Early aqueous dispersion paints: Portuguese artists’ use of polyvinyl acetate, 1960s–1990s

Abstract

The ageing of poly(vinyl acetate), PVAc, paints was assessed in works by Ângelo de Sousa and Joaquim Rodrigo. The materials and techniques of the artists were studied through interviews and by chemical analysis. They were both using PVAc in 1961, preparing their own paints by mixing commercial PVAc emulsions with selected colorants. It is shown that in most cases the emulsion employed was based on a PVAc homopolymer and that the paints are in good condition with no signs of deterioration. Finally, this study allowed a comparison to be made between paint samples aged naturally and those aged under artificial conditions. This means that these artificially aged samples may be used as reference materials for PVAc paintings. Both sets exhibit molecular infrared fingerprints that are undistinguishable from an unaged PVAc, suggesting little chemical degradation over 50 years of natural ageing.     

Yellowing of Oil-Based Paints

Summary

The cause of yellowing of oil-based paints has been investigated by analysing drying oils simultaneously by iodometry (to determine the degree of oxidation) and by colorimetry. It was found that yellowing of drying oils can be attributed to co-oxidation reactions of contaminants. Yellowing level is closely related to the extent of drying and appears to be unaffected by increase in temperature, the addition of driers, or linolenate content.     

The materials and techniques used in the paintings of Francis Bacon (1909–1992)

Abstract

Materials from 38 paintings by Francis Bacon (1909–1992), including 21 complete works and 17 partially destroyed canvases are investigated. Observations are made of the artist's technique and details are compiled of the supports used. Samples of paint and priming were taken for analysis using polarized light microscopy, Fourier transform infrared spectroscopy (FTIR), gas chromatography–mass spectrometry (GC–MS), pyrolysis–GC–MS (Py–GC–MS), and scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM–EDX). Analysis of priming layers appears to show that the priming composition correlates well with particular ranges of dates. A fairly limited range of materials are found, with many of the same pigments found in works spanning Bacon's career, though other pigments were introduced at different stages in his career. Oil paints were used consistently for the painting of figures, but household paints were increasingly used in backgrounds from the 1960s onwards. A variety of different synthetic media are found in later works, including household acrylic paints and spray paints. Increased knowledge of Bacon’s materials is expected to be of great value to conservators caring for the work of this highly significant artist, and is already helping in the authentication of works attributed to him.     

Microbial calcification of gypsum-rock and sulfated marble

Abstract

A broth containing the sulfate reducing bacterium Desulfovibrio desulfuricans was used to treat samples of reagent calcium sulfate, gypsum-rock specimens, fragments from a marble monument with a black weathering crust rich in gypsum, and a marble monument with similar crust. Calcite was found to have formed on all treated surfaces suggesting that this microbe has the potential to clean crusted marble monuments whilst also regenerating calcite, the parent mineral of the marble.     

The analysis of synthetic paints by pyrolysis–gas chromatography–mass spectrometry (PyGCMS)

Abstract

This paper describes the application of pyrolysis–gas chromatography–mass spectrometry (PyGCMS) to the characterization of an extensive range of synthetic paint types. Household and industrial paints, both of which have been formulated with polymers such as alkyd, polyvinyl acetate (PVA) and nitrocellulose, are included in this study, in addition to the acrylic solution and acrylic emulsion paints that were made specifically for the artists' market. The pyrograms obtained by PyGCMS were characteristic to each paint type and their principal diagnostic features are discussed. Apart from using the mass spectra produced by electron impact (EI) to confirm the identity of every peak, two additional analytical features of the mass spectrometer were shown to be particularly useful in this study. Chemical ionization (CI) was used to assist with the identification of unknown peaks through molecular weight determination. Selected ion current (SIC) monitoring, where the mass spectrometer only scans for specific masses, was successfully used for the detection of peaks of low intensity or those hidden by a more abundant material with a similar retention time.     

A PRELIMINARY NOTE ON THE USE OF ADHESIVES AND FILLERS IN THE RESTORATION OF ANCIENT MATERIALS WITH SPECIAL REFERENCE TO GLASS

Abstract

We have reacted Georgia marble in sulfur dioxide (SO₂) enriched atmospheres and calculated the reaction rate constant. This constant was derived from surface reduction data, obtained by leaching thereaction product from samples exposed for different periods of time. Application of this constant to marble weathered in known ambient levels of sulfur dioxide (SO₂) and relative humidity, allows the prediction of the thickness of the resulting gypsum crust formed over a given period of time. We have found that the crust grows outwards due to calciumions which migrate from the interior and then react with sulfur dioxide at the sample surface. Thus, anytreatment of the sulfated marble should include the considerations that the crust only masks the marble surface and is not an integral part of the original sculpture, and that cavities exist in the underlying layer of marble from which the calcium ions were selectively depleted.     

Sanguine Paint: Production,Characterization, and Adhesion to the Glass Substrate

ABSTRACT

For centuries, the only painting materials used in stained-glass production were grisaille and yellow (silver) stain. At the end of the fifteenth century, stained-glass painters began to use a new material, sanguine. This paint is mainly produced with iron oxide particles, usually haematite, and allowed to obtain a colour that can vary from yellowish to brownish-red due to the nature and particle size of the iron oxide. A translucent sanguine was mostly applied as flesh and hair colour, with an opaque sanguine used for drapery, architectural motifs, and heraldry. The main goal of this study is to investigate the relationship between historic sources on the preparation and use of sanguine from the fifteenth to the nineteenth centuries and the evolution evidenced in the recipes regarding the production method. Representative recipes from several centuries (sixteenth to nineteenth centuries) were selected and reproduced for this study. These reconstructions were thoroughly characterized using X-ray powder diffraction, optical microscopy (OM), and fibre optic reflectance spectroscopy (FORS). The OM and FORS data were correlated with historic sanguine paints applied on historic stained-glass. The similarities and differences between historic and reconstructed paints are presented. The study of reconstructed sanguine’s adhesion to glass using cross-cut testing was also performed, revealing that the adhesion is strongly influenced, not only by the binder, but also by the composition and morphology of the sanguine paint.     

Evaluating Single- and Two-Constant Kubelka-Munk Turbid Media Theory for Instrumental-Based Inpainting

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.     

Characterization of organic azo-pigments by pyrolysis–gas chromatography

Abstract

Pyrolysis–gas chromatography was applied to the characterization of synthetic organic pigments. On pyrolysis, azo pigments and phthalocyanine blue yield characteristic fragments. These pyrolysis products were identified, and the mechanism of decomposition was studied. In the case of paint samples, the main pyrolysis products derive from the medium, although the presence of additional peaks enables azo pigments and phthalocyanine blue to be characterized. Some examples of the analysis of artists' paints are given and the peaks are identified. The main limitation of this technique is that it is impossible to detect chemically and thermally stable pigments, or inorganic components.     

THE SCIENTIFIC EXAMINATION OF THE POL YCHROMED SCULPTURE IN THE HERLIN ALTARPIECE

Abstract

An account is given of the examination of the polychromed sculpture in the Hedin altarpiece (1466) in Rothenburg old T. (W Germany). Analytical methods used, such as microscopy, wet chemical analysis, infrared spectrophotometry, thin-layer chromatography and gas-liquid chromatography are briefly described. Criteria for identification are summarized. Pigments identified are azurite, indigo, verdigris, green earth, madder, vermilion, red lead, lead white and carbon black. The binding medium is glue in matt areas. In other parts paints are mostly based on a resinous medium with varying amounts of oil. The materials identified in the applique relief brocades are compared with recipes described in the Liber Illuministarius from Tegernsee. Silver foil is used in producing translucent paint.     

Determining The Presence of Photocatalytic Titanium White Pigments via Embedded Paint Sample Staining: A Proof of Principle

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.     

TWO ABORIGINAL ROCK ART PIGMENTS FROM WESTERN AUSTRALIA THEIR PROPERTIES,USE, AND DURABILITY

Abstract

Naturally occurring pigments used by Aborigines in rock paintings have been collected in Western Australia. They area red pigment (mainly hematite, Fe₂O₃)(from a red ochre mine worked until historic times by Aborigines, and a white pigment (huntite, Mg₃Ca(CO₃)₄) which is still collected and used by Aborigines. Samples were also taken from rock paintings in which these pigments were used or were thought to have been used. The pigment samples were analysed to establish chemical, mineralogical, and physical properties. The paint samples were examined microscopically and with an electron probe to study their relationship with the rock surface and with other paint layers. The relationship between the pigments’ properties and their durability is discussed.     

Fungal bioreceptivity of Japanese tissue papers treated with plant dyes,watercolours, and acrylic paints in paper conservation

Despite substantial literature on the dyeing of textiles, there is a lack of research about colouring Japanese mending papers (tissue papers) used for paper conservation purposes. This study investigates the fungal bioreceptivity of Japanese tissue papers after they have been treated with various dyes and pigments. A variety of toning materials including plant dyes, watercolours, acrylic paints, inks, pastels, gouaches, and colour pencils are commonly used by conservators for paper toning purposes. In this study, two Japanese tissue papers (Yukyu-shi and Sekishu Mare) were treated with selected plant dyes, watercolours, and acrylic paints and then inoculated with fungal species. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the DNA from Aspergillus niger and Penicillium rubrum as a proxy for fungal species abundance before and after inoculation and artificial moist heat ageing. qPCR primers which were universal for fungi amplified DNA from papers inoculated with A. niger and P. rubrum and these species were found to grow less on treated Sekishu Mare and Yukyu-shi papers compared with untreated papers. Sekishu Mare papers treated with artists' acrylic paints were found to be more resistant to fungal growth than similarly treated Yukyu-shi papers. This study suggests that for the best long-term preservation outcomes for paper materials in archives, libraries, galleries, and museums, acrylic paints generally perform better in conservation terms than most plant dyes and watercolours, although most colourants displayed some bioinhibition.     

Investigation of the materials found in the studio of Francis Bacon (1909–1992)

Abstract

The investigation of materials found in Bacon's studio is reported. The contents of the studio are examined and interpreted to identify the materials and colours most favoured by Bacon, and the range of media used. A small number of colours appear to have been heavily used. Some objects used as tools in the painting process are also investigated and explain textures seen in paint in his works. Samples of selected materials from the studio are analysed to identify the components of paints (pigments, extenders, and binders) used by Bacon. This investigation is part of a wider project examining his materials and techniques. The analytical information obtained here from the studio helps to clarify the statements made by Bacon in interviews regarding his use of materials and is proving useful in the identification of materials in his paintings, in order to help with the conservation and authentication of his works.     

Materials and techniques in the pictorial oeuvre of Lucio Fontana

Abstract

The painting materials used by Lucio Fontana were investigated through the analysis of 28 Spatial Concept works created between the early 1950s and the artist's death in 1968. The pictorial media were analyzed by means of numerous techniques including Fourier transform infrared spectroscopy, pyrolysis-gas chromatography–mass spectrometry, scanning electron microscopy, and X-ray fluorescence. This study has provided a more complete understanding of the artist's technique, as it was found that Lucio Fontana had already begun experimenting with new synthetic pictorial and binding media such as alkyds and polyvinyl acetates at the beginning of the 1950s, and polyesters during the early 1960s. Although he never abandoned the use of commercial oil paints, Fontana's application of these new materials continued in an infinitely varied search for innovative expressive effects. The characterization results explain the physical and mechanical properties of the paint layers, and may be correlated with the conservation state of the works analyzed. All the results have been compiled and are discussed together with the artist's practices and their evolution over time.     

Visual effects of selected biocides on easel painting materials

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.     

IFLA and other International Library Associations,Institutions and Organizations

Column Editor's Notes

This workforce column, guest written by Jill Mierke, evokes memories of the saying, you are not alone. The challenges of workforce and workplace leadership for any library chief executive officer are many and varied. We come to those roles usually as experienced (if not seasoned) professionals, but we do not always have the theoretical grounding and specific professional practice experience a dedicated human resources professional might bring to the organization. A Master's in library and information sciences qualification is no guarantee that you will have the requite knowledge, skills, experience, and abilities to be a good people manager or a strategic leader of the library workforce. This article paints a compelling picture of what success for library human resource management and leadership can look like, through the lens of an experienced and seasoned human resources professional. Recent workforce research is telling us there are many roles within our libraries that are now being successfully filled by “other” professionals. In our ever changing and dynamic information landscape, the human resources strategic advisory role is one of them.

As always, I invite further contributions to our ongoing discussion! Please submit articles for this column to the editor at vicki.williamson@usask.ca     

English Artists' Paper,Renaissance to Regency

Abstract

Oil paints dry by polymerization. This 'drying' process may be substantially complete and the surface of the paint film dry to the touch within weeks, but measurable changes continue for years. Other, slower processes also continue, primarily hydrolysis of glyceride esters. This produces carboxylic acid groups as either free fatty acids (in the case of acid groups that have not reacted otherwise) or acid groups bound to the crosslinked oil matrix (in the case of acid groups that have engaged in polymerization reactions). These may react with pigments to form carboxylate salts (called soaps in the case of a fatty acid). These changes affect the physical properties of the paint and the way that conservation treatments affect it. This paper examines the extent of hydrolysis and soap formation in some naturally aged drying oil and paint films, the extractability of these materials in organic solvents, and measured and predicted changes over time in the physical properties of naturally aged paint films. Long-term physical and mechanical changes due to aging are minor compared to those produced by overcleaning or excessive exposure to heat.     

Detection and Virtual Reconstruction of the Original Form of a Rock Relief,Lost in Part by Water Erosion

ABSTRACT

Historic rock reliefs are magnificent monuments that represent special events of the past. Due to exposure to the natural environment, these monuments are affected by natural and human erosion mechanisms. Many of them have disappeared over time and are no longer recognizable. This research seeks to find a way to understand the initial shapes of the rock reliefs that have been exposed to steady and prolonged erosion. For this purpose, a case study was selected in southern Iran that has been damaged over hundreds of years by a stream of water and has partially disappeared. The water flow has caused a groove to be formed along the cliff and apparently a strip of the relief has disappeared. Documenting the inner surface of the groove revealed that this surface is not smooth and there are still remnants of unclear reliefs in eroded sections. By examining the erosion effects on initially vertical smooth sections, it was possible to arrive at a formula to determine the damage caused by the water flow on cliffs. Based on this, it was determined to what extent the water flow had reduced the amount of rock at each height. Accordingly, each level of the damaged relief was virtually moved forward to the same extent. In this way, parts of the disappeared rock relief were virtually rebuilt. The results of this study showed that by measuring the gradual and continuous erosion factors and determining the extent of damage, the original shape of the damaged rock reliefs could somehow be reconstructed.     

Soviet Rock Collection and International Counterculture Archive at the Global Resources Center of the George Washington University Libraries

ABSTRACT

This memoir is my personal story about how I created and came to curate on the International Counterculture Archive collection, which is held in the Global Resources Center of the George Washington University’s (GWU) Gelman library. The first person narrative relates my first encounters with Soviet rock culture and describes how I turned my initial interest into a Ph.D. dissertation on the subculture of Soviet hippies and traditions of Soviet rock music, which subsequently led to my later work as a librarian and curator. I tell the story of my initial encounters with the members of Soviet/Russian rock music subculture and other countercultural personalities and activists during my first trip to Moscow in 1993 to collect samples of Soviet rock music recordings and rock music zines for the European Division of the Library of Congress. During this formative trip I met with a number of counterculture producers and collectors who were instrumental in helping me build the International Counterculture Archive. Upon leaving the Library of Congress, I continued collecting Soviet/Russian countercultural materials on behalf of the Global Resources Center of GWU’s Gelman Library. I talk about the process of creating the Archive at Gelman library, about bureaucratic and financial aspects of this work, and about my many acquisition trips to Moscow, former Soviet republics, and East Central Europe. Much of the narrative centers on my work with Russian collectors and content producers and describes the type of materials that are included in the collection. I also describe how I built the collection of historical Soviet/Russian rock music recordings, focusing on the phenomenon of Soviet/Russian rock music zines and the history of the unique zine collection within the International Counterculture Archive.