A case study of renaissance wall paintings in Granada (Spain): historical–artistic analysis, materials characterization, and state of conservation

The research carried out on the wall paintings of Hernán Pérez del Pulgar’s Palace chapel in Granada (Spain) was aimed at determining its historical–artistic, stylistic, technical, and compositional aspects. For this, a 16th century frieze and an 18th century pendentive were studied. The mineralogical, chemical, and textural characterization of the constituent materials and the study of the state of conservation of the paintings have helped to determine the pictorial technique used, identify the nature of the salts present in the paintings, and other pathologies including a dormant fungal attack. To this end, optical microscopy (OM), X-ray diffraction (XRD), Field emission scanning electron microscopy with microanalysis (FESEM-EDS), and micro-Raman spectroscopy (MRS) were used. The information obtained helps clarify important aspects of the painting technique used, laying a basis to ensure effective and suitable conservation and restoration measures on the paintings that will ensure their durability over time.AERIMPACT | Ref. CGL2012-30729EXPOAIR | Ref. P12-FQM-1889Ministerio de Ciencia e Innovación | Ref. PID2020-119838RA-I00Grupo de Investigación de Andalucía | Ref. RNM-17

The fresco wall painting techniques in the Mediterranean area from Antiquity to the present: A review

Fresco wall paintings are one of the oldest artforms in our cultural heritage, dating back to the second millennium BC. In this work, we carry out a thorough review on the evolution of the fresco wall painting technique from Antiquity to the present day. Focused on the Mediterranean area, the aim is to gather in-depth information on different technological aspects of this decorative artform such as execution procedure, materials used and pictorial palette. Considering that the recognition of the pictorial technique (a fresco, a secco, or a mezzo fresco) is often difficult since the identification of organic binders can be a challenging issue, the assignment of well-known non-alkaline-resistant pigments to the fresco technique might not always be precise. With this in mind, this review aims to highlight the contradictions found between the bibliographical sources on the fresco technique and recent scientific studies in relation to the preparation of materials, the execution on the wall and the incompatibility of certain pigments with the alkaline environment created by this pictorial technique.Agencia Estatal de Investigación | Ref. PID2020-119838RA-I00Xunta de Galicia | Ref. ED431F 2022/07Agencia Estatal de Investigación | Ref. RYC2020-028902-IUniversidade de Vigo/CISU

Effects of using tea waste as an additive in the production of solid bricks in terms of their porosity, thermal conductivity, strength and durability

In this paper, we investigated the use of tea waste as an additive in the production of traditional bricks. This could provide several environmental and economic benefits, as well as improving thermal insulation in construction. To this end, we produced brick samples with 0,5 and 10 w% of tea waste mixed with a clayey material from Teruel (Spain) that was rich in quartz and phyllosilicates and had smaller amounts of carbonates. These samples were fired at 800, 950 and 1100 ºC in an electric oven. We then analysed and discussed their chemical, mineralogical, textural and physical-mechanical behaviour and evaluated their durability in response to salt crystallization. The pore system of the bricks was examined using a combination of different analytical techniques (hydric tests, mercury intrusion porosimetry and digital image analysis). We also evaluated their thermal conductivity and observed that an increase in the firing temperature and the amount of tea waste altered the texture of the bricks, increasing their porosity. This happened above all at 1100 ºC, where it led to the appearance of a new family of pores and increased the porosity to about 39% for bricks made with 10 w% added tea waste. The increased porosity made the bricks lighter. The bricks made with tea waste showed higher levels of water absorption and poorer mechanical strength. Our results suggest that the addition of tea residues strongly decreases the thermal conductivity and heat diffusion capacity of the bricks. They could therefore be used as lightweight bricks for the thermal insulation of buildings.Junta de Andalucía Research Group RNM179Ministry of Science and Innovation under research projects PID2020-119838RA-I00 and B-RNM-188-UGR20 of the Regional Ministry of University, Research and Innovation of the Junta de Andalucía and FEDER, a way of making EuropeFunding for open access charge: Universidad de Granada / CBU

The fresco wall painting techniques in the Mediterranean area from Antiquity to the present: A review

Fresco wall paintings are one of the oldest artforms in our cultural heritage, dating back to the second millennium BC. In this work, we carry out a thorough review on the evolution of the fresco wall painting technique from Antiquity to the present day. Focused on the Mediterranean area, the aim is to gather in-depth information on different technological aspects of this decorative artform such as execution pro- cedure, materials used and pictorial palette. Considering that the recognition of the pictorial technique ( a fresco, a secco, or a mezzo fresco ) is often difficult since the identification of organic binders can be a challenging issue, the assignment of well-known non-alkaline-resistant pigments to the fresco technique might not always be precise. With this in mind, this review aims to highlight the contradictions found between the bibliographical sources on the fresco technique and recent scientific studies in relation to the preparation of materials, the execution on the wall and the incompatibility of certain pigments with the alkaline environment created by this pictorial technique.Research Projects PID2020-119838RA- I00 and ED431F 2022/07Xunta de Galicia project Limpeza sostible do patrimonio pictorico: optimizacion dos procesos de ablacion laser ( ED431F 2022/07 )Spanish Science and Innovation Ministry project RYC2020-028902-ISpanish Science and Innovation Ministry project RYC2020-028902-IState Research Agency (SRA)Ministry of Science and Innovation under the Research Project PID2020-119838RA-I00Junta de Andalucía Research Group RNM179Funding for open access charge: Universidade de Vigo/CISU

Present and future of chromatic reintegrations of wall paintings

The chromatic reintegration of wall paintings, also known as inpainting, is a common practice in the con- servation and restoration of Cultural Heritage (CH). The main objective of the treatment is to make the narrative content of paintings with lacunae (i.e. missing paint) more artistically and iconographically leg- ible. Very few scientific studies have addressed the suitability and durability of the materials used in this kind of procedure, despite the importance of this question. Even less information is available regarding wall paintings, which are more susceptible to deterioration than other artworks due to their partial or complete exposure to extreme environmental agents (relative humidity, ultraviolet radiation, etc.). To this end, we have carried out a review of this subject bearing in mind that chromatic reintegrations should also comply with the principles of recognizability, reversibility and compatibility established in the mid- 20th century. In this review, the influence and behaviour of pigments, binders (e.g. gum Arabic, mastic or urea-aldehyde resin, etc.) and protectors are discussed, together with the latest modern restoration practices based on ‘mineral painting’, in which silicates are used as binders. Overall, this field of study deserves more attention as the materials being used have not yet been thoroughly evaluated. These ma- terials should be further assessed in terms of their visual and chemical-mineralogical compatibility with the original painting, their durability and stability in the long term under adverse weather conditions, and their reversibility.European Union in the framework of the FSE+ Galicia 2021-2027 programXunta de Galicia project Limpeza sostible do patrimonio pictorico: optimiza- cion dos procesos de ablacion laser ( ED431F 2022/07 )Spanish Science and Innovation Ministry project RYC2020–028902-

Estudio mineralógico, textural y físico-mecánico de morteros de cal hidráulica curados en distintas condiciones de humedad relativa

This work focuses on the chemical-mineralogical, textural and physical-mechanical properties of hydraulic lime mortars made with siliceous and calcareous aggregate. Mortars were cured at 60% and 90% of relative humidity, so as to assess the variability of mortar petrophysical properties in the hardened state due to the moisture conditions. The final aim was to determine the most adequate moisture conditions to be maintained during application and hardening of hydraulic mortars intended for repair interventions. We found out that using a calcareous aggregate and curing mortar at 90% of relative humidity give place to better textural and mechanical properties. However, these characteristics mostly depend on the maximum size of the aggregate grains, which should be smaller than 6 mm, in order to avoid the occurrence of mechanical discontinuities in the mortar.En este trabajo se han estudiado las propiedades químico-mineralógicas, texturales y físico-mecánicas de morteros de cal hidráulica elaborados con áridos silíceo y calcítico. Estos morteros se han curado al 60% y 90% de humedad relativa, con el fin de evaluar las eventuales diferencias en las propiedades petrofísicas de los morteros una vez endurecidos y así establecer cuál de los dos ambientes es recomendable durante la aplicación y fraguado de morteros de cal hidráulica destinados a obras de restauración. Se ha encontrado que el uso de un árido de composición calcítica y el curado al 90% de humedad relativa dan lugar a morteros hidráulicos con mejores características texturales y propiedades mecánicas. De todas formas, estas características dependen principalmente del tamaño máximo del árido empleado, que debería ser inferior a 6 mm para evitar discontinuidades mecánicas en el mortero.This study was financially supported by the Spanish research group RNM179 of the Junta de Andalucía, by the research project MAT-2012-34473 and by the Institute of Conservation and Restoration of Cultural Heritage of the CICOP foundation (ICON-CICOP)

The Characterization of the Building Materials Used in the Refectory of the Manzana Jesuítica in Córdoba (Argentina) on the Basis of a Study of Its Historical Background and the Archaeological Evidence

This paper explores the historical and geological background of the refectory of the Manzana Jesuítica in the city of Córdoba (Argentina), as a basis for characterising some of the building materials used in it. The aim is to gain a better understanding of the raw materials, labour, and production methods employed by the Jesuits in the seventeenth and eighteenth centuries. To this end, six fragments containing brick, render, and paint layers were studied by X-ray diffraction and using optical and scanning electron microscopies. Our results show that the ceramics differed solely in terms of their firing temperature, while the mortars were either air lime- or gypsum-based. The paints, mainly lime-based with clays, have similar mineralogical compositions, with some differences in colour due to the presence of goethite. This study demonstrates that the Jesuits, through their strategically situated settlements in the province of Córdoba, developed an economic system for the extraction and transport of raw materials, centred around the use of local resources. This, combined with construction techniques imported from Spain and adapted to local circumstances, was a sign of the adaptability of the Jesuit Order and their lasting influence on the region. Understanding the materials and techniques used by the Jesuits provides valuable insight into the methods of construction employed in historical buildings, offering key perspectives for their conservation. Moreover, it highlights the significance of local resource management in the longevity and preservation of these architectural works.State Research Agency (SRA) and the Ministry of Science and Innovation under the Research Project PID2020-119838RA-I00Junta de Andalucía Research Group RNM17

Mineralogical, Textural and Physical Characterisation to Determine Deterioration Susceptibility of Irulegi Castle Lime Mortars (Navarre, Spain)

Archaeological lime mortars from the Tower Keep and West perimeter wall of Irulegi Castle (Navarre, Spain) were analysed to determine susceptibility to deterioration. Chemical, mineralogical, textural and physical characterisation was performed by different tests and multianalysis techniques in order to determine the intrinsic features of the original historical mortars at the castle. Samples from the Tower Keep are more prone to deteriorate compared with the West perimeter wall due to high water absorption capacity and high porosity. A high degree of pore interconnection, high desorption index and the presence of high pore volume in the 0.01 to 1 mu m size range affect the mortar durability since pores retain water longer inside the mortar. Local environment conditions with persistent annual rainfall, high humidity and temperature variations contribute to the decay process of the original mortar. Characterisation of historical mortars not only allows better understanding of susceptibility to deterioration but also helps the design of compatible and durable repair mortar for future interventions on historical heritage. Compatibility of new materials with the historical mortar will be ensured by studying mortar characteristics and properties.This study was possible thanks to the financial support of Junta de Andalucia Research Group RNM179 and Research Project MAT2016-75889-R

The Influence of the Type of Lime on the Hygric Behaviour and Bio-Receptivity of Hemp Lime Composites Used for Rendering Applications in Sustainable New Construction and Repair Works

The benefits of using sustainable building materials are linked not only to the adoption of manufacturing processes that entail reduced pollution, CO2 emissions and energy consumption, but also to the onset of improved performance in the building. In particular, hemp-lime composite shows low shrinkage and high thermal and acoustic insulating properties. However, this material also shows a great ability to absorb water, an aspect that can turn out to be negative for the long-term durability of the building. For this reason, the hygric properties of hemp-based composites need to be studied to ensure the correct use of this material in construction and repair works. The water absorption, drying and transpirability of hemp composites made with aerial (in the form of dry powder and putty) and hydraulic limes were investigated here and related to the microbial growth induced by the water movements within the material. Results show that hemp-natural hydraulic lime mixes exhibit the highest transpirability and drying rate, the lowest water absorption by immersion and capillary uptake and the least intense microbial attack and chromatic change. A microscopical study of the hemp shives also related their great ability to absorb water to the near-irreversible swelling of their structure under dry-wet conditions.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 326983 (NaturALiMe), and the Spanish project MAT-2012-34473 of the Ministerio de Ciencia y Competitividad. Author MB, owner of the CANNABRIC company, had some role in the design and preparation of mortar samples and in the preparation of this manuscript, but did not have any additional role in data collection and analysis