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1.
《文物保护研究》2013,58(4):299-314
Abstract

Instrumental-based color matching using non-destructive reflection spectrophotometry can be used as an aid in pigment selection for inpainting. This is useful when metamerism is of concern, particularly in modern art where the number of colorants available to artists and conservators is quite large. Simplified methods have been developed for art conservation where a single tint of each pigment mixed with white is required to define a pigment's optical properties based on the single-constant form of Kubelka-Munk (K-M) turbid media theory. Theoretically, this simplification can lead to errors in pigment selection for dark colors and colors not containing a white pigment. Instead, the two-constant form of K-M theory can be used where the model assumptions more closely match the optics of inpainting materials. The two methods were compared using four acrylic emulsion paints with a range of pigment absorption and scattering properties. It was found that the simplified method was inadequate for paints with appreciable and spectrally selective scattering, and as a consequence, pigment selection may result in a greater number of pigments than actually required. It was also found that only two samples per pigment were required to implement the two-constant technique: the mass tone and a tint.  相似文献   

2.
The impact of the spectral composition of light on the discoloration of paint pigments has been investigated for the case of lead chromate sulfate, an unstable yellow pigment used by Vincent van Gogh and other painters. With LEDification, museum lighting is moving from using halogen to LED lamps. LED light sources have a significantly different spectral composition than halogen lamps. To understand the impact of these differences on pigment stability, the wavelength dependence of pigment discoloration was determined. Contrary to the expectation that lower wavelength photons induce more damage than higher wavelength ones, UV (394?nm), blue, and cyan light all lead to similar levels of discoloration of a pigment for the same level of radiant power. By understanding this wavelength dependence, it becomes possible to create white light LED lamps with a spectral composition tuned to minimize the degradation effect. An existing LED solution with a modified emission indeed resulted in 30% less color change in the experiment than halogen. Furthermore, a method is proposed to optimize the LED spectra by tuning to the properties of each specific artifact. Simulations show that this can reduce the damage of the light source by 45% in specific cases.  相似文献   

3.
《文物保护研究》2013,58(3):205-229
Abstract

The purpose of this study was to develop a method for the identification of synthetic organic pigments on the basis of colour reactions with four different chemical reagents: concentrated sulphuric acid, concentrated nitric acid, a mixture of concentrated sulphuric acid and concentrated nitric acid and, finally, a solution of potassium iodate in concentrated sulphuric acid. Colour reactions for a large number of synthetic organic pigments in the form of pure powdered material were recorded. It is shown that the colour reactions observed are in overall agreement with the chemical grouping of pigments (for instance, naphthol AS pigments or quinacridone pigments), i.e., pigments belonging to the same pigment group yield similar colour reactions. This fact is the basis for the construction of flow charts for identification. Tests performed on a number of artists' colours containing pigments in various binding media show that the binding media do not noticeably affect the colour reactions observed, making the flow charts useful for the identification of actual artists' pigments. A fifth chemical reagent, namely a saturated solution of potassium hydroxide in 96% ethanol, was tested and abandoned as a result of its instability, which resulted in severe problems with reproducibility, especially for certain pigment groups, for example the acetoacetarylide pigments.  相似文献   

4.
《文物保护研究》2013,58(1):95-97
Abstract

Acrylic polymer dispersions, regularly used as artists' media or varnishes, were monitored for the development of yellow discoloration under natural aging conditions for a period of two years. Films of a number of water-based acrylic artists' media were kept under visible light of either moderate (150 lux) or low (50 lux) intensity (cycled on 10 hours per day) and were compared to films kept in dark storage, which have been observed to yellow. Results after two years show that exposure to visible light at 150 lux effectively prevented film discoloration in a number of products, and seemed at least to slow the rate of yellowing in others. Exposure to low-intensity (50 lux) lighting was found to be less effective in preventing this yellowing.  相似文献   

5.
Elizabeth Cay (1771–1831), the grandmother of the Scottish physicist James Clerk Maxwell (1831–1879), was a talented amateur pastellist; several of her pastel portraits survive as does her set of pastels. She studied with Archibald Skirving (1749–1819), a Scottish miniature painter who later in life turned to larger-scale portraiture in pastel and served as drawing master to the Edinburgh elite. Cay's pastels are not fabricated sticks but consist of powdered pigment housed in various glass and ceramic containers and were apparently applied by stumps, still in her workbox, or brushes. The Cay color samples were identified by spectrographic analysis, polarized light microscopy, and microchemical tests which, in addition, indicated that a number of pigment mixtures present gave specific hues in keeping with earlier treatise accounts of the preparation of a pastel gamut for practical use. Elizabeth Cay's pastel workbox may be rare surviving evidence of one way, more common that we appreciate today, in which amateurs, and perhaps professionals, practiced pastel painting.  相似文献   

6.
《文物保护研究》2013,58(2):62-72
Abstract

Although smalt, a glass, might be expected to behave as a stable pigment, discolouration of smalt-containing paint layers has been observed. Early references from the literature are cited which mention the discolouration of smalt in oil media. Originally blue layers on paintings have changed into dull grey or greyish-green. Experiments suggest the following factors for this discolouration: low refractive index of the pigment compared with that of oil media; interaction of alkali content or cobalt content with oil and oleo-resinous media; the possibility of similar reactions with resin- or oil-resin varnishes in certain conditions. Discolouration may also occur if smalt is mixed with other pigments, or added as a drier or as an adulterant.

A proper understanding of the mechanism of the deterioration would require further research by more sophisticated methods.  相似文献   

7.
This paper describes the use of a customized algorithm for the colorization of historical black and white photographs documenting earlier states of paintings. This study specifically focuses on Pablo Picasso's mid-century Mediterranean masterpiece La Joie de Vivre, 1946 (Musée Picasso, Antibes, France). The custom-designed algorithm allows computer-controlled spreading of color information on a digital image of black and white historical photographs to obtain accurate color renditions. Expert observation of the present state of the painting, coupled with stratigraphic information from cross sections allows the attribution of color information to selected pixels in the digitized images. The algorithm uses the localized color information and the grayscale intensities of the black and white historical photographs to formulate a set of equations for the missing color values of the remaining pixels. The computational resolution of such equations allows an accurate colorization that preserves brushwork and shading. This new method is proposed as a valuable alternative to the use of commercial software to apply flat areas of color, which is currently the most common practice for colorization efforts in the conservation community. Availability of such colorized images enhances the art-historical understanding of the works and might lead to better-informed treatment.  相似文献   

8.
A treatment with projected light for Mark Rothko's Harvard Murals (1962) is proposed. The group of five paintings on canvas has changed color due to the presence of a fugitive red pigment and excessive exposure to natural light in a room with large windows. For the conservation of Rothko's Harvard room, it is brought into context within his other commissions and environments. The original color of the works is determined by the digital restoration of contemporary photographs. With a camera projector system a compensation image is calculated that is projected onto the original canvas resulting in a restored color appearance. This approach of inpainting with light is compared with considerations of cleaning and inpainting in conventional conservation treatments. Overall lighting and architecture including the unusual wall color carefully chosen by Rothko play a key role in the treatment of the Mural cycle as an environment.  相似文献   

9.
Summary

The composition and nature of the different sulfides which can occur on underground iron are reviewed with reference to the literature, together with the various corrosion reactions. The type of pyrites on fossils and minerals is also included. The experimental work involved goethites and magnetites reacting with damp hydrogen sulfide gas to give mackinawite, pyrite and/or greigite. These can react exothermically and may be pyrophoric. Methods to increase stability and reduce the danger of pyrophoric oxidation are discussed.  相似文献   

10.
《文物保护研究》2013,58(2):54-61
Abstract

Samples of pigments from excavated wall paintings of Vergina’s second tomb were analyzed by the non-destructive methods of X-ray fluorescence, X-ray diffraction and mineralogical microscopic examinations. The results showed that one type of blue pigment was used, the well-known Egyptian blue. The red pigments, except one which is haematite, are cinnabar (HgS), and the grey pigments are carbon. None of the black pigments contained manganese compounds.  相似文献   

11.
《文物保护研究》2013,58(4):156-158
Abstract

Framed and glazed prints have been found to yellow rapidly when on exhibition. It was found that the frames all contained the fungicide thymol. Experimental work has shown that the discoloration is caused by photoxidation. The discoloration was present in the paper and in the polymethyl methacrylate glazing. Mass spectroscopy has revealed the presence of a polymer of thymol; there was no evidence for the expected oxidation products.  相似文献   

12.
none 《文物保护研究》2013,58(1):42-57
Abstract

A wide-ranging sample set consisting of dry pigments, dyed textiles, organic and aniline-based dyes, gouaches and watercolors, fluorescent inks, and natural history specimens was exposed to light in air (20.9% oxygen) and near-anoxic environments. After a light dosage of approximately 17.5 Mlux-hours under controlled temperature and humidity conditions, 113 of 125 samples (90% of the sample set) were shown to exhibit less color change in a low-oxygen environment compared with its behavior in air. Thirty-nine percent of this subset displayed color change in anoxia that was between two and four times lower than that observed in air, whereas 47% showed color change in anoxia reduced by a factor of four or more. In contrast, six samples exhibited greater color change in anoxia than in air – these samples included Prussian blue watercolor (three samples), Antwerp blue watercolor, Verdigris dry pigment, and Fluorescent Yellow Winsor & Newton Gouache. Although the results from this small sample subset may cause concern when considering the use of anoxia in the conservation of cultural heritage, particularly for colorant systems whose behavior in anoxia has not yet been identified, this study demonstrates the overwhelming benefits of anoxic light exposure for the vast majority of samples investigated here.  相似文献   

13.
ABSTRACT

Twentieth century paints often contain titanium dioxide and zinc oxide based white pigments that can range from photostable to highly photocatalytic. Photocatalytic pigments can cause the degradation of paint upon UV exposure, whereas photostable pigments may be benign or can protect paintings from degradation. Hence, knowing whether or not a pigment is photocatalytic is of high importance for risk assessment and the subsequent decision making process concerning storage and exposure conditions of objects. Here we present a proof of principle, focused on titanium white paints, for an easy-to-use and low-tech application of a commercial photocatalytic activity indicator ink (PAII) on embedded paint samples or cross sections. This test determines, qualitatively, if a photocatalytic pigment is present in a white paint sample. The PAII paint sample staining application shows an obvious color change, within five minutes of UV irradiation, for paint samples containing photocatalytic pigments. A microscope with a camera and a UV source are the only necessary equipment for the application of this method. A quantitative image processing protocol is also proposed as an extension of the staining method by applying open source software analysis to measure the color change using photographs. The test was evaluated on reference paints with well-characterized pigments and applied on samples from modern paintings by Piet Mondriaan, Robert Ryman, and Lucebert, indicating the presence of harmful photocatalytic pigments in these cases. The novel application of a commercial ink on paint samples offers a simple test, not just for assessment of photocatalytic activity of titanium white pigments, but which may in future be applied for the detection of photoactive forms of zinc white and other potentially harmful semiconductor pigments in art objects.  相似文献   

14.
ABSTRACT

This paper is drawn from an empirical, ethnographic study of information and communications technologies (ICT) use among thirteen, low-income twelfth-graders attending a large urban high school and focuses on participants' ICT access in the school library. It examines how library staff members' cultural and gendered perceptions shaped ICT restrictions in ways that disproportionately impacted students of color, boys, and boys of color and how institutional factors helped to create conditions under which subjectivities served as guideposts for managing scarce resources. I argue that some restrictions were unfounded, unnecessarily impeded these students' ICT use and access and created avoidable tensions between students and library staff.  相似文献   

15.
ABSTRACT

A diverse workforce is important to librarianship. As a result, the recruitment of librarians of color has remained a priority; additionally, ensuring that those individuals are retained and advancing is of equal importance because it speaks to the profession's ability to maintain a diverse workforce. This article explores the interrelationship between retention and advancement for academic librarians of color working as middle managers. Through the use of narrative inquiry, the author found that several commonalities emerged among participants: the prevalence of internal promotions, lack of interest in senior leadership, and participation in library leadership institutes. The findings indicate that retention and advancement are two separate and distinct issues for librarians of color working as middle managers, with retention less of a concern. The findings also suggest that the relationship between the middle manager and his or her supervisor is critical to interest in advancement.  相似文献   

16.
ABSTRACT

Interlibrary Loan (ILL) is intended to supplement a library's collection, but often patrons submit requests for items already owned. An analysis of a large academic library's ILL requests shows that in most cases the cataloging of bibliographic records is correct, but patrons need instruction in bibliographic searches and ILL policies and procedures. An unexpected result of the study was a realization that patrons are confused by the way items are shelved in the various branches.  相似文献   

17.
《文物保护研究》2013,58(4):149-154
Abstract

The small areas of white metallic pigment seen on the south wall of J. M. Whistler's ‘Peacock Room’ in the Freer Gallery of Art are platinum; this has been used, with a yellow-brown ground, to overpaint a preceding layer of silver which, in one place only, is over a preceding layer of gold. The yellow metallic pigment is confirmed as gold and the blue colour of the south wall and elsewhere is based on Prussian blue. On a separate wood panel a green was tentatively identified as copper resinate, and iron-oxide-based pigments appear to be present. In all areas investigated a white, used as a ground and in admixture, was essentially lead white and calcium carbonate. The significance of these results is discussed briefly.  相似文献   

18.
《Communication monographs》2012,79(3):190-221

With an 1890 book called The Influence of Sea Power Upon History, Alfred Thayer Mahan had a profound and far‐reaching impact upon subsequent world events. In large measure, Mahan's effectiveness was derived from his style in discourse. Evidence for this assumption is found in the reactions of Mahan's readers, in their correspondence to him or about him. Analysis and synthesis of those situationally bound responses to discourse account for a rhetorical function of style in language as para‐message conducing to ethos.  相似文献   

19.
《文物保护研究》2013,58(4):265-273
Abstract

This paper reports on the results of experiments to test for visual changes to paint systems after biocidal treatments, using a statistical binary procedure. Four biocides were selected, two of which are fungicides—a quaternary ammoniumorganotin mixture (BioMet 66®)in distilled water and an orthophenylphenol (Lysol®) in a spray— and two of which are fumigants—sulfuryl fluoride (SO2F6), a gas (Vikane®), and nitrogen gas (N2) (as an anoxant). The procedure used to assess the effect of the biocidal treatments was a random field visual scoring regimen by two paintings conservators. The tests were conducted on 30 combinations of linen, rabbitskin glue size, lead white oil ground and oil-based paints. The visual assessment procedure provided information on color change, gloss change, blanching, topography change and precipitation. The results indicated that Vikane adversely affected 10 of 11 pigment systems; Lysol adversely affected six of 11 pigment systems; BioMet 66 had a minor effect on four of 11 pigment systems; and nitrogen had no visible effect on any sample. The visual technique provided a quick and broad method for assessment of non-subtile visual changes.  相似文献   

20.
《The Reference Librarian》2013,54(82):157-169
Abstract

During the summer of 2002, Cornell University Library implemented the Cornell University Library Junior Fellows Program-an initiative aimed at introducing high school students of color to academic libraries and librarianship. The six-week program was developed in response to the need for innovative approaches to the recruitment and retention of people of color to the academic library profession. Additionally, the program sought to support the academic achievement of minority students through involvement in research and technology training opportunities. This paper outlines the program's curriculum, performance outcomes, and challenges, and includes discussion of the need for similar programs or initiatives to be designed and implemented at other libraries.  相似文献   

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