Browsing by Author "Marco, Alexandra"
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- As alterações da pintura mural a fresco no Norte de PortugalPublication . Marco, Alexandra; Vieira, Eduarda; Caetano, Joaquim I.; Pintado, M. E.; Moreira, Patrícia R.Apesar de grande parte do estudo da pintura mural a fresco estar por efectuar, esta expressão artística desenvolveu-se em Portugal com intensa actividade entre os séculos XV e XVI. No Norte de Portugal, devido a uma maior escassez da matéria-prima cal, a pintura apresenta frequentemente apenas uma camada de reboco, extremamente delgada, por oposição à usual utilização de duas camadas. O suporte destas pinturas foi quase exclusivamente o granito, uma rocha com boas propriedades fisico-químicas para a execução de revestimentos de cal e tipologias decorativas associadas. A degradação das pinturas murais, além da acção humana, está relacionada com a alta porosidade do substrato, sua natureza carbonatada, a presença de água nas paredes e as condições ambientais. A conjugação destes agentes é responsável pela perda significativa de área pictórica e das manchas negras inestéticas por biocolonização. No Norte de Portugal vários frescos dos séculos XV-XVI evidenciam esta alteração que mancha tanto os suportes como as pinturas – alteração de grande impacto estético que domina a atenção dos conservadores-restauradores na metodologia das intervenções. Apesar do substrato dos frescos ser principalmente inorgânico, o depósito de partículas atmosféricas e a absorção de água por capilaridade, pode promover o desenvolvimento de fungos, que segregam metabolitos como ácidos orgânicos. Diversos fungos também produzem pigmentos que variam em função da espécie, dos constituintes da pintura mural, dos factores ambientais, entre outros. O tratamento com biocidas é eficaz na erradicação dos organismos, mas não na remoção da pigmentação resultante do seu crescimento. Para assegurar intervenções éticas e sustentáveis, é fundamental conhecer tanto a natureza e comportamento dos materiais, como o seu estado de conservação actual e a identificação dos agentes e factores de degradação. Este trabalho pretende apresentar um estado da arte para este tema, incluindo os métodos mais comuns de abordagem em Conservação e Restauro para este problema.
- Application of micro-CT for the study of mural paintings - the case of São Tiago churchPublication . Marco, Alexandra; Campos, Bruno; Vieira, Eduarda; Pintado, Manuela; Moreira, Patrícia R.
- Basil essential oil as an alternative to commercial biocides against fungi associated with black stains in mural paintingPublication . Marco, Alexandra; Santos, Sandra; Caetano, Joaquim; Pintado, Manuela; Vieira, Eduarda; Moreira, Patrícia R.In northern Portugal it was identified that some mural paintings from the 15th and 16th centuries disclose a chromatic alteration in the form of black stains possibly of microbiological origin. In the search for its cause, samples were collected and microorganisms were isolated from selected areas of the pictorial sets of three case studies that displayed dark pigmentation. Four representative fungal isolates were selected due to their pigmentation and growth characteristics – Alternaria alternata, Alternaria tenuissima, TZ10.2.2 (possibly Pestaloptia sp.) and TZ8.2.2 (possibly Penicillium sp.). An attempt was made to encounter an innovative environmentally innocuous and green safe alternative biocide to replace the chemical-based toxic compounds currently in use. Essential oils with confirmed antifungal potential and seldom employed in the conservation of cultural heritage and even less in mural painting (Rosmarinus officinalis, Foeniculum vulgare, Citrus lemmon, Ocimum basilicum and Salvia officinalis), were tested against commercial biocides (Benzalkonium chloride, Preventol R80, CaSoPaL® and Durolith®), to evaluate their in vitro efficacy and the determination of the minimum inhibitory concentration. Basil was able to inhibit growth on all tested strains at 1.25 μl ml−1. From the commercial biocides, Benzalkonium chloride and Preventol R80 were the ones with the best performance but needed higher concentrations than basil to achieve the same result enabling this essential oil a useful alternative to commercial biocides. The literature regarding the use of essential oils in mural paintings is, apart from two known authors, practically non-existent making it a novel approach.
- Chemical characterization of black stains on mural paintings with granite support from churches of Northern PortugalPublication . Campos, Bruno; Marco, Alexandra; Valadas, Sara; Bobos, Iuliu; Vieira, Eduarda; Pintado, Manuela; Moreira, Patricia
- GIS technology for documentation of wall paintings in northern Portugal with a dark stain phenomenonPublication . Marco, Alexandra; Henriques, Frederico; Vieira, Eduarda; Pintado, Manuela; Moreira, Patrícia R.We often come across a problem of deterioration in some 15th and 16th century mural painting (MP) ensembles on the inner walls of granitic Romanesque religious buildings in the north of Portugal (fig. 1). It is manifested by the presence of dark pigmentation staining both granite supports and mural paintings (Marco, 2016 and 2019). The origin of this phenomenon is unknown and may be due to synergy of factors such as microbiological and chemical attacks.
- 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.
- Innovative biotechnology solutions for black stain removal and preventive conservation of historical and culturally important mural paintingsPublication . Marco, Alexandra; Vieira, Eduarda; Pintado, M. E.; Moreira, Patrícia R.
- 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.
- The shift of paradigm when religious art works became heritage: the dilemma of material vs immaterial significance : an overview of Portuguese reliquaries and mural paintingsPublication . Palmeirão, Joana; Marco, Alexandra; Carvalho, Salomé; Vieira, EduardaWe entered the twenty-first century with new perspectives on the concept, contents and meaning of “cultural heritage”. By changing the focus of conservation heritage from material to intangible aspects, the theoretical debate brought a new vision and new challenges on its conservation. The 1989 Code of Ethics of the Canadian Conservation Institute (CCI) defined “cultural property” as those objects having “cultural or religious significance” assuming their communicative function, as does the American Institute for Conservation (AIC). In this sense, the “objects” (and here we use the term defined by Barbara Applebaum) do not matter for what they are (materiality - historical or artistic truths), but for their meaning, and their usefulness and communicative functions. Thus, being the cause of the symbolic value attached to them by the subject(s). This clearly refers to the immaterial or intangible aspects of heritage (Muñoz Viñas, 2003). It tells us that the immaterial aspects should be incorporated in conservation issues. But how do we keep the intangible aspects of an object that, at a certain time of its life, lost their function and significance for which was produced? In this poster we dicuss the "patrimonialization" procesess of religious art (reliquaries and mural paintings) removed from the cult or even from religious spaces.
- The shift of paradigm when religious art works become heritage: the dilemma of material vs immaterial significance. An overview of portuguese reliquaries and mural paintingsPublication . Palmeirão, Joana; Marco, Alexandra; Carvalho, Salomé de; Vieira, EduardaThe 21st century introduced new perspectives on the contents and meaning of “cultural heritage”. By shifting the focus of conservation heritage from material to intangible aspects, the theoretical debate carried new approaches and challenges on its conservation. The 1989 CCI Code of Ethics defined “cultural property” as those objects having “cultural or religious significance” assuming their communicative function, as does the American Institute for Conservation (AIC). In this sense, “objects” (according to Barbara Applebaum’s interpretation) do not matter for what they are (materiality - historical or artistic truths), but for their meaning, their usefulness and communicative functions. This clearly refers to the immaterial or intangible aspects of heritage (Muñoz Viñas, 2003) and as immaterial values matter they should be incorporated in conservation issues. But how do we maintain the intangible issues of an object that, during its lifetime, lost their original function and significance?