Gillian Osmond

Zinc white: a review of zinc oxide pigment properties and implications for stability in oil-based paintings

Abstract Zinc oxide became a frequent component of 20th-century paints following its first commercial availability in the previous century. Aspects of zinc oxide pigment production and paint formulation which influence the reactive tendencies of zinc oxide in oil-based paints are reviewed. Particular attention is given to the formation and aggregation of zinc soaps which have been linked to deterioration in paintings. Pigment particle properties, fatty acid profiles, paint additives and environmental conditions are all significant factors.

A study of zinc soap aggregates in a late 19th century painting by R.G. Rivers at the Queensland Art Gallery

Abstract Metal soap formation in paintings has been implicated in a serious deterioration phenomenon. The present study documents zinc soap aggregates observed in a late 19th century painting by R. Godfrey Rivers. Optical microscopy and scanning electron microscopy with energy dispersive X-ray analysis of paint cross-sections are used to describe the appearance and elemental composition of affected paint layers. Fourier Transform Infrared Spectroscopy (FTIR) is used to confirm the presence of zinc carboxylates and static secondary ion mass spectrometry (SIMS) results are given for one sample. Scanning electron microscopy energy dispersive X-ray (SEMEDX) maps and spot analyses are used to examine aggregates in detail. In addition to zinc, carbon and oxygen, magnesium is frequently present. Paint composition and environment are discussed in terms of their potential to influence soap formation.

Zinc oxide-centred deterioration in 20th century Vietnamese paintings by Nguyễ Trọng Kiệm (1933–1991)

Abstract Five paintings dated 1963–1980, by Vietnamese artist Nguyễn Trọng Kiệm (1933–1919) in the Witness Collection, are investigated through study of paint cross–sections. Zinc oxide predominates in all paintings, and has strongly influenced their ageing. Widespread flaking is an ongoing concern. Unusual zinc and sulfur containing lumps in one early work have been investigated previously, and the mechanism of formation is reassessed. Paint samples are examined using optical microscopy, scanning electron microscopy with energy dispersive X–ray analysis, X–ray microdiffraction and FTIR techniques. Of key interest are zinc carboxylates, basic zinc carbonate and zinc sulfates as products of deterioration. No evidence is found to support the presence of crystalline zinc sulfate. Layered basic zinc salts incorporating carboxylate, carbonate and sulfate moieties are proposed as an alternative. Hot, humid conditions and pollution levels in Vietnam coupled with paints containing zinc oxide of different grades and the presence of unpigmented medium or size layers are significant factors in the condition of these paintings.

Zinc White and the Influence of Paint Composition for Stability in Oil Based Media

Zinc oxide is a prevalent pigment in twentieth century oil based paints. Its reactivity with fatty acids has consequences for paint film properties and stability. Resulting zinc carboxylates are implicated in a variety of deterioration phenomena affecting late nineteenth and twentieth century paintings. Naturally aged artists’ oil paints and reference paint film draw downs are investigated using scanning electron microscopy, and conventional attenuated total reflectance and synchrotron transmission Fourier transform infrared spectroscopy. This study reports results for soybean oil paints and Naples yellow hue pigment mixtures with zinc oxide in addition to previously reported findings for linseed and safflower oil based paints involving zinc oxide alone and in combination with lead and titanium whites. A solvent model examining interactions between zinc oxide and stearic acid or aluminium stearate supports observations made in paint films. The significance of aluminium stearate as a stearic acid source in paint formulations is corroborated and is more significant than oil type or pigment combination for formation of high concentrations and more pronounced separation of saturated C16 and C18 chain zinc carboxylates.

The Materials and Techniques of William Robinson

The William Robinson Gallery is the only gallery in Australia dedicated to the work of a living artist. The significance of this collection in conjunction with the artists co-operation has provided impetus for a research project dedicated to compiling a technical art history of Robinsons materials and techniques for posterity, and to inform long-term conservation of the artists works. Artists interviews, technical analysis and an online conservation survey reveal that Robinsons materials and techniques evolved in response to the changes in his subject matter and also highlighted discrepancies where the presence of certain materials, or lack thereof, was unintended by the artist. Some of these materials, such as zinc stearate, are associated with deterioration in the artists’ work. Samples from 16 paintings were investigated using a combination of analytical techniques including optical microscopy, ultraviolet fluorescence photography, Fourier Transform Infrared microspectroscopy, Scanning Electron Microscopy with Energy Dispersive X-ray analysis and Synchrotron source Fourier Transform Infrared microspectroscopy.

Ian Fairweather and water-based emulsion house paints in Australia 1950–64

Abstract A study of 13 paintings dating between 1950 and 1964 by artist Ian Fairweather (1891–1974) is used to explore the painting materials available to the artist in the 1950s and early 1960s in Australia. Research explores the key dates of 1939, when Fairweather acknowledged he had an allergy to oil paint (turpentines) and thus discontinued its use, and the date of 1958, when he is first recorded as using water-based synthetic polymer emulsion house paints. Research into release dates of water-based commercial paints through the 1950s and early 1960s is presented, and discussed in relation to preliminary analysis using Fourier Transform Infrared Spectroscopy (FTIR) and Pyrolysis Gas Chromatography Mass Spectroscopy (PyGCMS). In Fairweather’s paintings, oil-modified alkyd binders are found throughout the 1950s, despite the artist’s own assertions that he stopped using solvent-based paint in 1939. Discussion includes the possibility that the oil-modified alkyds found in paintings from the 1950s were oil in water emulsions. Poly vinyl acetate binders have been found on Fairweather’s paintings from 1958 and this aligns with release dates of water-based synthetic polymer paints in Australia.