Browsing by Author "Freire-Lista, David M."
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- Building granite characterisation, construction phases, mason’s marks and glyptography of Nossa Senhora de Guadalupe Church, Mouçós e Lamares, Galicia-North Portugal EuroregionPublication . Freire-Lista, David M.; Campos, Bruno B.; Moreira, Patrícia; Ramil, Alberto; López, Ana J.The Romanesque church of Nossa Senhora de Guadalupe of Mouçós e Lamares is located in Vila Real (North of Portugal). The exterior part of its nave is preserved almost unaltered. Most of the granite ashlars and corbels that make up this church have a mason’s mark in the centre of their faces. The building granites (Sanguinhedo and Vale das Gatas) have been identified and characterised petrographically and petrophysically. The mason’s marks have been as well identified; all the ashlars with visible mason’s marks have been mapped, and a glyptographic study has been carried out. In addition, the surface roughness of ashlars was measured. All these analyses have made it possible to locate the main historical quarry, to calculate the number of stonemasons who worked in the construction of the church, and to determine its construction phases. There are eight main types of mason’s marks on the nave façades. The quarrymen extracted the main building granite (Sanguinhedo granite) from the same quarry, or from nearby quarries. Although the most experienced stonemason has been identified, most stonemasons worked as a team during all construction phases of the church. Techniques such as petrography, ultrasonic P wave velocity, colourimetry, roughness and the determination of hydric properties will guarantee the quality and durability of the heritage stone for restorations. In addition, the glyptographic analysis revealed important historical and ethnographic findings that will be very useful for the appreciation of the monument. Therefore, the knowledge of built heritage, such as mason’s marks contribute to the conservation of historical quarries and traditions, as well as help understand the close cultural association societies have had with heritage stones. In this way, the scientific corpus of historical-cultural heritage can face for the development of tourism in Galicia-North Portugal Euroregion in a long-lasting sustainable way.
- Green chitosan: thiourea dioxide cleaning gel for manganese stains on granite and glass substratesPublication . Campos, Bruno; Marco, Alexandra; Cadeco, Guilhermina; Freire-Lista, David M.; Silvestre-Albero, Joaquin; Algarra, Manuel; Vieira, Eduarda; Pintado, Manuela; Moreira, PatríciaThe cleaning or removal of manganese stains on Cultural Heritage has not been much tested or successful so far. The aim of this article was to assess a new green cleaning gel for Mn-rich black-blue stains on different substrates. The black-blue stains were characterized at optical and chemical level through colour-related data, optical microscope, FTIR, XRF and XPS. Mn-stained granite found on historical churches at Vila Real (North of Portugal) and glass jars of Leclanché cells, belonging to the ISEP’s Museum (Portugal) collection, were the ideal case studies to test the efficiency of chitosan: thiourea dioxide (TD) cleaning gel. TD proved to be the best candidate to reduce insoluble manganese oxides, over Hydroxylamine Hydrochloride and Hydroxymethanesulfinic Acid. Cleaning assays performed on stained granite samples collected at a historical quarry and in situ application on stained granite churches allowed removal of the stains to a satisfactory level. Similar results were obtained on stained glass jars.
- Rare biogeochemical phenomenon associated to manganese patinas on mural painting and granite ashlarsPublication . Campos, Bruno; Marco, Alexandra; Freire-Lista, David M.; Durães, Nuno; Silvestre-Albero, Joaquin; Silva, Eduardo Ferreira da; Vieira, Eduarda; Pintado, Manuela; Moreira, Patrícia R.This article discloses a rare and outstanding type of Mn-rich black-blue patina found on mural painting and granite ashlars located in the church of Sta. Marinha, north of Portugal, and conjectures the phenomenon associated to the appearance of such patinas in different surface materials. This Mn-patina reported on mural painting and their origin is probably assigned to manganese leaching from building materials (i.e., granite and phyllites). Stained mural painting and granite examined by XPS and SEM have showed patinas enriched with manganese (IV) oxide, potentially catalysed by a microbiota, like fungi, observed in SEM micrographs. The pigments used to depict mural painting and groundwater were also analysed by micro-Raman and ICP-MS, respectively, indicating that they are unlikely manganese sources. Unstained building materials, such as granite ashlars, historic joints, mortars and phyllite rocks, were also analysed by ICP-MS showing that historic joints and mortars present significant concentrations of manganese, possibly associated to their absorbing feature. The main materials with potential to impart manganese to Mn-rich patinas are granite ashlars and phyllites. The aim of this investigation is to reveal and ascertain the hypothetical sources and the phenomenon responsible for the Mn-rich black-blue patina appearance, both on mural painting and granite ashlars.