks had been preserved for centuries in “natural climate” conditions, in the framework of historical buildings. In such ambiances, T and RH followed outdoor variations yet mitigated by the hygrothermal inertia of the building. Available indoor climate monitoring protocols consider T and/or RH values, but they do not allow a straightforward comparison of relative fluctuation of T and RH values through time. This paper presents a flexible methodology to visualize T and RH variations. The protocol considers the calculation of time-related index to understand the magnitude of daily (DF) or weekly fluctuations (WF), and the speed of the weekly fluctuations (SWF). The presented method introduces the calculation of climatic excursions index (ICE). The ICE is innovative because it allows us to compare the microclimate of different buildings, and it will enable us to quantify the time in which T and/or RH fluctuate outside reference ranges, even in the case that detailed information on materials and construction methods is lacking. Indoor microclimate variations have been compared with the outdoor ones: this helps to define the hygrothermal inertia of the building
Proposal of New Natural Hydraulic Lime-Based Mortars for the Conservation of Historical Buildings
Full text linkNHL mortars are known to be compatible materials for the conservation of architectural heritage. To improve their properties with regard to salt resistance and lower their carbon footprint, NHL-based mortars with salt inhibitor agents were studied and different formulations were produced: NHL-based mortars (MSs), composed of natural hydraulic lime; and sand and cocciopesto mortars (MSCs), in which NHL, sand and brick powder were admixed with two different products, diethylenetriaminapenta and chitosan, in different concentrations. The mortar performance was tested against freeze–thaw and salt crystallization through immersion–drying cycles in a 14% sodium sulfate solution. The results highlighted that the addition of cocciopesto was effective in increasing the salt resistance, but increased the water intake during the freeze–thaw tests. The use of DTPMP produced less thixotropic mortars and decreased the water uptake, but worsened the salt resistance of hardened mortars. Chitosan allowed a good workability of fresh mortar; its water uptake was similar to the reference mortar and slightly increased the salt resistance. In the cocciopesto samples, both additives reduced the weight variation during freeze–thaw tests; meanwhile, for the lime samples, the additives increased the weight variation during the final cycles
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