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- Em meses de inverneira, histórias à lareira : Provérbios e dizeres enquanto transmissores de valores culturais e de identidade.Publication . Sol, HermíniaA tradição oral, enquanto objecto passível de ser teorizado e analisado cientificamente, ocupa ainda um espaço muito limitado no meio académico. Numa tentativa de romper com este estado de coisas, este artigo pretende reflectir sobre o papel que os provérbios e dizeres têm na perpetuação de certos valores culturais e nacionais. Para tal irá abordar a natureza didáctica destes dois fenómenos comunicacionais enquanto compromisso com as culturas de onde emergem. À luz do trabalho de Durkheim e de Vansina, irá explorar de que forma é que este género de produções anónimas contribui para a criação e manutenção da memória colectiva de uma dada comunidade. Traçará, também, alguns paralelos entre provérbios nacionais e seus congéneres europeus, no sentido de demonstrar que estes terão servido de veículo para o intercâmbio de ideias. Por último, fará menção a alguns projectos em curso que visam instigar a preservação e transmissão de aspectos do passado através da tradição oral.
- Clays from Vila Nova da Rainha (Portugal): Appraisal of their relevant properties in order to be used in construction ceramicsPublication . Coroado, João; Ferraz, Eduardo; Gomes, Celso F.; Rocha, FernandoThe clay deposit of Vila Nova da Rainha (VNR) is included in the lithostratigraphic forma tion named “Argilas de Tomar”, and is located at the lower section of the Tert iary Tagus’ river basin. Clay from one quarry is being extracted for the production of construction ceramics. In this work the firing transformations undergone by VNR cl ays containing quartz, alkaline feldspar, iron oxy-hydroxides, and clay minerals have been studied. Ca rbonates have not been identified in thes e raw materials. The clay layers can be subdivided in three groups based upon composition and ceramic properties. The first group, VNR0, is represented by smectite-kaolinite sandy-silty clay, the second group (VNR1 and VNR2) corresponds to illite-kaolinite bearing clay and the third group (VNR3 and VNR4) is represented by illite-smectite silty clay. The firing process involves the formation of hematite and mu llite both influencing the technical properties of the fired products. With regards to the ceramic properties assessed at 1100 ºC the first group showed the lowest total shrinkage value (7.35 %) the highest water absorption value (12.2 %) and the lo west mechanical bending strength value (12.0 MPa); the same properties assessed in the second group provi ded the highest firing shrinkage values (7.0-5.0 %), the lowest values of water absorption (0.1-0.2 %) and relatively high mechanical bending strength values (47.8-48.0 MPa); the third group showed firing shrinkage values within the range 3.5-4.2 %, water absorption values within the range 1.4-4.5 %, and the highest mechanical bending strength values (49.2-52.0 MPa). The results of the ceramic properties being appraised indicate that the raw materials being studied are suitable for the production of high-quality construction ceramics, such as brick, roof tile and rustic floor tile.
- Manufacture of Ceramic Bricks Using Recycled Brewing Spent KieselguhrPublication . Ferraz, Eduardo; Coroado, João; Silva, Joaquim Pedro; Gomes, Celso; Rocha, FernandoIn the brewing process, kieselguhr performs as a filtration medium and one generated by-product is a sludge containing kieselguhr, which is mainly composed of fragmented diatom frustules associated to organic material retained during the clarification process. The physic-mechanic tests were performed on assemblages with brick composition and brewing spent kieselguhr containing 3, 9, and 15 wt% incorporation levels of sludge, being extruded and dried (105ºC) before being submitted to slow firing at 900ºC, 950ºC, and 1000ºC. The obtained results showed that, even when at its maximum incorporation level, the spent kieselguhr for all firing temperatures do not cause important losses on the properties exhibited by the clay paste without kieselguhr incorporation and the best incorporation levels are 4.2 wt% when fired at 900ºC, 9.8 wt% when fired at 950ºC, and 13.4 wt% when fired at 1000ºC. When fired at 950ºC, 15 wt% addition of spent kieselguhr increased by 27% the open porosity and decreased by 10% the bulk density of the brick paste. Furthermore, physic-mechanic tests and ecotoxicity evaluation on semi-industrial brick manufactured with 9 wt% of brewing spent kieselguhr were accessed. The results do no show any constrain concerning mechanical properties, and the ecotoxicity evaluation shows the safety of the brewing spent kieselguhr incorporation in ceramic products.
- Comparative study of washing treatments for pastel drawingsPublication . Lory, Vera; Figueira, Francisca; Cruz, António JoãoA treatment procedure for pastel drawings, developed at the Portuguese Institute of Museums and Conservation (IMC), involves alkaline blotter washing in a humidifying chamber. This method is compared with three other techniques outlined in the literature: immersion in cold water, a combination of water mist and suction table treatment, and ultrasonic mist combined with a dry blotter support. The study applied these four treatments to both non-aged and aged test samples, encompassing three paper types and four pastel sticks, totaling 120 samples. The effects of these treatment methods were assessed using six semi-quantitative parameters determined by visual observation (i.e., lateral pigment movement, paper staining, pigment loss, decrease in color intensity, darkening, and change of hue). Additionally, three semi-quantitative parameters were evaluated through optical microscopy and scanning electron microscopy (pigment agglomeration, compacting, and penetration into the paper support). The findings indicate that the IMC method may not be suitable for treating pastel drawings executed on papers with low porosity. However, among the tested methods, it proves to be the most advantageous technique for treating pastel drawings executed on velour paper—the prevailing type of carrier for pastel drawings treated over the years at IMC.
- Conservation Publications - IIC member's reviews of international periodicals: PortugalPublication . Cruz, António João
- Spent brewery grains for improvement of thermal insulation of ceramic bricksPublication . Ferraz, Eduardo; Coroado, João; Gamelas, José; Silva, Joaquim Pedro; Rocha, Fernando; Velosa, Ana LuísaOne by-product of the brewing process is a waste containing spent grains (barley malt and maize grits). In the brewing process, this cake is composed mainly of organic matter containing high fiber content, provided by the separation of suspended particles through wort filtration. The study presented here was carried out to assess if the spent brewery grains could be recycled through their incorporation in a paste used in the manufacture of ceramic bricks, and how such incorporation affects some of the physical properties, namely mechanical strength, porosity, and thermal conductivity of the ceramic material. The main objective of the study was to decrease the thermal conductivity of the ceramic paste without significant losses of the mechanical strength of the final product. Spent brewery grains (SBG) characterized by powder X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, thermogravimetry, differential scanning calorimetry, and heat of combustion were used as an additive (pore-forming agent) to a brick paste, characterized by powder X-ray diffraction, particle-size analysis, mechanical strength, plasticity index, and thermal conductivity determinations. Powder mixtures obtained by addition of 5, 10, and 15% by weight of dry SBG to brick raw material (SBG-to-brick paste weight) were assembled. The powder mixtures were extruded and the green probes were dried (105°C) before slow firing at 900, 950, and 1,000°C. Drying and firing shrinkages and mechanical bending strengths were investigated in addition to bulk density, open porosity, water absorption, and thermal conductivity of the fired samples. The mixture of ceramic paste with SBG fired up to 900°C with an incorporation of SBG of 5% by weight was found to reach a compromise between the highest mechanical bending strength (15 MPa) and the lowest thermal conductivity (0.46 Wm−1K−1). When compared with the ceramic paste without SBG incorporation, a diminution of 12 and 28% of the values of these properties, respectively, was obtained.
- Caracterização através de análise química da escultura portuguesa sobre madeira de produção erudita e de produção popular da época barrocaPublication . Barata, Carolina; Carballo, Jorgelina; Cruz, António João; Coroado, João; Araújo, Maria Eduarda; Mendonça, Maria HelenaMaking use of several analytical techniques, four erudite and four popular Portuguese baroque wooden sculptures were studied. The materials and techniques employed were identified and the relationship between their artistic quality and the materials used was investigated. In general, the pigments were common at the time, but one pigment discovered in the beginning of the 18th century and two rare arsenic pigments were also identified. In popular sculptures cost-saving was detected, particularly concerning the gold leaf. Regarding some technical procedures identified, recommendations found in historical documents did not seem to have been entirely followed, neither in erudite nor in popular sculptures.
- Scientific study of an 18th century portuguese painting on canvas and their old restoration: PROBLEMS of date and authenticity of the current imagePublication . Cruz, António João; Rego, CarlaA Portuguese painting of the 18th century, from the collection of the National Library of Portugal, restored in 1864, was studied with the aim of better understanding the practice of restoration in Portugal in the late 19th and early 20th centuries. Initial observations suggested that it had been subjected to significant changes, due to the existence of an extensive decorative bar at the bottom of the painting and an inscription with calligraphy that seemed to suggest being of the 19th century. However, the scientific study carried out with the use of a set of analytical techniques leads to the conclusion that, essentially, the current image is consistent with the original image, although a thick layer of varnish and several localized repaints were observed. However, the inscription does not seem to be original.
- Problems of Analysis by FTIR of Calcium Sulphate-Based Preparatory Layers: The Case of a Group of 16th-Century Portuguese PaintingsPublication . Melo, H. P.; Cruz, António João; Candeias, A.; Mirão, José; Cardoso, A. M.; Oliveira, M. J.; Valadas, S.This paper provides a contribution to FTIR analysis of calcium sulphate-based grounds of paintings when a mixture of compounds with different degrees of hydration is present. The study is based on the analysis with that technique, electron microscopy coupled with energy-dispersive X-ray spectrometry and X-ray diffraction of both the grounds of 16th-century Portuguese paintings and reference samples prepared with anhydrite and calcium sulphate dihydrate bound in an animal glue solution. It is shown that the interpretation of the degree of hydration of calcium sulphate ground samples using FTIR cannot be based solely on the study of the hydroxyl bands, as is usual in routine work, but that small deviations of the S–O vibration bands are an important indicator of the presence of anhydrite in the grounds.
- An insight into the surface properties of calcined kaolinitic clays: The grinding effectPublication . Gamelas, José; Ferraz, Eduardo; Rocha, FernandoThe present work aimed characterizing in a systematic way the surface of metakaolinitic materials produced by calcination of a kaolinitic clay at different temperatures and to study the effect of grinding on the surface properties of metakaolinitic materials. Using X-ray photoelectron spectroscopy, it was found for all materials a Si/Al atomic ratio close to 1, confirming the presence of the 1:1 clay structure. By inverse gas chromatography, an increase of the Lewis basic properties of the surfaces of metakaolinitic materials in comparison to the original clay was found, which was due to the condensation of hydroxyl groups in the structure of the clay. The grinding of the metakaolinitic materials afforded a decrease of the dispersive component of the surface energy () as well as an increase of the specific interaction with sterically hindered molecules, caused by the diminishing of the materials surface nanoroughness. The Lewis basic properties of the materials surface also increased with grinding. Noticeably, for all studied materials a good inverse relation could be found between the and the specific interaction of trichloromethane (but not with dichloromethane), showing the importance of surface nanoroughness on the adsorption process of bulky molecules.