J.CAC VOLUME 42 (2017)

Practical Electrochemistry for Conservators and Conservation Scientists: Part I – The Basics of Potential Measurement

Lyndsie Selwyn, W. Ross McKinnon

Electrochemical techniques are used in conservation to identify metals or corrosion products, or to monitor or treat metal objects. Although there are many published reports on these techniques, it is difficult to find practical information on how to get started to use them. This paper provides some of this information for one important application of these techniques, namely measurement of corrosion potential (the potential of an object immersed in a liquid electrolyte with respect to a reference electrode). Topics covered include electrochemical cells, multimeters, electrical connection to objects, electrolytes and, especially, reference electrodes – common types of reference electrodes, how to use, protect and maintain them, and how to troubleshoot problems. Examples are given of measuring corrosion potential and using Pourbaix diagrams.

Download: JCAC42 Selwyn & McKinnon I

J.CAC VOLUME 42 (2017)

Practical Electrochemistry for Conservators and Conservation Scientists: Part II – Characterizing and Treating Corroded Metals

Lyndsie Selwyn, W. Ross McKinnon

Electrochemical techniques can be used to characterize corrosion on a metal object and to reduce the corrosion either to a different compound or back to the metallic state. These techniques involve the flow of electrical current, and so are more involved than the measurement of the potential between an object and a reference electrode in a two-electrode cell. Information is given here for techniques where current flows, including the choice of a third electrode (the counter electrode) and the additional equipment needed (a power supply or potentiostat). Examples are given of methods varying the potential (potentiodynamic), holding the potential constant (potentiostatic), or holding the current constant (galvanostatic). The following aspects are discussed: identifying the features associated with oxygen reduction, associating the peaks in potentiodynamic scans with specific compounds in the corrosion, choosing the potential for treating an object, and estimating the amount of corrosion on an object or a test sample.

Download: JCAC42 Selwyn & McKinnon II

J.CAC VOLUME 42 (2017)

The Treatment of a Catharine Parr Traill Botanical Album

Christine McNair

A treatment was undertaken at the Canadian Conservation Institute to conserve a botanical album compiled by Catharine Parr Traill from the collection of the Peterborough Museum and Archives. The botanical specimens, many detached, were vulnerable to mechanical damage due to the stiffness of the binding. After consultation with conservators at the Canadian Museum of Nature, a treatment method was developed to reattach the detached specimens using micro solvent-set straps of Japanese paper. This solvent-set strapping interfered minimally with the movement of the book’s pages and was comparable to methods used within herbariums. The strips are easily reversible and require minimum moisture and adhesive. Some portions of the specimens were lightly adhered using methyl cellulose. The binding itself was structurally altered by adding a moulded spine hollow in order to improve the opening of the volume and to prevent further mechanical damage.

Download: JCAC42 McNair

J.CAC VOLUME 41 (2016)

Characterization of Artificial Stone Used for Outdoor Monuments and Sculptures in Quebec

Dominique Duguay, Jane Sirois, Melanie Raby, Isabelle Paradis

Artificial stone is often employed in sculptural work and architectural details in Quebec, including many monuments that have fallen into disrepair. During this collaborative project between the Canadian Conservation Institute and the Centre de conservation du Québec, 16 samples were taken from 12 sculptures across Quebec and were analyzed by means of stereomicroscopy, scanning electron microscopy/energy dispersive X-ray spectrometry, thin-section petrography and X-ray diffraction. Some aspects of the analysis, for instance the confirmation of the presence of clinker, proved to be challenging due to the restrictions on sample size required in conservation work. The results indicate that more than half of the sculptures analyzed were hydraulic cement-based artificial stone. The remaining sculptures were made of Coade stone, or lime-, gypsum- or dolomite-containing materials. This research provides a limited survey of artificial stones in Quebec and will help guide conservators in selecting proper treatments for these works by allowing identification and better understanding of the materials.

Download: JCAC41 Duguay et al

J.CAC VOLUME 41 (2016)

Shredded Cedar Bark: A Survey of Past Treatments

Sonia Kata, Carole Dignard

A survey of past treatments for shredded cedar bark was carried out on sixteen objects: two masks from the U’mista Cultural Centre and fourteen similar objects at the Canadian Museum of History (CMH), which had been assessed or treated by the CMH or the Canadian Conservation Institute (CCI) nearly 30 years ago. The objects were examined and evaluated with regard to cedar bark condition, appearance, pH and iron content. Treatments fell into four groups: 1) adhesive consolidation; 2) localized paper supports with adhesives; 3) localized thread wrappings, with or without adhesives; and 4) no treatment, sometimes coupled with a support. Parylene (poly-para-xylylenes) coating was also investigated as CCI carried out tests on cedar bark samples several years ago. Each treatment strategy had some benefits and drawbacks. Iron content was identified as an important factor in condition. A literature review on shredded cedar bark was also conducted to elucidate its properties, processing and conservation.

Download: JCAC41 Kata & Dignard

J.CAC VOLUME 41 (2016)

Technical Note: Magnetic Mounts for Textile and Leather Objects in a Travelling Exhibit

Amanda Harding

This note describes a method to construct mounts for three objects in a travelling exhibit using rare earth magnets. The objects were made of textile and leather and included an original beaded fire bag, reproduction leather mittens and reproduction leg garters. The mounts for the mittens and leg garters were successful but the mount for the fire bag failed in one context.

Download: JCAC41 Harding

J.CAC VOLUME 40 (2015)

Characterization of Varnishes on Nineteenth-Century Canadian Furniture

Elizabeth Moffatt, Amanda Salmon, Jennifer Poulin, Alastair Fox, James Hay

A project was undertaken at the Canadian Conservation Institute to identify the original varnishes on a selection of wooden furniture made in Canada in order to test assumptions about which varnishes were commonly applied to such objects and to gain a better understanding of the varnishing practices of Canadian cabinetmakers. The project focused on pieces fabricated in Ontario and New Brunswick, primarily during the nineteenth century. Varnish samples taken from twenty-one pieces of furniture were analyzed in order to determine their compositions. Objects were chosen based on evidence of the presence of an original varnish and for their strong provenance. Analysis of the varnishes was undertaken by Fourier transform infrared spectroscopy and pyrolysis–gas chromatography–mass spectrometry. Analytical results suggest that the use of fixed oil varnishes incorporating Pinaceae resin and often imported copal resins was more common than the use of shellac, and that it persisted in Canada to at least the end of the nineteenth century.

Download: JCAC40 Moffatt et al

J.CAC VOLUME 40 (2015)

Early Twentieth-Century Artists’ Paints in Toronto: Archival and Material Evidence

Kate Helwig, Elizabeth Moffatt, Marie-Claude Corbeil, Dominique Duguay

Information about artists’ paints available in Toronto during the first decades of the twentieth century was acquired through the examination of archival material and the analysis of historic paints from the paint box of Kathleen Munn and from a Winsor & Newton specimen tint book. The archival and material evidence revealed that the lead sulfate-zinc white paint commonly used by Tom Thomson and members of the Group of Seven was New Flake White from the Cambridge Colours paint brand. The research also highlighted the prevalence of hydromagnesite (magnesium carbonate hydroxide) in Winsor & Newton paints. This filler, which has been identified in paint from early twentieth-century works by several Canadian painters, is characteristic of Winsor & Newton and is not present in the Cambridge Colours. The information obtained gives useful context to previous research on Tom Thomson’s painting materials, and will also inform future scientific studies of painters active in Toronto during this period, including Group of Seven artists.

Download: JCAC40 Helwig et al

J.CAC VOLUME 40 (2015)

Slugs as Potential Pests of Paper

Viktoria Korytnianska

An instance of damage to paper by slugs is presented in this report. Slugs were found in the basement of the National Research Restoration Centre of Ukraine in Odessa. The room appeared to have optimal indoor conditions; however, upon further examination it was found that slugs were inhabiting a microclimate zone, where a large amount of condensation was observed on the cold water pipes. The slugs had damaged newspapers, softcover books, and paper envelopes containing photos. It appears that they ate paper with food, oils and other contamination in the absence of their usual food sources. The slug damage resulted in holes and other losses in the paper as well as contamination by mucus tracks and excrement. Given this, we can conclude that slugs are potential pests of works of art on paper that are stored in damp basements and ground floors.

Download: JCAC40 Korytnianska