Search

The aim of this paper is to analyse facial similarity and apply it to identify the individuals depicted in the mural paintings of the apse of St. Leocadia Church, located in Chaves Municipality (North of Portugal), which were painted during the first quarter of the 16th century. This study also compares the portraits of this mural paintings with the oil paintings by the Proto-Renaissance Portuguese painter Nuno Gonçalves. Through this research, the feasibility of face recognition technology is explored to answer many ambiguities about Manueline stylistic identity and iconography. Additionally, it aims to associate historical events, artistic discoveries, and the expansion of portraiture as propaganda of power during the Portuguese Proto-Renaissance and Early Renaissance. On the other hand, it focuses on the prevalence of the religious and devotional over the sacred in Manueline painting. A proposal was made to identify the characters that are fundamental to the meaning of the mural paintings. An experiment was conducted on seven characters from the paintings at St. Leocadia Church, which were then compared to Nuno Gonçalves’ portraits. Facial similarity analysis was conducted on the faces portrayed in the Panels of St. Vincent, a remarkable portrait gallery from 15th-century Portugal, which has been the subject of national and international research for 130 years. Other paintings that were analysed were the oil paintings of St. Peter and St. Paul and of Infanta St. Joana, which were created by the same Quattrocento master. The purpose of the mural paintings of St. Leocadia Church could be catechetical in nature or related to the ritual practices of royal ancestor worship in royal portrait apses of the churches. It could also be associated with the Portuguese maritime expansion and the macro-imperial ideology of D. Manuel I.

Sixteenth-century mural paintings of Nossa Senhora das Neves in Vilar de Perdizes (Galicia—North Portugal Euroregion) were analysed. An iconographic study has allowed us to understand the meaning of the seven scenes that constitute the mural painting. X-ray fluorescence (XRF) and Raman spectroscopies determined the compounds used in this mural painting, both in the original and in later repaintings. The black paint was bone black. Hydroxyapatite characteristic bands and those of the associated phosphates have been identified. White lime was used as white paint. Lepidocrocite and goethite were used to make yellows, and hematite was used to make red shades. Cinnabar has been used for a later red repaint. Carbon-based compounds and rutile were used to create different tonalities by darkening or lightening colours. It is of great significance to obtain accurate and reliable mural painting information through scientific means, since preservation, restoration, and repainting without detailed information can be harmful to mural paintings.

Abstract The 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.

Human activity has required, since its origins, stones as raw material for carving, construction and rock art. The study, exploration, use and maintenance of building stones is a global phenomenon that has evolved from the first shelters, manufacture of lithic tools, to the construction of houses, infrastructures and monuments. Druids, philosophers, clergymen, quarrymen, master builders, naturalists, travelers, architects, archaeologists, physicists, chemists, curators, restorers, museologists, engineers and geologists, among other professionals, have worked with stones and they have produced the current knowledge in heritage stones. They are stones that have special significance in human culture. In this way, the connotation of heritage in stones has been acquired over the time. That is, the stones at the time of their historical use were simply stones used for a certain purpose. Therefore, the concept of heritage stone is broad, with cultural, historic, artistic, architectural, and scientific implications. A historical synthesis is presented of the main events that marked the use of stones from prehistory, through ancient history, medieval times, and to the modern period. In addition, the main authors who have written about stones are surveyed from Ancient Roman times to the middle of the twentieth century. Subtle properties of stones have been discovered and exploited by artists and artisans long before rigorous science took notice of them and explained them.

The carbonate stones that make up the four fountains of the 18th century located in the Paseo del Prado of Madrid (Spain) are studied. The documentary search in historical archives, together with the petrographic, cartographic and paleontological studies permitted to determine that the fountains have been built with dolostone of the Castrojimeno Formation, with gastropods of the Trochactaeon Lamarcki specie of the Santonian (Upper Cretaceous). The historical quarries from which the ashlars have been extracted is located in Redueña Village. The petrophysical properties of this dolostone (effective porosity, bulk density, mercury intrusion porosity, ultrasound wave propagation velocity, micro-roughness and color) have been calculated and compared with Colmenar de Oreja limestone. Each of the four fountains has a circular pylon at the base, a central column that holds a smaller pylon and is topped by a sculpture that serves as a spout. A bomb destroyed three ashlars of the basal pylon, column, small pylon and the sculpture of the SE fountain, during the Spanish Civil War, in 1936. These damaged elements were replaced by other carved limestones from Colmenar de Oreja in 1944. The four sculptures had been replaced in 1996 with resin replicas and the originals are preserved in the San Isidro. Los orígenes de Madrid museum. The study of the petrophysical properties of the sculptures located in the museum allowed us to determine the decay of different stone types. The analysis of micro-roughness was employed to define that the dissolution effect on the sculptures is different between dolostone and limestone. Redueña dolostone is more resistant to dissolution effect than Colmenar de Oreja limestome.