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The physicochemical investigation of ceramics crafted and managed by ancient humans allows a better understanding of their social, technological, economical, routine and artistic activities. The Brazilian State of Rio Grande do Sul presents the biggest number of registered archaeological sites in the country, and many of them are earthen mounds, locally known as cerritos de indios. This kind of archaeological site is of utmost importance to understand the social development of the biome Pampa – including areas from Brazil, Argentina and Uruguay – and almost nothing is known about the physicochemical composition of the artifacts from the Brazilian portion. In this work we investigated the mineral phases present in archaeological ceramics from the cerrito Pavao I (PSG-20) by means of white light microscopy (petrography), Raman micro-spectroscopy, XRD and XRF spectroscopies, and FTIR-ATR. Different minerals were identified and allowed to propose a firing temperature of ca. 500–650 °C. It was also suggested that the makers used both oxidizing and reducing atmospheres, that more than one clay source was used to prepare the ceramics, and that trace elements are present in different shards. Regarding the multi-analytical technique approach, the results highlight the importance of complementary investigations and underline the role of Raman micro-spectroscopy for these objects.

The understanding of chemical and physical behavior of materials, especially metals and their alloys, is of utmost importance for industrial and technological applications, development of new materials and preservation of cultural heritage. The use of complementary analytical techniques has allowed a better understanding of corrosion mechanisms, and results obtained by Raman micro-spectroscopy, for example, have been complemented by FTIR and XRD. When focusing on the development of new materials and proposition of preservation strategies, the understanding of corrosion processes and of their very initial steps (nanometric scale) is fundamental. SERS reaches such lateral resolution if TERS is used, however, it cannot be universally applied and needs to be complemented by other techniques. In this work it is presented the potentials of a recent installed technique at the Brazilian Synchrotron Light Laboratory (LNLS), which can be used for nano-speciation of corrosion products, complementing investigation carried out by, for example, Raman micro-spectroscopy and TERS. It is Synchrotron Infrared Nano-Spectroscopy (SINS), which allows the investigation of both chemical nature and physical distribution of corrosion products. The infrastructure presented at LNLS is one of the few available in the world. As a model system, thin films of Pb exposed to formic acid were used.

Vibrational spectroscopy and GC–MS were used to investigate the effect of MnO 2 and α-Fe 2 O 3 on the degradation of methyl linoleate and vegetal and animal fatty. The metal oxides are among the most employed pigments in rock art paintings, whereas the organic compounds were used to mimic organic binders potentially used in such paintings. Both oxides were very effective in the catalytic oxidation of the organic substrates and light had no significant effect, qualitatively or quantitatively, on the final products. In the case of methyl linoleate without metal oxide, the effect of light (visible) was investigated and it was demonstrated that the samples kept in the dark produced relatively less oxidation products, although the main products were the same (hexanal, methyl 9-oxononanoate and methyl octanoate). In the presence of MnO 2 and α-Fe 2 O 3 methyl 9-oxononanoate was the main product, followed by hexanal. The spectral patterns of the oxidation products were different for manganese and iron oxide and GC–MS demonstrated that more compounds are formed in the former than with α-Fe 2 O 3 . Vegetal and animal fatty presented the same behavior that methyl linoleate did. The results here reported indicated that the two pigments considered actively contribute to fat degradation and the presence of inorganic pigments is the main factor to take into account when organic binders degradation in rock art paintings are investigated.

Esta Tese de doutorado teve por objetivo aumentar a compreensão dos aspectos sinérgicos na corrosão de bens culturais feitos com chumbo (Pb) e avaliar a agressividade ambiental sobre bens culturais em igrejas e museus brasileiros para a proposição de estratégias de conservação. Neste contexto, foram investigados, em microambientes simulados, os efeitos sinérgicos entre formaldeído e ácido acético, ácido fórmico ou dióxido de carbono na corrosão de Pb; foi feita a síntese e caracterização de diferentes formiatos gerados nos processos de corrosão de Pb por formaldeído ou ácido fórmico; foi avaliada a agressividade ambiental sobre bens culturais da Igreja de São Francisco (São Paulo, ambiente urbano industrial), da Igreja dos Freis Carmelitas (Santos, ambiente urbano industrial costeiro), do Museu de Arte Contemporânea da USP (MAC, São Paulo, reserva técnica da nova sede) e do Museu de Arqueologia e Etnologia da USP (MAE, São Paulo, reserva técnica), através de cupons metálicos (chumbo e cobre) expostos nos ambientes interno e externo dessas instituições e através do uso de monitores miniaturizados; foi feita a otimização destes monitores e, finalmente, foi considerado o desenvolvimento de um nariz eletrônico (EN) baseado em microbalanças de quartzo (QCMs) para o uso em conservação preventiva. Nestas investigações microscopia Raman foi a principal técnica empregada, sendo que as demais foram FTIR-ATR, µ-FTIR-ATR, µ-FTIR, nano-FTIR (SINS), s-SNOM, AFM, SEM, SEM-EDX, XRD e SR-XRD. Os resultados apontaram para a necessidade de individualização dos objetos artísticos tanto para a proposição de estratégias de conservação quanto para o entendimento de sua reatividade, mostraram a agressividade ambiental de todas as instituições investigadas, indicaram a potencialidade de ENs em conservação preventiva e demonstraram a utilidade de técnicas de alta resolução lateral, como nano-FTIR, em investigações de corrosão metálica. Mais especificamente, as investigações de sinergia entre poluentes aumentaram o entendimento da reatividade de Pb e permitiram a proposição de esquemas mais completos de sua reatividade, levando a discussões acerca da conservação desses bens. A agressividade química ambiental das igrejas e museus a bens culturais foi inferida pela caracterização de cupons metálicos expostos em seus interiores e exteriores, enquanto que a agressividade relacionada a fatores físicos, como temperatura e umidade relativa, foi inferida através do uso de monitores miniaturizados expostos somente nas igrejas. Com esse monitoramento, estratégias de conservação foram propostas. Para a devida caracterização dos cupons metálicos, expostos nas igrejas e museus ou nos microambientes simulados, a síntese e a caracterização de diferentes formiatos de Pb foi essencial. Por fim, visando melhorar o desempenho dos monitores miniaturizados e ampliar sua aplicabilidade (com seu futuro uso como EN), um novo dispositivo foi construído e um estágio na Universidade de Aveiro, em Portugal, foi realizado para o desenvolvimento de um EN baseado em QCMs. The objective of this doctoral thesis was to increase the understanding of synergistic aspects in the corrosion of cultural objects made with lead (Pb) and to assess the environmental aggressiveness on cultural objects of Brazilian churches and museums in order to propose conservation strategies. In this context, in simulated micro-environments, the synergistic effects between formaldehyde and acetic acid, formic acid or carbon dioxide in Pb corrosion were investigated; the syntheses and characterization of different formates generated by formaldehyde or formic acid in Pb corrosion processes was conducted; the environmental aggressiveness on cultural objects of the church of São Francisco (São Paulo, urban industrial environment), of the church of the Carmelite Friars (Santos, urban industrial littoral environment), of the Museum of Contemporary Art of the USP (MAC, São Paulo, new site) and of the Museum of Archaeology and Ethnology of the USP (MAE, São Paulo) was assessed exposing metal coupons (lead and copper) in their internal and external environments and using miniaturized monitors; these monitors were optimized and finally, the development of an \'electronic nose\' (EN) based on quartz crystal microbalances (QCMs) was considered for preventive conservation. In these investigations the principal technique employed was Raman microscopy, and FTIR-ATR, µ-FTIR-ATR, µ-FTIR, nano-FTIR (SINS), s-SNOM, AFM, SEM, SEM-EDX, XRD and SR-XRD were also used. The results pointed out to the necessity of individualization of the artistic objects when investigating their reactivity or when proposing conservation strategies, showed the environmental aggressiveness of all the investigated institutions, indicated the potential of ENs in preventive conservation and demonstrated the utility of techniques of high lateral resolution such as nano-FTIR for the investigation of metal corrosion. More specifically, the investigations of synergistic effects between gaseous pollutants increased the understanding of Pb reactivity and allowed to propose more completed schemes of its reactivity, which allowed discussions on the conservation of these objects. The aggressiveness related to the environmental chemical composition of the churches and museums was inferred through the characterization of metal coupons exposed in their indoor and outdoor environments, whilst the aggressiveness related to physical factors such as temperature and relative humidity was inferred through the use of miniaturized monitors exposed only in the churches. With this monitoring, conservation strategies were proposed. For the well characterization of the metal coupons, exposed in the churches and museums or in simulated microenvironments, the syntheses and characterization of different Pb formates were essential. Finally, aiming at still improving the performance of the miniaturized monitors and increasing their applicability (in their future use as EN), a new device was constructed, and an internship was considered in the University of Aveiro, Portugal, for the development of an EN based on QCMs.

A few years ago, during a storage room clean out at the University of Sao Paulo (Biblioteca do Conjunto das Quimicas), several items were discarded, including apparently modern worthless large-scale reproductions of paintings by famous painters. A member of staff retrieved these reproductions from the litter bin, one of which was carefully inspected and non-destructively analyzed by spectroscopic techniques (Raman and XRF). The results showed that instead of being a modern reproduction of the gouache "Clinique de Sannois" (Maurice Utrillo, 1923), it was hand-painted probably between the late 1940s and early 1950s using the Jacomet process. This technique was developed by the French printer Daniel Jacomet in the 1920s, who made authorized reproductions of works of art by some of the most celebrated painters of the time.

In the present work, Raman Microscopy was employed in the characterization of the pigments used in a drawing assigned to Tarsila do Amaral, one of the most important Brazilian artists. The work (colored pencil on paper), supposedly produced in the 1920 decade, is of a very simple composition, where blue, green and brown were the colors used. Prussian Blue was found as the blue pigment, whereas green was a mixture of copper phthalocyanine and a yellow dye, probably a diarylide; the brown pigment was a carbonaceous compound. Prussian Blue was replaced by phthalocyanine as pigment since the end of the 1930's and the possibility that it could have been used as pigment in the 1920's can be ruled out.

Nesta curta introdução apresenta-se uma breve contextualização da Arqueometria e um breve relato da realização, atividades e trabalhos apresentados no V Congresso Latino-Americano de Arqueometria (V CLA). Mostra-se quantitativamente as origens dos diferentes trabalhos apresentados (no contexto de seus países), suas áreas de concentração dentro da Arqueometria e as técnicas analíticas empregadas. Comenta-se brevemente, ao final, os trabalhos publicados neste dossiê temático, dentro da presente edição da revista Cadernos do LEPAARQ.

The present work is focused on the role of formaldehyde in indoors Pb corrosion, that is still a controversial issue. Pb coupons were exposed to the atmosphere produced by formaldehyde aqueous solutions (1% and 4% in volume) and corrosion was followed by Raman Microscopy. The compounds formed in both experiments were the same, but were not in agreement with previously reported results in the literature, that identified plumbonacrite, hidrocerussite and Pb oxide. The experiments here reported have clearly shown that formates are produced on Pb surfaces exposed to formaldehyde and that oxidants, such as H2O2, are not necessary. Formaldehyde oxidation also occurs with powdered PbO in a controlled environment. The Raman spectra of the Pb formates are much more complex than the Pb(HCO2)2 spectrum and change when exposed to room conditions, by a slow reaction with CO2, forming Pb carbonates (hidrocerussite and plumbonacrite mostly) and Pb(HCO2)2. Such spectral change may be responsible for the differences in terms of chemical composition of the corrosion layer when the data here reported is compared with the literature. Other factors that must be considered are the storage conditions (particularly relative humidity and CO2 concentration) and time; the effect of metal composition cannot be discarded as it is well known that the presence of other metals can change significantly the Pb resistance to oxidation.

O presente trabalho teve por objetivo compreender o papel de íons metálicos na degradação de gordura vegetal e animal, assim como na geração de formiatos. Nesse contexto foram investigados: 1) o papel de formaldeído na corrosão de peças de chumbo e a possibilidade de CO2 ser reduzido a ácido fórmico (ou formiato) por íons metálicos presentes em vidro; 2) o papel de íons metálicos na degradação de gordura animal e vegetal, desde que um grande número de pigmentos são minerais e tais gorduras foram frequentemente utilizadas em pinturas. Espectroscopia Raman foi a principal técnica empregada nas investigações, nas quais também foram usadas FTIR, difratometria de raios X, microscopia eletrônica de varredura, refletância no visível e análise elementar (C e H). Os resultados obtidos indicaram que formaldeído é agressivo a Pb mesmo na ausência de oxidantes como H2O2 e formiatos foram detectados como produto de corrosão para concentrações de aldeído tão baixa quanto 100 ppb (100% de umidade relativa). As concentrações investigadas de H2CO foram 100 ppb, 500 ppb, 1,2 ppm, 44 ppm e 1,6x102 ppm e para todas essas foram observadas bandas de carbonato e de formiato, embora em muitos casos os espectros não foram simplesmente a soma das contribuições das bandas de Pb(HCO2)2 e PbCO3, revelando um complexo equilíbrio envolvendo as concentrações de H2CO, CO2 e H2O. O efeito de umidade relativa (54%, 75% e 100%) foi estudado e formiato foi detectado mesmo em umidade relativa de 54%. Os mesmos produtos de corrosão foram observados quando cupons de Pb e PbO foram expostos a formaldeído, evidenciando o papel da camada de óxido na oxidação de formaldeído a formiato. Quando o efeito de Fe(III) foi considerado, câmaras climáticas foram usadas e o efeito de íons metálicos foi investigado na presença e ausência de luz. Linoleato de metila, gordura vegetal e animal foram mantidos por 8 dias sob condições controladas e as mudanças na composição foram acompanhadas por espectroscopia Raman e FTIR. As amostras mostraram ser sensíveis tanto a luz quanto a Fe(III), no entanto, problemas com as duplicatas não permitiram que conclusões pudessem ser obtidas dos experimentos. Como uma etapa preliminar no intuito de estender os estudos de degradação de gorduras à química forense, um desenho de suposta autoria de Tarsila do Amaral que teria sido feito na década de 1920, foi analisado por microscopia Raman. Ftalocianina azul (ftalocianina de cobre) foi encontrada como componente dos traços verdes e desde que esse pigmento começou a ser comercializado em 1937, pelo menos a data assinalada ao desenho não é correta. The present work aimed at the understanding of the role played by metal ions on the degradation of vegetal and animal fats and on formates formation. The following issues were addressed: 1) the effect of formaldehyde on the corrosion of Pb objects and the possibility of CO2 reduction to formic acid (or formate) by the metal ions present in glass framework; 2) the effect of metal ions on the degradation of vegetal and animal fats, since a large number of pigments are minerals and such fats were often used as paint binders in the past. Raman microscopy was the main technique employed in the investigations which also used FTIR, XRD, SEM, UV-VIS absorption and elemental analysis (C and H). The obtained results indicated that formaldehyde is harmful towards Pb even in the absence of oxidants such as H2O2 and formates were detected among the corrosion products for aldehyde concentrations as low as 100 ppb (100% relative humidity). The investigated H2CO concentrations were 100 ppb, 500 ppb, 1,2 ppm, 44 ppm and 1,6x102 ppm for all of them bands assigned to carbonates and formate were observed, although in most cases the spectra were not simply the sum of Pb(HCO2)2 and PbCO3 contributions revealing a quite complex equilibria involving H2CO, CO2 and H2O concentrations. The effect of relative humidity (54%, 75% and 100%) was studied and formate was detected even at 54% RH. The same corrosion products were observed when both Pb cupons and PbO were exposed to formaldehyde thus making clear the role played by the oxide layer in the formaldehyde to formate oxidation. When the effect of Fe(III) was considered, a home made environmental chamber was used and the effect of the metal ions was investigated in the presence and absence of light. Methyl linoleato, vegetal and animal fats were kept by 8 days under controlled conditions and the changes on composition were followed by Raman and FTIR spectroscopies. The samples proved to be sensitive to both light and Fe(III), however, problems with the replicates so far don\'t allow any conclusion to be driven from the experiments. As a preliminary step in the attempt to extend the fat degradation study to forensic, a draw supposedly authored by Tarsila do Amaral in the 1920 decade was investigated by Raman microscopy. Phthalocyanine Blue (copper phthalocyanine) was found as a component of the green traces and since phthalocynines trade started in 1937, at least the date assigned to the draw is not correct

A whitish crystalline-like coating was observed on the surface of the painting "Incendio", 1990, produced by Emmanuel Nassar and awarded at the 6th Biennial of Cuenca. This work belongs to the Contemporary Art Museum of the University of Sao Paulo (MAC-USP) and such coating modified the artwork characteristics, causing an unpleasant effect and compromising its exhibition. The choice of the proper conservation and restoration strategies involves the understanding of the degradation process, demanding the identification of the chemical compounds formed on the painting surface, as well as of the other components in the painting. The results here obtained from Raman and optical microscopies, FTIR-ATR, SEM-EDS and GC-MS, revealed that the efflorescence chemical composition is almost only palmitic acid, with minor contents of stearic acid and their methyl esters, and that the paints are composed by chrome yellow, amorphous carbon and toluidine red pigment; an aluminum silicate filler in the black paint applied on the aluminum ground was also detected. Hierarchical Cluster Analyses (HCA) of the Raman spectra also revealed that the concentration of the efflorescence minor components depends on the paint composition. It was suggested, therefore, that the degradation process resulted from segregation and migration of mainly palmitic acid from the dried paints. Restoration methodologies used in similar cases, as well as factors that contribute to this process, were discussed.

Bens culturais materiais, sejam eles móveis ou imóveis, são constituídos por matéria, que é passível de sofrer processos de degradação. Esses processos levam à perda de informações materiais e imateriais e geralmente são decorrentes de reações químicas ou processos físicos, associados ou não à presença de micro-organismos. Eles dependem, além da composição química e da estrutura física do bem, das características do ambiente e/ou microambiente que os cercam. Considerando isso, portanto, e na temática do seminário “Ciência da conservação e o uso de ferramentas de caracterização química, física e biológica de bens culturais”, este artigo trata de como o uso de técnicas de caracterização pode ser feito para avaliar o impacto da composição de microambientes a bens culturais e de como essa avaliação pode auxiliar em sua preservação, utilizando-se de dois estudos de caso.

In this work the effect of relative humidity (RH) and formaldehyde (H 2 CO) concentration on Pb corrosion was investigated; a possible synergism between the aldehyde and CO 2 effects was also considered. Triphasic aqueous salt solutions were used to produce 54% and 75% RH that, together with the 100% RH condition, were combined with 0, 0.62, 55 and 2.0 10 2 mg m −3 formaldehyde concentrations to compose the wanted environments. The results pointed to the conclusion that even at low RH (54%) formates are produced at the metal surface as a consequence of formaldehyde adsorption, indicating that the aldehyde has an active role in Pb corrosion; formates were also observed at relatively low H 2 CO concentration (0.62 mg m −3 ). No synergism between formaldehyde and carbon dioxide were observed as demonstrated by the Raman images from a corroded Pb coupon, showing that formate and carbonate contributions to the corrosion products were not spatially related. When compared to other volatile organic compounds (VOCs), formaldehyde harmful effect towards metals is frequently underestimated and the results here reported clearly indicate that, even at low RH, its concentration in indoor environments, where it tends to be produced and accumulated, has to be carefully controlled.

Polychrome lead sculptures from Oratory Museum in Ouro Preto (Minas Gerais, Brazil) kept inside a glass showcase were severely degraded. The formed corrosion products were analyzed by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence (EDX) and Raman microscopy and proved to be mostly Pb carbonates and formates. Although carbonate is a very common finding in Pb atmospheric corrosion, Pb formates can be formed by the action of formic acid or formaldehyde, being their origin a key point to be investigated. Environmental simulations with Pb coupons exposed to possible sources of these volatile organic compounds led to the conclusion that the degradation process was caused mainly by the curing process of the painted showcase baseplate. However, cleaning products, which can also contain formaldehyde as preservative, proved to be potentially harmful to Pb, accelerating its corrosion. Esculturas policromadas de Pb do Museu do Oratório em Ouro Preto (Minas Gerais, Brasil), expostas em um mostruário de vidro foram severamente degradadas. Os produtos de corrosão foram analisados por difratometria de raios X (XRD), espectroscopia no infravermelho com transformada de Fourier (FTIR), microscopia eletrônica de varredura (SEM), fluorescência de raios X por dispersão de energia (EDX) e microscopia Raman, e constatou-se a formação majoritária de carbonatos e formiatos de Pb. Embora carbonatos sejam comuns na corrosão atmosférica de Pb, formiatos podem ser formados tanto pela ação de ácido fórmico quanto de formaldeído, sendo sua origem um ponto importante a ser investigado. Simulações ambientais com tiras de Pb expostas a possíveis fontes desses compostos orgânicos voláteis possibilitaram concluir que o processo de degradação foi causado principalmente pelo processo de cura da tinta utilizada na base do mostruário. Contudo, produtos de limpeza, que podem conter formaldeído como conservante, mostraram-se potencialmente capazes de causar danos a objetos de chumbo, acelerando sua corrosão.