Attribution model for watercolours assigned to the Costa Rican painter Fausto Pacheco: a chemical and antimicrobial assessment
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| Autors: | , , , , , , , , , , , , , , |
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| Format: | artículo original |
| Data de publicació: | 2025 |
| Descripció: | The present study analysed five watercolours attributed to the Costa Rican artist Fausto Pacheco Hernández (1899–1966). Three belong to the Central Bank of Costa Rica’s collection—Paisaje con árbol, Paisaje con casa campesina and El puente—and the other two—Paisaje A and Paisaje B— to the Museum of Costa Rican Art’s collection. These artworks were selected due to their historical significance and the need to establish a reliable baseline for future studies. Visual inspection revealed distinct stylistic elements in each piece, prompting a detailed analysis of their conservation status, biodeterioration, and pigment composition. We employed multispectral imaging and advanced spectroscopic techniques—Fiber optic reflectance spectroscopy, X-ray fluorescence, micro-Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy— in order to identify and compare the pigments. The pigments identified were Phthalo blue, Prussian blue, ultramarine blue, yellow ochre, gamboge, Naples yellow, raw sienna, red ochre alizarin, red lead and chrome oxide green. Afterwards, we used this information as input data for a numerical model designed to determine the likelihood of attribution to Pacheco. The model consisted of five technical and material indicators, that were weighted according to relevance for attribution: type of pigments used (30%), composition and brushstroke style (25%), support materials (paper, canvas, etc.) (15%), recurring motifs and themes (20%) and aging and conservation analysis (10%). These indicators were established to help determine the authenticity of the paintings, facilitating a more accurate attribution process by calculating a cumulative authenticity probability (CAP) for each artwork, when compared to the watercolour Paisaje con árbol (a painting that art historians believe is original and used to belong to a private collector that bought artwork directly from the artist). As a result, Paisaje con casa campesina was the most similar with a 93% CAP, followed by both Paisaje A and Paisaje B (85% CAP) and, lastly by El puente (81% CAP). This research enhances the understanding of Pacheco’s artistic methods, providing crucial data for future studies on his work and era. Finally, the antimicrobial properties of two of the pigments identified—ultramarine blue and yellow ochre—were evaluated by determining their minimal inhibitory concentration for two bacterial isolates and six fungi retrieved from the artworks. We found out that ultramarine blue was more prone to microbial development than yellow ochre, since the latter inhibited growth at lower concentrations. Nonetheless, since watercolours are applied very diluted, the microorganisms isolated were able to colonise, reproduce and eventually deteriorate the artwork. |
| Pais: | Kérwá |
| Institution: | Universidad de Costa Rica |
| Repositorio: | Kérwá |
| Idioma: | Inglés |
| OAI Identifier: | oai:kerwa.ucr.ac.cr:10669/102003 |
| Accés en línia: | https://hdl.handle.net/10669/102003 https://doi.org/10.1038/s40494-025-01602-4 |
| Paraula clau: | pigment identification multispectral imaging biodeterioration antimicrobial properties cultural heritage conservation microbial colonization |