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A exploração de enzimas na limpeza da pintura milagre da bilocação de Santo António
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Abstract(s)
As enzimas são moléculas biológicas de natureza proteica que funcionam como catalisadoras de reações químicas. Na conservação e restauro, têm sido utilizadas na limpeza de sujidades e na remoção de camadas de proteção alteradas, com resultados positivos. Diante dessa perspetiva, investigou-se a viabilidade de uma abordagem mais green para a limpeza de uma pintura. A obra que serviu de suporte para a investigação é uma pintura a óleo sobre tela do séc. XVII intitulada “Santo António livrando o pai da forca”, um dos milagres de bilocação deste santo. De autoria desconhecida, apresenta patologias que se alinham com casos de estudo em que o uso de enzimas mostrou bons resultados. Uma parte desta investigação inclui um levantamento do historial e proveniência da obra, que se encontrava numa capela privada em Torre de Moncorvo e que Vítor Serrão julga ser do extinto convento de S. Francisco, existente na mesma localidade. No tardoz da pintura identificaram-se uma inscrição e um desenho a carvão os quais foram devidamente analisados. A pintura dá entrada no Museu do Douro em 2023, no âmbito do projeto “Identificar para Conservar”, que visa preservar bens culturais em risco de preservação, na região demarcada do Douro. A pintura tinha inúmeras áreas de repinte e duas camadas de proteção muito alteradas e aplicadas em momentos diferentes. A mais recente revestia vestígios de uma mais antiga, que não terá sido totalmente eliminada, provavelmente por dificuldades na sua remoção. Os resultados de FTIR evidenciaram misturas complexas nestas camadas, sugerindo a presença de uma resina natural no verniz mais antigo e uma resina acrílica e cera, no verniz mais recente. As camadas cromáticas verdes encontravam-se totalmente repintadas com tinta a óleo e terá havido uma tentativa de limpeza incompleta que tornou essa áreas muito manchadas/irregulares. O objetivo do trabalho foi testar as enzimas na remoção destas camadas e ensaiar o seu uso em conjunto com hidrogéis de PVA-B. Foram testadas várias formulações de soluções enzimáticas, como o kit enzimático, o sabão enzimático e soluções tamponadas gelificadas. Procurou-se desenvolver um protocolo específico para avaliar a eficácia da limpeza com o objetivo de compreender os mecanismos de interação entre as enzimas e os diferentes meios testados, avaliando a sua forma de atuação, a sua eficácia e limitações. Essa abordagem permitiu uma comparação fundamentada permitindo um método sistemático e replicável. Diferentes formulações de PVA-B combinadas com solventes foram testadas para abordar problemas na obra que não puderam ser resolvidos pelo uso de enzimas, como a remoção de repintes e a devolução de leitura em todas as áreas com camadas de tinta verde na pintura.
Enzymes are biological molecules of a protein nature that act as catalysts for chemical reactions. In the field of conservation and restoration, they have been used for cleaning dirt and removing altered protective layers, achieving highly positive results. From this perspective, the viability of applying a “green” methodology to clean a painting was investigated. The artwork used as the basis for this research is a 17th century oil painting on canvas titled “St. Anthony saving the father from the gallows”, one of the saints’ bilocation miracles. Of unknown authorship, the painting presents pathologies aligned with case studies where the use of enzymes shown promising results. Part of this investigation involved examining the painting’s history and provenance. It was originally located in a private chapel in Torre de Moncorvo and Vitor Serrão believes it may have come from the now-defunct Convent of St. Francis in the same town. On the reverse side of the painting, an inscription and drawing of charcoal were identified and thoroughly analysed. The painting entered the Douro Museum in 2023 as part of the project “Identify to Conserve”, which aims to preserve cultural heritage at risk in the Douro Demarcated Region. The painting exhibited numerous overpainted areas and two heavily altered protective layers applied at different times. The most recent layer covered remnants of an older one, which likely had not been fully removed due to the challenges involved. FTIR analyses revealed complex mixtures in these layers, suggesting the presence of natural resin in the older varnish and a combination of acrylic resin and wax in the more recent one. The green paint layers were completely overpainted with oil paint, and an incomplete cleaning attempt had left these areas heavily stained and uneven. The aim of the project was to test enzymes for removing these layers and explore their use in combination with PVA-B hydrogels. Various formulations of enzymatic solutions were tested, including enzyme kits, enzymatic soap, and buffered gelled solutions. A specific protocol was developed to evaluate the effectiveness of cleaning, aiming to understand the mechanisms of interaction between the enzymes and the different tested media, assessing their functionality, efficiency, and limitations. This approach allowed for a systematic and replicable comparison. Different formulations of PVA-B combined with solvents were tested to address issues that could not be resolved with enzymes alone, such as the removal of overpaints and restoring the readability of all areas with green paint layers.
Enzymes are biological molecules of a protein nature that act as catalysts for chemical reactions. In the field of conservation and restoration, they have been used for cleaning dirt and removing altered protective layers, achieving highly positive results. From this perspective, the viability of applying a “green” methodology to clean a painting was investigated. The artwork used as the basis for this research is a 17th century oil painting on canvas titled “St. Anthony saving the father from the gallows”, one of the saints’ bilocation miracles. Of unknown authorship, the painting presents pathologies aligned with case studies where the use of enzymes shown promising results. Part of this investigation involved examining the painting’s history and provenance. It was originally located in a private chapel in Torre de Moncorvo and Vitor Serrão believes it may have come from the now-defunct Convent of St. Francis in the same town. On the reverse side of the painting, an inscription and drawing of charcoal were identified and thoroughly analysed. The painting entered the Douro Museum in 2023 as part of the project “Identify to Conserve”, which aims to preserve cultural heritage at risk in the Douro Demarcated Region. The painting exhibited numerous overpainted areas and two heavily altered protective layers applied at different times. The most recent layer covered remnants of an older one, which likely had not been fully removed due to the challenges involved. FTIR analyses revealed complex mixtures in these layers, suggesting the presence of natural resin in the older varnish and a combination of acrylic resin and wax in the more recent one. The green paint layers were completely overpainted with oil paint, and an incomplete cleaning attempt had left these areas heavily stained and uneven. The aim of the project was to test enzymes for removing these layers and explore their use in combination with PVA-B hydrogels. Various formulations of enzymatic solutions were tested, including enzyme kits, enzymatic soap, and buffered gelled solutions. A specific protocol was developed to evaluate the effectiveness of cleaning, aiming to understand the mechanisms of interaction between the enzymes and the different tested media, assessing their functionality, efficiency, and limitations. This approach allowed for a systematic and replicable comparison. Different formulations of PVA-B combined with solvents were tested to address issues that could not be resolved with enzymes alone, such as the removal of overpaints and restoring the readability of all areas with green paint layers.
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Keywords
Enzimas PVA-B Pinturas de cavalete Pintura séc. XVII Enzymes Easel painting 17th-century painting
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CC License
Without CC licence