The Aesthetic Treatment of a Painting on an 18th Century Coach

The main objective of this thesis was the study and treatment of an oil painting on the upper back panel of an 18th century coach in the collection of Museu Nacional de Coches (MNC), Portugal. The painting is a symbolic representation of the Portuguese Monarchy and of Royal Power depicted by a female figure sitting on a throne with her right arm resting on the Portuguese Royal Shield of Arms. All the figures, including the Monarch, wear classical costume. The aesthetic appearance of the painting was significantly compromised. Large areas of the varnish were matt rather than shiny, and previous re-integrations were not saturated in colour, standing out from the original. In the centre of the panel, the join between two horizontal planks had separated and had been filled and reintegrated. The fill had developed a large obvious crack, with associated losses to the reintegrated paint on the fill. Infilling which had been applied over nail heads in other areas on the panel were disturbing since they were also cracked and had an uneven texture compared to that of the original painting. The coach has a total of 11 painted panels, which were also examined as part of this work. This thesis project focused on four main areas: - The study of the history, materials and techniques of the paintings on the coach. This involved research on 5 treatises on coach construction and decoration dating from 1858s to 1903, published in, France, England and United States,to evaluate the materials and methods recommended; - The evaluation and identification of the materials and techniques for the paintings using stratigraphic analysis and analytical techniques. This was carried out with the support of Laboratório HERCULES. Due to time constraints, analysis was focused on the Upper Back Panel. For comparison of the materials present, μ-EDXRF was also carried out on 4 of the side panels as well as the Upper Back Panel; - The full evaluation of the condition of the Upper Back Panel in order to develop an aesthetic treatment strategy; - The execution of the treatment of the Upper Back Panel with the supervision of the Instituto José de Figueiredo. The study of coach painting treatises revealed that it was common for paintings on these vehicles to become damaged. As a result it was expected that paintings would be routinely removed and replaced. Therefore although the coach may have been constructed in the 18th century, the current paintings could be from later centuries. After analysis of the upper back panel using μ-EDXRF, μ-FTIR, μ-Raman and SEM-EDS it was found that no elements or pigments specific to an time after the 18th century were present, except in areas of intervention. The materials original to the paintings which were identified during this thesis include: lead white, vermilion, ochres (hematite and goethite), green earth and Naples yellow; as well as the fillers, calcium sulphate and calcium carbonate. The aesthetic treatment undertaken was successful in restoring gloss to matt areas of varnish along with re-saturating previous re-integrations and overpaint. Previous colour re-integrations were also retouched and the surrounding varnish colour re-integrated such that the visual impact of the discordant previous treatments was reduced and no longer became the focus of the painting.