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Analysis of over 180 historical documentary sources from 1600 to 1900 covering the cleaning of oil paintings established that the use of alkalis was mentioned in over 50% of references to aqueous cleaning. Alkalis could be employed as a paste with wood ashes and water or in the form of lye. Historical alkali cleaning recipes based on wood ashes were reconstructed and characterised using titration and in- ductively coupled plasma-atomic emission spectroscopy (ICP-AES). Results indicate that pH depends on the wood-ash source, the age of both the ashes and the lye, as well as on the proportion of ash to water. Reconstructions of lye solutions and wood-ash pastes were applied to naturally aged model oil paints and oil paintings. Their visual impact was investigated using high resolution imaging, and chemical changes were studied with infrared spectroscopy in attenuated total reflection (ATR-FTIR) and focal-plane array Fourier transform infrared spectroscopy (FTIR-FPA) as well as scanning electron microscopy equipped with energy-dispersive X-ray analysis (SEM-EDX). These latter investigations determined the presence of potassium within the upper layers of paint samples after exposure to wood ash lye. The potassium remained in the oil network after extensive water rinsing. This research adds information to our existing knowledge about historical cleaning methodologies and contributes to a better understanding of the current condition of paintings previously cleaned with alkalis.

The relationship between artists’ material choices, the preparation and application of materials, and the consequences – the appearance and material properties of the art-work – are studied using Historically Accurate Reconstructions Techniques (HART). This model provides a systematic means to evoke past practices. Reconstructions focus on a range of topics, from the flow properties of Van Gogh’s paint to the colour of natural chalk used in artists’ preparation layers. As the operator physically prepares and uses the materials, the steps towards the moment of painting are re-enacted. The products of the re-enactment, the documentation and the reconstruction itself, provide evidence – visual, physical and chemical ‒ for comparison with historic oil paintings.

The present work looks at pigment surface treatments and is divided in two parts. Part I explores the relationships between pigment manufacturers, raw materials suppliers, and the artist’s oil paint manufacturer, and describes surface treatments and coatings. This is followed by a summary of the history and characterization of surface treatments and introduces the role of pigments in the formation of certain paint defects in relation to these surface treatments. Finally, it presents a tentative identification of the surface treatments of the white pigments selected for study. The research in Part I involved collecting information through research into the patent and technical literature in conjunction with interviewing a global manufacturer and supplier of raw materials/pigments and an artist’s oil paint manufacturer. This exploration revealed that pigment surface treatments can be very complex consisting of either an inorganic or organic component or both, applied in very small amounts (up to 10% wt of the pigment). This work revealed that surface treatments may find their origins very early on, as in the 14th century Montpellier Manuscript, and that treatments re-emerge in response to industrial uses and needs not specifically linked to artist’s oil paint manufacturers. Materials such as waxes and stearates, known additives for oil paints, but also alkyds, developed as organic binders, were found to have been used as surface treatments for pigments. Part II focuses on the detection and identification of surface treatments on the selected pigments, Lead White, Zinc White and Titanium White, and describes the multi-analytical approach used to investigate their surface treatments with electron microscope techniques (SEM-EDX, FEG-SEM and (S)TEM-EDX) and hyphenated mass spectrometry techniques (EGA-MS, Py-GC//MS and Py-THMGC/ MS, and DTMS). This study highlights the importance of gathering information on the pigment’s provenance and material characterization and reflects on the implications of terminology and commercial secrecy for surface treatment detection and identification. Regarding the detection and identification of inorganic treatments, both FEG-SEM and (S)TEM-EDX proved to be effective for this purpose. These techniques also provided evidence which shed light on the method of manufacture of the pigments. Although the analysis of the organic fraction present in the pigment samples proved to be challenging, pyrolysis methods did enable the identification of anticipated materials (as was the case of the polyols in Titanium White pigments) as well as the discovery of unexpected compounds such as anti-oxidants.

Pigment manufacture in the twentieth and twenty-first centuries has largely been intended for industrial application. Consequently, the artist’s materials market which is by contrast very small and specialized, relies on pigments produced for the industrial market. Improvements to enhance performance in an industrial context, has led to the introduction of a variety of different surface treatments applied to pigment particles. Pigment coatings can consist of one or more thin layers of either organic or inorganic material, or a combination of both. Their nature and their presence in very small amounts present a challenge for the detection and identification of these compounds. Part I of this thesis explores the literature covering pigment coating materials, application methods and the terminology used to identify the range and types of materials in use. Part II explores the analytical strategies that can be employed to detect these treatments on pigment samples. The pigments selected for this research include: Umber and Vine Black purchased from Kremer Pigmente during the Carlyle MOLART Fellowship for the creation of “historically accurate” paint reconstructions; Ultramarine Blue pigments since the use of coatings on these pigments is reported in the literature (for greater acid resistance); Cu-Phthalocyanine Blue pigments as these are currently amongst the most popular blue pigments; and the Hansa yellows, PY3 and PY74 from the manufacturer Royal Talens to determine the possible presence of a surface treatment or coating which could be responsible for paint instability. Analytical methods employed for this thesis work to characterize the organic fraction on pigments surfaces included: Evolved Gas Analysis Mass spectrometry (EGA/MS); Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC/MS); Py-GC/MS using thermally assisted hydrolysis and methylation (THM) with gas chromatography-mass spectrometry (GC/MS) in combination with ultrafast thermal desorption (UTD), meaning the samples were investigated through “slow pyrolysis” and not as flash pyrolysis. This method, developed at RCE, involves a temperature program that enables a one-shot analysis with evaporation before pyrolysis. To characterize inorganic materials, the following instruments were used: Scanning Electron Microscope Energy Dispersive X-ray (SEM-EDX); (Scanning) Transmission Electron Microscope Energy Dispersive X-ray ((S) TEM-EDX); and Field Emission Gun Scanning Electron Microscope (FEG-SEM). Surface treatments influence the physical properties of pigments during the manufacture of coatings, including oil paints. By understanding their applications and chemistry and determining methods for identifying them in situ on pigment particles, their influence on the long-term stability within modern artist’s oil paint can be assessed.

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.

This work resulted in one oral presentation and two publications: Paper accepted for presentation and publication, Colóquio em Investigações em Conservação do Património, “Arte e Ciência: Investigação sobre a técnica e materiais aplicados na pintura sobre cobre”, Daniel Vega, Isabel Pombo Cardoso and Leslie Carlyle. Faculdade de Belas Artes da Universidade de Lisboa (FBAUL), Lisbon. Paper accepted for publication, International Symposium Paintings on copper (and other metal plates). Production, degradation and conservation issues, “Investigation and testing to develop an infill formula suitable for oil paintings on copper”, Daniel Vega, Isabel Pombo Cardoso and Leslie Carlyle. Universitat Politècnica de València (UPV), Valencia, Espanha. The present work is divided in two parts. Part 1 concentrates on the study of the manufacture of copper plates used as a support for oil paintings since to date, there has not been a great deal of information available. The research involved comparing the information gathered from historical treatises on metallurgy and recent studies of paintings on copper and copper archaeometallurgy, with results from a set of thorough scientific analyses undertaken on the copper supports of fifteen European paintings (dating from the 17th and 18th centuries). This comparison revealed interesting insights into the metallurgic processes used to produce the copper ingot from native copper, and the subsequent manufacturing processes undertaken to obtain the copper plates. Copper ore purification was a complex and expensive process. Purification included several steps, all of which were rigorously executed as attested by the high level of purity of the copper produced. Scientific analyses undertaken on the copper supports of the fifteen European paintings revealed that the manufacture of the plates from the ingots involved cycles of cold working alternating with annealing. Hammering took place which would have been aimed to form a plate with adequate hardness, while the intermediate stage of annealing returned malleability so that further intense cold work, necessary to achieve a plate without breaking, could be carried out. Part 2 focus on the characterization of two wax-resins formulations used as infill materials for oil paintings: a formula used by Carlyle in the early 1980s (C-PWR) and Gamblin pigmented wax-resin (G-PWR). and, based on the negative impact on copper of the acidic beeswax in both formulations, an exploration to find a new formulation with a neutral acid value was carried out. Preliminary trials and testing focussed on the development of a new wax-resin formulation suitable for infills on oil paintings with a copper substrate. New options for infill materials on copper supports are particularly important as the range of infill materials currently available are not suitable, for a variety of reasons, for use on this type of support. Although ageing tests are still needed, the characterization of the individual materials, and of the new formulation, KTW5-R1, made of Techniwax 9426 microcrystalline wax with Regalrez 1094, showed that this wax resin mixture with an acid number of 0, is likely to be inert in relation to the copper and chemically stable since it is composed of saturated hydrocarbons only.

Paper submitted to e-conservation Journal: Maria Leonor Oliveira, Leslie Carlyle, Sara Fragoso, Isabel Pombo Cardoso and João Coroado, “Investigations into paint delamination and consolidation of an oil painting on copper support”. This thesis is divided into two parts. Part 1 focuses on the technical study of an undated oil painting on copper. The painting, which depicts the Biblical scene ‘The Visitation’, arrived at the laboratory in poor condition, with severe active flaking which has resulted in extensive paint losses. Part 2 investigates the range of consolidants available to treat flaking paint, and the experiments carried out to determine the suitability of a selection of these. The literature on oil paintings on copper and on consolidants used in their treatment is scarce. Based on the few articles that exist, an empirical pilot study was made of the following synthetic polymers: Paraloid B-67, Paraloid B-44, Regalrez 1094, Paraloid B-72, Mowilith 20, Beva 371b, and Laropal A 81. From these, the last four were selected for a more detailed investigation focused on their interaction with copper, specifically concerning the diffusion of copper ions into the polymeric matrices. This is a topic of interest due to descriptions in the literature of metal particles acting as catalysts in polymer degradation processes. Rutherford Backscattering Spectroscopy (RBS) was chosen to investigate this subject on a series of copper coupons coated with the four polymers. Due to beam damage of the coatings during analysis, the results were inconclusive. SEM/EDS was used to complement the information from RBS, but did not detect the presence of copper in samples from the same films, either indicating that these polymers and copper do not interact; or that the time for the accelerated ageing of the samples was too short. Nonetheless, the material study of the painting in Part 1 successfully established a date range for the painting, and new insights into substances which appear to result from interactions between the copper support and the pictorial layers were found.

The present work is divided in two parts: Part 1 is focused on the analysis and treatment of a 19th century portrait of Domingos Affonso, which belongs to the Ecomuseu Municipal do Seixal; and Part 2, which is entitled “The Microclimate Frame Project” is focused on the study of Artsorb® and on the planning of a microclimate frame for the painting. In Part 1, a study of the painting’s materials was performed using complementary analytical techniques and the painting’s condition was carefully evaluated. The painting exhibited signs of mould growth, and a more detailed investigation was made of this topic to understand if the fungal community was active and if it represented a real danger to the painting. A treatment was proposed, appropriate to the painting’s condition. A description of the treatment carried out, comprising the treatment options, is also present in this section. Within the study of the microclimate frame, in Part 2, the study of the potential corrosiveness of Artsorb® was a central subject. Artsorb® sheets are one of the most widely used materials for buffering relative humidity fluctuations in microclimate frames and its reported excellent performance is enhanced by its availability in lightweight sheets that can be easily placed inside microclimate frames. However, concerns have arisen regarding the presence of the corrosive salt lithium chloride in the composition of this buffer. Consequently, the present work also aimed to understand the potential risks of using Artsorb® and the possibility of avoiding exposure of lithium chloride to the artworks through the use of Tyvek®. Results from the preliminary tests seem to indicate that Artsorb® releases lithium chloride into air. This study also showed that a Tyvek® cover over Artsorb® reduces but does not eliminate evidence of chlorine contamination, and it significantly reduces the effectiveness of the buffering material. Considering that Artsorb® appears to be unsuitable due to the release of the corrosive salt, that Tyvek® was not efficient as a barrier for lithium chloride or as a permeable material to enable the proper functioning of Artsorb®, the buffering material proposed for the use in the microclimate frames is silica gel without indicator. Based on the choice of buffering material, as a result of this study, a microclimate frame is proposed.

This thesis project concentrated on both the study and treatment of an early 20th century male portrait in oil from Colecção Caixa Geral de Depósitos, Lisbon, Portugal. The portrait of Januário Correia de Almeida, exhibits a tear (approximately 4.0 cm by 2.3 cm) associated with paint loss on the right upper side, where it is possible to observe an unusually thick size layer (approximately 50 microns) and an open weave mesh canvas. Size layers made from animal glue remain subject to severe dimensional changes due to changes in relative humidity (RH), thereby affecting the stability of the painting. In this case, the response to moisture of the size layer is minimal and the painting is largely uncracked with very little active flaking. This suggests that the size layer has undergone pre-treatment to render it unresponsive to moisture or water. Reconstructions based on late nineteenth century recipes using historically appropriate materials are used to explore various options for modifying the characteristics of gelatine, some of which may relate to the Portrait’s size layer. The thesis is separated into two parts: Part 1: Describes the history, condition, materials and techniques of the painting. It also details the treatment of Januário Correia de Almeida as well as the choices made and problems encountered during the treatment. Part 2: Discusses the history of commercial gelatine production, the choice of the appropriate animal source to extract the collagen to produce reconstructions of the portrait’s size layer as well as the characterization of selected reconstructions. The execution of a shallow textured infill led to one publication and one presentation: Abstract accepted for presentation and publication, International Meeting on Retouching of Cultural Heritage (RECH3), Francisco Brites, Leslie Carlyle and Raquel Marques, ‘’Hand building a Low Profile Textured Fill for a Large Loss’’.

This thesis focused on the study and treatment of a 19th century female portrait in oil from ECOMUSEU Municipal do Seixal, Portugal. The portrait, which depicts Isabel Maria Lourenço Affonso was in poor condition and a large strip of paint and canvas was missing (approximately 9cm by 66cm, almost 11% of the total surface area). The portrait is a companion piece to a male portrait (the relationship was established as part of this study), therefore a technical study of both paintings was considered essential to support the choices made during the treatment. The project involved three main areas: - The study of the history, condition, materials and techniques of both paintings. This allowed their comparison and understanding of their relationship; - The treatment of Isabel Maria Lourenço Affonso. The choices made and problems encountered are described. - The production of a replacement for the missing strip of paint and canvas. The practical solution developed to overcome such an unusual challenge is described along with the creative and flexible thinking required. Because not all traditional infill materials cope well on a mechanical level with thin layers over a very large surface (many are too brittle), strict criteria had to be employed to choose the appropriate material. The primary goal was to find a fill which would remain flexible and be capable of accepting surface texture, such that there would be a good visual match with the painting. Analysis and testing was carried out to evaluate the physical properties of the fill material chosen, BEVA® Gesso-P. The successful creation of the replacement strip has resulted in two publications and one presentation: Publication pending in The Picture Restorer, Leslie Carlyle, Raquel Marques, Isabel Pombo Cardoso and Sara Babo, “Creating a Textured Replacement Strip for the Missing Lower Portion of an Oil Portrait: Problem Solving and Practical Solutions”. Abstract accepted for presentation and publication, International Meeting on Retouching of Cultural Heritage (2RECH), Raquel Marques, Leslie Carlyle and Isabel Pombo Cardoso, “Textured Replacement Strip for a Missing Portion of a Portrait: Problem Solving and Practical Solutions”.

Dissertação para obtenção do Grau de Mestre em Mestrado em Conservação e Restauro, especialização em Ciências da Conservação Brazilwood is a soluble redwood that was used as source of organic dye and for lake pigments. It was widely applied in medieval times to colour textiles and in the form of pigment for manuscript illumination and, although it is relatively unstable, it is still found in the 19th oil palette. However, this colorant has received little attention. In this sense, the present work aims to contribute knowledge on the characterisation of brazilwood and its lake pigments. The flavonoid brazilein is the red chromophore that can be extracted from the brazilwood tree. To study with more detail its behaviour, the molecule was isolated from brazilwood scrapes. As confirmed by NMR and HPLC-DAD, a high purity compound was obtained (for which a pKa1 of 7 was determined) and a pure brazilein-Al3+ complex was produced. Characterisation with UV-Vis spectroscopy and μ-spectrofluorimetry revealed that in its acidic form, the chromophore presents absorption, excitation and emission maxima at 446, 475 and 536 nm, respectively, and at 540, 548 and 560 nm when deprotonated. When complexed with Al3+ these values are changed to 510, 520 and 585 nm. Brazilwood lake reconstructions with as much historical accuracy as possible were also prepared based on recipes from the 15th century documentary text Livro de como se fazem as cores and the Winsor & Newton 19th century archive. This led to a greater understanding of the manufacture of the lakes and its evolution through time. Furthermore, in order to investigate the best strategy to characterise such pigments and paints, and to provide reference samples, the lakes produced and applied as temperas were then analysed by colorimetry, FTIR, SEM-EDS, FORS and UV-Vis μ-spectrofluorimetry. Despite some differences exist between the two sources, mainly with respect to the dye extraction method, both are guided by the same principles and are constructed in order that the same final pH, adequate for pigment precipitation, is obtained. In particular, the 15th century Livro de como se fazem as cores, so distant in time, allowed for the successful preparation of brazilwood lake pigments, which can be obtained in a variety of different hues from light pink to dark red and purple. Concerning the analysis carried out, FTIR was essential to characterise extenders, while FORS spectra (λabs 560 nm) and μ-spectrofluorimetry (λex 553 nm for excitation and λem 585-90 nm for emission) data were very consistent and fundamental to identify the brazilwood chromophore. These three techniques were essential and complementary in the characterisation of the paints produced. Medieval reconstructions were compared with pink and red colours of illuminations found in three French books of hours (Palácio Nacional de Mafra, Portugal) from the 15th century. Good correlation between FTIR, FORS and μ-spectrofluorimetry spectra of the reconstructions and historic samples suggest that the illuminations colours were prepared with brazilwood lakes.

Dissertação para obtenção do Grau de Mestre em Conservação e Restauro This project involved the conservation of a 19th century portrait in oils from the Ecomuseu do Seixal (Portugal). The painting of “João Luiz Lourenço” was in very poor condition. Because of the range and severity of the problems presented, it offered an opportunity to explore important aspects of painting conservation in-depth. The approach to its treatment required an empirical investigation of a number of materials and techniques used in the field of conservation/restoration. Of additional interest, the painting exhibits widespread evidence of metal soap (lead carboxylate) aggregates protruding through the paint from the ground layer. The painting’s materials and the metal soaps aggregates were studied and characterised with different analytical techniques: μ-EDXRF (Energy Dispersive X-ray Fluorescence), μ-Raman Spectroscopy, μ-FTIR (Fourier Transform Infrared Spectroscopy) and SEM-EDX (Electron Scanning Microscopy with Energy Dispersive X-ray Spectroscopy). Part 1: describes the study of the materials and the technique of the painting, and of the metal-soap aggregation within the painting’s ground layer. Observation with the Optical Microscope and with SEM-EDX of paint/ground cross-sections reveals the presence of two visually distinct lead carboxylate aggregates: one, completely white, and the other with a white centre surrounded by distinct red particles identified as red lead (minium: Pb3O4) by μ-Raman. The presence of these two types raises questions about whether there are different starting materials for the aggregates or whether they could be in different states of evolution. Part 2: describes the design and implementation of the conservation/restoration treatment. The treatment of the painting raised challenges and at various stages involved the exploration of non-traditional methods. At every stage during the treatment the consequences of an intervention was carefully considered in relation to the subsequent steps. All decisions were taken according to the painting’s intrinsic conservation problems and materials and with regard to the future environment of the painting.

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Conservação e Restauro, especialização em pintura sobre tela This thesis concerns the study of the materials and techniques of the painting on canvas “Interior de um Convento” belonging to the Portuguese monument Pena National Palace (PNP) and the description of the conservation treatment carried out. The study required the use of several examination and analysis tools such as OM (Optical Microscopy), UV (ultraviolet) and IR (infrared) photography, μ-EDXRF (Energy Dispersive X-ray Fluorescence), μ-Raman (Raman spectroscopy) μ-FTIR (Fourier Transform Infrared Spectroscopy) and SEM-EDX (Electron Scanning Microscopy with Energy Dispersive X-ray Spectroscopy). The conservation treatment focused on minimal intervention with the purpose of maintaining the integrity of a nineteen century painting that has never been restored until the present date. Simultaneously, a project to investigate the best back and front protection system for the PNP’s paintings collection was initiated. Relative Humidity (RH) and temperature fluctuations were measured in the Palace and inside the half-closed and fully closed systems used to protect twelve model paintings constructed for the purpose. The objective was to choose the best protection system for dampening RH and temperature fluctuations while preventing the risk of mould occurrence. The preliminary results (4 months of readings) showed that the risk of mould growth requires further study for in a more prolonged period which encompasses seasonal changes.

Dissertation presented at the Faculty of Sciences and Technology of the New University of Lisbon in fulfillment of the requirements for the Master degree in Conservation Science A detailed knowledge of the materials used by artists is essential to unveil their techniques and to place their works in context as well as to establish the most adequate conservation and authentication procedures. Such knowledge arises from reliable documentary sources of technical information contemporary to artists and the preparation of historically accurate reconstructions. Deciphering the words of the past to unravel art technology is far from straightforward, representing one of the most challenging issues within the art conservation field. Chrome yellow pigment belongs to the 19th century artists’ palette. It was enthusiastically used by many artists even when its use was deemed inadvisable. The Portuguese modern painter, Amadeo de Souza-Cardoso, was one of these artists known to have used it. The aim of this work was the manufacture of chrome yellow pigments with as much historical accuracy as possible. This was the first time the Winsor & Newton 19th Century Artists’ Materials Database was systematically explored to support pigment manufacture. The recipes taken from this database were broken down into their relevant steps. This study proposes a correct correspondence between original materials and their current equivalent. A total of 34 pigments and 3 minerals were characterised by EDXRF, Raman, FTIR, XRD and SEM-EDS. Regardless of the recipe or process variations, lead chromate was identified in the majority of the pigments. Depending on the pH, other compounds were also detected. Basic lead chromate was obtained under alkaline conditions, giving rise to an orange hue. Mixed-crystals of lead chromate and lead sulphate were formed under acidic conditions, presenting a lemon hue. All the extenders used, namely calcite, barytes and gypsum, were detected. Notably, cerussite and calcite were also identified even though they were not added as such during the pigment manufacture. Moreover, a comparison with case studies samples was performed. Pure lead chromate and mixed-crystals of lead chromate and lead sulphate were identified in the presence of calcite, barytes and cerussite. Proposals concerning the formulation of these pigments are suggested. A multi-analytical approach proved to be fundamental for the characterisation of all the pigments.

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro