As part of an undergraduate summer research project in vibrational spectroscopy, the micro-Raman spectra of synthetic samples of the famous artists' pigments, chrome yellow and Maya blue, were ...investigated at various temperatures to determine their long-term stability with respect to dramatic changes in temperature. Synthetic chrome yellow was examined from −150°C to 500°C. Synthetic Maya blue was studied from ambient temperature up to ∼200°C, when the Raman signals became swamped by the strong fluorescence from the sepiolite clay in which the indigo dye was encapsulated. Both pigments proved to be extremely stable with respect to significant changes in temperature, which presumably accounts in part for their long-term use in artwork.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This lecture text shows what fascinating tasks analytical chemists face in Art Conservation and Archaeology, and it is hoped that students reading it will realize that passions for science, arts or ...history are by no means mutually exclusive. This study describes the main analytical techniques used since the eighteenth century, and in particular, the instrumental techniques developed throughout the last century for analyzing pigments and inorganic materials, in general, which are found in cultural artefacts, such as artworks and archaeological remains. The lecture starts with a historical review on the use of analytical methods for the analysis of pigments from archaeological and art objects. Three different periods can be distinguished in the history of the application of the Analytical Chemistry in Archaeometrical and Art Conservation studies: (a) the “Formation” period (eighteenth century–1930), (b) the “Maturing” period (1930–1970), and (c) the “Expansion” period (1970–nowadays). A classification of analytical methods specifically established in the fields of Archaeometry and Conservation Science is also provided. After this, some sections are devoted to the description of a number of analytical techniques, which are most commonly used in routine analysis of pigments from cultural heritage. Each instrumental section gives the fundamentals of the instrumental technique, together with relevant analytical data and examples of applications.
A description is given of James Clerk Maxwell’s strategy, in his early study of the additive mixing of light from coloured samples. He used the scattered daylight from known areas of card coated with ...artists’ pigments. Vermilion, emerald green and ultramarine were the optimum choice of standards for red, green and blue, respectively. They suited Thomas Young’s description of colour vision. Maxwell’s design of an analogue device – his ‘colour top’ – for varying the areas of the contributing pigments was remarkably simple. His meticulous observations with it allowed him to substantially further the understanding of perception of colour at the time, mid-19th century. The interpretation of a few very basic spectroscopic measurements on sunlight reflected from pigments are in line with Maxwell’s conclusions.
An Odyssey Through Time at EMPA Marianne Senn; Wim Devos; Walter Fasnacht ...
Chimia,
01/2001, Letnik:
55, Številka:
11
Journal Article
Recenzirano
Odprti dostop
For years EMPA has made many contributions to research on historical materials and their manufacture and conservation in archaeology, restoration and the preservation of historical monuments; areas ...that are somewhat exotic for a materials testing and research institute. This involves complex, preferably non-destructive investigations on objects that are often very valuable by means of organic and inorganic analysis methods. The emphasis is on investigations of paints and varnishes on paintings and metals such as gold, silver, copper, bronze and iron. The analysis of various materials and the associated problems are illustrated by a range of examples.
The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second ...half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2− moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type.
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•Single crystal X-ray structure analysis of the artists' pigment zinc yellow.•Characterisation of zinc yellow by Raman, SEM-EDS, ATR-FTIR and PXRD.•Discovery of a unique structure among chromate based pigments.
•Lakes of Naphthol Green B (Acid Green 1, Pigment Green 12, C.I. 10020) identified for the first time as artist's pigment in water and oil colours produced between 1910 and 1932.•Comprehensive source ...research on the dyestuff's and lake's history of production and fastness properties.•Reference data for its non-destructive or minimally-invasive analytical identification by Raman, SERS, FTIR, UV/VIS/NIR and XRF spectroscopy.
The synthetic nitroso dyestuff Acid Green 1 (hereafter AG1, C.I. 10020) and its lake (C.I. Pigment Green 12, hereafter PG12), today known under the trade name Naphthol Green B, was identified for the first time on six historical colour charts of commercial brands of artists’ paints. These comprise water and oil colours produced between 1910 and 1932 by the companies Winsor & Newton (London), G. Wagner (Hannover), Fr. Schoenfeld (Düsseldorf), Redeker & Hennis (Nürnberg) and Talens & Zoon (Apeldoorn). Because the use of AG1 (first synthesis in 1883) is well-known for textile dyeing, but not at all as a lake pigment for artists’ paints, these findings stimulated a comprehensive source research on the early production history, fastness properties and acceptance of the lakes of AG1 in the chemical and paint-technological literature from its invention to c. 1950. To summarize the findings, lakes of AG1 are regularly mentioned for paint purposes soon after the dyestuff's invention, mainly for house paints, paints for wall papers or as pigment for printing inks. In 1892, a lead lake of AG1 is described explicitly also for artists’ paints and a certain use in artists’ water colours, but also oil paints of higher quality could be proved until at least the 1930ies by the source research presented here. However, the pigment's fastness to light is unsatisfactory according to modern standards, and lakes of AG1, since 1956 denoted as PG12 (barium lake), are no longer of relevance in artists’ paints. It was presumably replaced by more stable organic green pigments such as those from the copper phthalocyanine group that have been introduced since the mid-1930ies. In this work, the non-destructive or minimally invasive analytical identification of AG1/PG12 in works of art is shown to be possible by Raman spectroscopy, SERS, FTIR and/or UV/VIS/NIR reflectance spectroscopy, accomplished by XRF for the lake substrate characterisation. Reference spectra of modern and historical specimens of AG1 (as lake and dye) produced in 1893 and 1900 are also presented here. Knowledge of the application and chronology of this today almost unknown pigment in art is of importance e.g. for dating purposes in authentication cases as well as under preventive conservation aspects, e.g. to define appropriate conditions for lightning conditions.
Copper phthalocyanine (CuPc) provides the most important blue and green pigments from the 21st century artists’ paints. This paper focuses on the blue pigments of CuPc, which are referenced in the ...Colour Index as PB15. The employment of PB15 as artists’ pigments since the very beginning until now is summarized through archives of artists’ color makers and current color charts. Moreover, for the first time, a review of the cases of PB15 identifica- tion encountered in the field of cultural heritage is presented. For each case reported in this study, the analytical methods that allowed identifying the blue pigment are specified. The significance and the relevance of various destructive and non-destructive methods, for this topic in particular are also discussed. Finally, the implications of PB15 in common conservation prac- tices are outlined.
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