Proposta de um novo consolidante para suporte de madeira em pintura de cavalete com solventes de baixa toxicidade

• Autor(a) principal: Carvalho, Carina Real
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10451/44210
• topic: Conservação e restauro; Pintura de cavalete; Madeira - Composição química; Consolidação; Solventes de baixa toxicidade; Factores de degradação; Estudos de caso; Laropal A81; Domínio/Área Científica::Humanidades::Artes

This research is based on the proposal of a new consolidant for easel painting wooden supports. The proposed consolidant is a urea-aldehyde resin, commercially known as Laropal® A81. The use of this in Conservation and Restoration is recent, around 20 years. The choice of this resin is associated with its good properties, such as low molecular weight and the possibility of dissolving it in low toxicity solvents. The use of high toxicity products is frequent in consolidation, which inherently turns into a safety risk for operators and the environment. As such, the objectives of the consolidation of wood supports were referred, presenting a bibliographical review regarding the consolidants used in the past and present and regarding the characteristics they should have. The same analysis was performed for the solvents. The properties of Laropal® A81 and its employability in Conservation and Restoration were also presented. Additionaly, the characteristics of wood and the evolution of woody supports from ancient times to the present were also addressed. Due to the scarcity of information about its use in contemporary art, a questionnaire termed “Wooden supports of easel painting in contemporary art” was conducted. The analysis of the results of this questionnaire allowed us to conclude that the use of wood in easel painting is a current practice, and the type of species that they use most is pine. Wood consolidation is usually employed when the wood is debil, result of degradation by pests, particularly caused by xylophagous insects. These arise due to temperature and relative humidity oscillation, which lead to the analysis of these phenomena. Lastly, physicochemical tests were carried out to verify if Laropal® A81 has the required properties to be used as a consolidant and to assess how it interacts with the wood substrate. These assays were also applied to Regalrez® 1126 and Paraloid® B72 resins to obtain comparative results, in which low toxicity solvents were also used. Laropal® A81 was diluted in Mostanol and Dowanol PM, Regalrez® 1126 in cyclohexane and Paraloid® B72 in butyl etanoate. These solutions were impregnated in wooden samples, followed by tests with different objectives: morphological observation of the woods; evaluation of brightness changes; perception of the permeability of the woods in punctual and total manners; comprehension of the penetration of resins in wood; analysis of hardness increase and type of abrasion. Within the resins tested, better results were obtained with Regalrez® 1126 while Paraloid® B72 showed worse effects. Laropal® A81 results varied, however better results were achieved with Mostanol solvent. Finally, a consolidation treatment was performed on a XVII century wood painting to test Laropal® A81, dissolved in Mostanol, as a consolidant. This solution proved to be effective in this treatment as it penetrated easily.