Petronella Nel

A preliminary investigation into the identification of adhesives on archaeological pottery

Abstract The successful removal of a failing adhesive from archaeological pottery is facilitated by its identification. The aim of the present study was to establish an analytical path for the identification of adhesives commonly found on archaeological pottery, using resources that would be accessible to a conservation laboratory in Australia. Consultation and research of literature established adhesives that were historically used to repair archaeological pottery. Analysis of control samples assessed a spectrum of analysis techniques (visual, chemical and instrumental). It was found that simple analysis methods such as appearance, UV fluorescence and solvent solubility, are useful for identifying natural products, such as shellac and animal glue; chemical spot tests allow identification of animal glues and cellulose nitrate; and Fourier transform infra-red aids with identifying the presence of additives and with differentiating between poly(vinyl acetate) and acrylic formulations. These observations from the control samples were used to develop an analytical path for identifying adhesives associated with archaeological pottery. This path was tested on adhesive samples obtained from three artefacts in the Cypriot Collection at the University of Melbourne. Five adhesive samples were identified to be based on either cellulose nitrate, poly(vinyl acetate) or an acrylic. These identifications showed the usefulness of the analytical path developed and allowed an assessment to be made of adhesive performance. However, this exercise also raised unexpected questions.

Peacock Ink: Investigation into the Constituents of the Most Prized Ink of Persia

Abstract Peacock ink, known as Murakkabi ṭāvūsī, was created and used by Persian master calligraphers especially from the 14th century onwards. It is a sub-category of Persian ink which contains four main ingredients: lamp black, gum Arabic, green vitriol (ferrous sulphate) and gall nut extract (tannic acid). It is differentiated from other inks in that it contains many additional secondary ingredients which will be covered in this paper. Peacock ink derives its name from the range of different coloured materials added to the ink as well as the blue-green undertone this predominantly black ink is said to have. It is reputed to be a high-quality product, rumoured to stay on paper for centuries and is not affected by water, abrasion or other detrimental factors. It was the aim of this investigation to identify and describe in detail ingredients used to make this ink by finding and translating 17 recipes contained in 11 Persian treatises (15th–16th ce). Of the 31 ingredients found, 16 are plant based, 13 minerals, and 2 animal (protein) based, and in all cases water was used as the vehicle.

Fluorimetric Analysis of the Constituent Dyes Within Daylight Fluorescent Pigments: Implications for Display and Preservation of Daylight Fluorescent Artwork

Abstract Daylight fluorescent pigments are formulated with a select range of colorants that both absorb and emit strongly in the visible region. To ensure best practices in the preservation and authentication of artworks that contain daylight fluorescent colorants, this study investigates the fluorescent dye formulation behind daylight fluorescent pigments by specifically examining the DayGlo daylight fluorescent pigment range. A recently developed extraction–separation protocol was applied to isolate individual dye components of each pigment for fluorescence analysis. Through fluorimetric analysis at the constituent dye level, the formulation behind each pigments observed hue was characterized and interaction by energy transfer between specific dye pairs was established. This research finds that complex dye formulations employed in daylight fluorescent pigment manufacture raise several implications for the display and treatment of this modern palette.

Tea: An Alternative Adsorbent for the Preservation of Cellulose Triacetate Film

Cellulose triacetate (CTA) film, the main film base of the Twentieth Century, is inherently unstable, affected by autocatalytic deterioration through hydrolysis. The release of, and subsequent exposure to, acetic acid known as ‘vinegar syndrome’ accelerates deterioration, placing all cellulose acetate materials at risk or actively deteriorating. Preservation techniques rely on cold storage to slow deterioration or microenvironments with adsorbent materials to remove corrosives and/or pollutants. However, commercially available adsorbents can be expensive and difficult to access. This research investigated the potential for tea and tea waste to act as an alternative, low cost, accessible adsorbent for the preservation of CTA film. Adsorption capabilities of various tea varieties and treatments were compared with activated charcoal, silica gel and molecular sieves. Testing established tea as an effective adsorbent of water and acetic acid vapour, with an aversion to adsorption of the plasticiser dibutyl-phthalate. Use of tea waste also involves additional cost, sustainability and accessibility benefits along with lessened corrosive potential. These findings support tea as a potentially viable alternative adsorbent for the preservation of CTA film, requiring further research into optimum application systems.

Negotiated Outcomes: Investigating Comparative Colour Change of Proprietary Artist Coating Materials for Contemporary Paintings

A new practice is emerging in Australian contemporary art where an epoxy resin is applied as a poured coating onto paintings to obtain a glassy, high-gloss surface layer. However, as the epoxy resin ages it causes undesirable aesthetic and structural issues for the artworks, including yellowing and delamination. As epoxies are known to have limited reversibility, remediation treatment is problematic. In response to artists’ increased usage of epoxy resin coatings as a finish for paintings, various commercial brands have released epoxy-based products, advertised to be resistant to yellowing. In addition, other proprietary brands of artists’ materials have released acrylic emulsion-based products formulated to create a high-gloss surface similar to the epoxy coatings. The primary aim of this research was to evaluate and compare the deterioration characteristics of several proprietary epoxies and an acrylic resin, known to be used as coatings on contemporary paintings, using accelerated ageing and colourimetry analysis. In addition, a contemporary artist who uses these materials was interviewed regarding their practice and expectations of the coating material. This study aims to inform artist selection regarding the performance and stability of the tested proprietary epoxy or acrylic resin coatings for contemporary paintings.

Preliminary testing of tea leaves as alternative adsorbants for preserving early cellulosic motion picture film

Cinematic motion picture film composed of cellulose nitrate or cellulose acetate is an inherently unstable material (Ram, AT 1990, ‘Archival preservation of photographic films—A perspective’, Polymer Degradation and Stability, vol. 29, pp. 3–29; Morgan, J 1991, Conservation of plastics, The Conservation Unit of the Museums & Galleries Commission and the Plastics Historical Society, London). Currently, effective preservation largely relies on cold storage to slow deterioration. Adsorbent materials used in conjunction with cold storage may further extend film lifespan by trapping excess moisture and autocatalytic vapours given off by degrading polymer films. Commercial adsorbants commonly used are: activated charcoal, molecular sieves or silica gel. However, these materials are expensive and can be difficult to access. This research examined the potential of Tea Leaves as an alternative adsorbant for preserving motion picture film. Initial water adsorption testing of three different teas compared to activated charcoal, molecular sieves and silica gel, indicate Tea Leaves are worthy of undergoing further testing for acid vapour adsorption.

Artworks and Cultural Heritage Materials: Using Multivariate Analysis to Answer Conservation Questions

The key concepts of data management systems that are applied to combinatorial and high-throughput chemical systems may also be applied to assist with answering questions involving conservation and cultural heritage materials. The chapter begins with an overview of conservation and explains what conservation is, why it is important, and how it is implemented for the preservation of cultural materials. The inherent value of most cultural materials imposes certain limitations on the types of analytical approaches that may be employed during analysis. An emphasis on noninvasive, nondestructive or microsampling is important to minimize the impact of analytical methodologies upon the artefact that is being studied, and multivariate approaches can maximize the information that may be derived from an analytical technique. In a review of nondestructive analysis and testing of museum objects, Adriaens (Spectrochimica Acta Part B: Atomic Spectroscopy 2005, 60 (12), 1503–1516) reiterates an important conservation principle, i.e. that we should aim for the maximization of information with a minimization of consumed volume of sample. Consistent with other applications in the fields of remote sensing, analysis of metadata and high-throughput or combinatorial approaches, methods for visualization of complex data, multivariate analysis and processing of high volumes of data, advanced data compression using data transformation and cluster analysis for data exploration and mining or pattern recognition are utilized. Cultural heritage studies are often directed at specific compositional and sample relational questions, due to the fact that little documentation about the specific preparation of the artefact exists. Also, because the analyst is dealing with natural materials with inherent sample variability, there is often little a priori knowledge of the sample set, so unsupervised approaches are useful for data exploration. This chapter presents a number of case studies that are used to illustrate the use of multivariate analysis (MVA) and chemometric approaches in studies of cultural artefacts and works of art. By deriving correlations, trends, clusters trajectory and anomalies or outliers in nonspatial and spatial data sets, a number of specific conservation issues are addressed. Firstly, in a multi-year study, the surface mineralogical profile of Australian Aboriginal Rock Art petroglyphs was examined using visible–near infrared reflectance spectroscopy and principal component analysis (PCA). A Cypriot pottery collection repaired with adhesives was studied using Fourier transform infrared (FTIR) spectroscopy and further historical information was revealed using PCA. The pigments and binding media used to decorate an Egyptian sarcophagus were examined with Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and X-ray absorption near-edge structure spectroscopy (XANES), and attribution studies of an Italian renaissance painting and imaging of ochre pigments using X-ray fluorescence (XRF) elemental imaging are presented.

Context, access and communication strategies: complementary pathways to the conservation of a once-forgotten chemistry collection

Abstract In 2007 the School of Chemistry Collection returned to the University of Melbourne, after a 27-year loan to Museum Victoria. At that point its significance was unclear. However, with the application of the significance assessment methodology, awareness was soon raised about the worth of the collection. Next, a modest display was used to increase the profile of the collection, resulting in funding for ongoing conservation activities. Circumstances required the conservator to act more broadly, in a combined role of conservator, curator and subject specialist. In working outside a narrowly defined role, several unexpected positive outcomes were achieved, leading to renewed interests in the research, use and conservation of previously undervalued heritage material. These events and the unique story of this particular Collection are set within the historical context of museum collections in general. The paper argues for conservators to play a proactive role in advocating for collections, by highlighting various benefits, which resulted from holistic conservation involvement in this project.

Identification of a white substance on 20th century leather bindings

Abstract The aim of this investigation was to identify a white substance visible on the spines of leather-bound volumes titled Victorian Law Reports and address any issues of concern. Initially it was thought that it was a mould outbreak. However, preliminary examination using visual and microscopic methods ruled this out. An analytical path which involved Environmental Scanning Electron Microscopy with Energy Dispersive Spectroscopy (ESEM-EDS), micro-chemical spot testing and Fourier Transform Infra-red (FTIR) spectroscopy determined that the white substance was composed of one or more fatty acids and possibly their respective calcium salts. In addition, this investigation provides a review of the available literature and an analytical path for identifying white bloom on leather bound volumes.