An Evaluation of Glazing Materials and their Effects on Fading in Fluorescent Acrylic Paints
Fluorescent paints have been used in artwork from the mid-twentieth century onwards, being particularly prominent in the pop art movement. In addition to their bright colours and luminosity, these are also known to be fugitive. Conservators may use glazing materials to protect the artwork so as to avoid applying anything directly to the acrylic paint surface. Museum environments usually exclude ultraviolet light, so the artworks are subjected to the visible part of the electromagnetic spectrum. Besides protection from ultraviolet light, can glazing offer protection from light damage in the visible spectrum? The goal of this research was to evaluate fluorescent acrylic paints from the Tri-Art Company as well as three different glazing options currently used in museums (Sheffield Bayer Makrolon®, Plexiglas® MC, TruVue® Optium Museum). The aim was to determine how the paints maintain their colour and vibrancy with overlaying glazing. Samples were subjected to three types of aging: natural light aging, extreme light exposure in a Q-Sun Xenon Arc test chamber at two time intervals, and micro-fading. To determine the efficacy of the glazing, the following tests were conducted: pyrolysis gas chromatography mass spectrometry (Py/GC-MS), Fourier transform infrared (FTIR) spectroscopy, colorimetry measurements, and ultraviolet-visible solid-state absorption spectrometry. The results indicate a quicker propensity for fading to occur in samples with glazing than in samples without. This was true wherever ultraviolet was excluded. The increase in fading rates was unexpected, but demonstrates a necessity for a closer look at the effects of glazing in museum environments.
Candied Cedar Bark: The Treatment of Waterlogged Western Red Cedar Bark Using Sucrose
Western red cedar bark has been used for centuries by the First Nations peoples of the Northwest Coast; however the objects made from this material rarely survive in archaeological sites except for those objects found in waterlogged conditions. The survival of these materials is dependent upon their conservation treatment following excavation. Traditionally waterlogged archaeological cedar bark has been treated with polyethylene glycol 400 (PEG 400), but this treatment has received mixed reviews and does not always produce a predictable result. Sucrose was used successfully as an impregnant for waterlogged wood for many years, but so far it has not been used on bark. The purpose of this investigation was to determine whether waterlogged western red cedar bark can be successfully treated using sucrose. This research employed modern waterlogged samples of western red cedar bark prepared at the Canadian Conservation Institute (CCI), which had been soaking in water for fourteen years. Some of this sample material had been further degraded to mimic the deterioration present in archaeological waterlogged cedar bark. A third set of samples came from a supply of archaeological waterlogged western red cedar bark recovered from the Lachane site in the harbour at Prince Rupert, British Columbia. The samples were cut to a uniform size and each was soaked in solutions of increasing concentration of sucrose to a maximum concentration of 70% w/v sugar in water. Soaking times varied from two to six months. The samples were air dried, the most common method of drying associated with sucrose impregnation. A group of control samples that remained untreated was air dried at the same time as the treated samples. A second set of control samples was treated with PEG 400 as this is the standard method used to treat waterlogged cedar bark at CCI. To determine the degree of penetration of the sucrose, the samples were examined using scanning electron microscopy and by analysing the concentration of sugar deposited in the samples using extraction and refractometry. The effectiveness of the treatment was also assessed as regards the stability of the samples, final appearance, and handling properties. The sucrose treated samples demonstrated good dimensional stability, although they were not flexible, they were not brittle, which is encouraging. The samples treated with sucrose did darken significantly following treatment, however, which may be a deterrent from using this method.
The Use of Electrolysis in Removing Soluble Salts from Paper
The aim of this research was to determine whether electrolysis could be used to remove soluble salts from paper damaged by seawater more effectively than regular washing. Two different types of watercolour art paper were used in the trials, one uncalendered, rough finish paper and a hot-pressed smooth finish paper, to determine whether the surface finish and porosity of the paper would have on effect on the absorption and desorption of salts. A simulated salt water solution was prepared to a salinity of 35.5 parts per thousand, to mimic the natural salinity of seawater. The samples were placed in a climate control chamber for eight weeks at a temperature of 80°C and a relative humidity of 65%. Three control groups and two experimental groups were used. Samples were submerged in the salt water solution for either 12 hours or 24 hours, and then treated with either low-current electrolysis (30 volts) or washing in demineralized water for 90 minutes. Control groups were used to determine the effect of washing and electrolysis on paper that had not been exposed to salt water. Inductively coupled argon plasma emission spectra was used to determine the level of residual sodium in after treatment. Samples were tested for standard tensile elongation strength and fold endurance. Results showed that electrolysis did remove the salt water from paper more effectively than regular washing. All washed papers were found to be much stronger than any untreated papers, although the cause for this is yet unknown, it may be due to the rearrangement of the paper fibres caused by wetting.
Calcium Phytate: A Treatment for Degraded Tacking Margins
Jennifer A. Morton
Paintings constructed of linen canvas affixed to their stretcher by uncoated iron tacks are susceptible to degradation. As the tacks age and corrode, the oxidation products including iron (II and III) ions can migrate into the surrounding canvas of the tacking margin. The presence of iron (II) ions can cause the linen threads of the canvas to become brittle and acidic. This is similar to the situation encountered in paper conservation with documents containing iron gallotannate or iron gall ink. In order to simulate these conditions, linen threads were artificially rusted using a two-step aqueous chemical process involving iron (II) sulphate and ammonium hydroxide. To accelerate the aging process, threads were stored in an environment test chamber for several weeks at elevated temperatures (80˚C - 100˚C) and increased relative humidity (65%). Threads that had been either rusted or not, or aged or not were then treated using the paper conservation process which employs calcium phytate in conjunction with calcium bicarbonate to complex the active iron (II) ions and decrease the acidity of the surrounding material support. Randomly selected threads from the various treatment combinations were assessed for the presence of iron (II) ions (bathophenanthroline test strips), their acidity (pH), their tensile strength (Tensometer) and their flexibility (Mandrel test). This study established that both the artificial rust treatment and the accelerated aging process provided an excellent simulation of linen canvas aging as evidenced by the reduction in the tensile strength of the threads. In addition, the calcium phytate and calcium bicarbonate treatment did reduce the concentration of iron (II) ions, but did not impart any increase in the threads’ tensile strength though there was some evidence of improved flexibility.
Finding a New Standard for Rolled Cotton in North American Paintings Conservation
When Johnson & Johnson discontinued the production of the 6026 Red Cross Cotton Roll in 2004, many in the paintings conservation community were at a loss. This cotton product was a preferred cotton for surface cleaning and varnish removal, famous for its sterile quality, long fibers and handling properties. Since Johnson & Johnson’s change in cotton manufacturing, paintings conservators have been searching for a suitable replacement. This research compared those characteristics that made Johnson & Johnson’s 6026 Red Cross Cotton useful in conservation. A small amount of remaining cotton was compared against selected cottons to determine their effectiveness in painting conservation. The cottons were chosen from art conservation suppliers and a local drug store brand. Also tested was a sample of cotton from Robinson Healthcare of Chesterfield in the United Kingdom that had similar properties to the Johnson & Johnson cotton. All have undergone either sterile or non-sterile cotton processes.
Several quantitative and qualitative tests were performed on each sample. Tests included fiber identification, fiber characteristics, metallic contamination testing, absorbency, and usability testing. Fiber identification was carried out using normal and polarized light microscopy and Fourier transform infrared (FTIR) spectroscopy. Fiber characteristics examined included: texture, tear ability, trash and nep content (debris and entangled fibers), color through colorimetery readings using the CIE L*a*b* System (focusing on the L* and b* measurements), and length and length uniformity. Metallic contamination testing was performed using inductively coupled plasma optical emission instrument (ICP-OES) to search for the presence of 30 metals (detects trace amounts in parts per billion). Absorbency testing was preformed using seven swabs from each sample. Each swab was tested for the ability to absorb distilled water. Swabs were weighed using an analytical balance before absorption, rolled onto a bamboo stick, dipped in distilled water, then rolled five times to remove excess water and weighed after absorption using an analytical balance. Residual water left on the balance after the wet swab was removed was also weighed. Usability testing involved testing each sample ten times which included five tests on two different canvases (one textured and one smooth) to determine varnish removal capabilities and assess the number of cotton fibers left behind on the painting’s surface. Test canvases were pre-primed commercial canvases painted with Golden carbon black acrylic paint and spray varnished with Liquitex Soluvar® Gloss Varnish in mineral spirits (30%). Varnish removal was performed with pre-weighed swabs and mineral spirits. Each of the ten tests was limited to a canvas area of 1.5 inches2
A Comparative Study of the Direct Application versus Solvent Reactivation of Klucel G
Since it was first introduced to the conservation field, hydroxypropyl cellulose (HPC) has been of interest to conservators and conservation scientists alike. Today, the most used HPC is Klucel G, most often employed through direct application, but it is also used through solvent reactivation. The goal of this research project is to quantitatively determine the differences between these two application techniques using Klucel G. The strength of the adhesion was tested using an Instron tensile test machine for the lap joint shear strength test and the T-peel test. The flexibility of the adhesion was tested using a Taber-type tester to determine if one method of application formed a more flexible bond than the other. Finally, the diffusion of the adhesive into the substrate was observed using reflected light microscopy to speculate on the reversibility of the treatment and understand the way the adhesion works. This research determines that direct application is stronger than solvent reactivation due to a greater diffusion of the adhesive.
Commercial vs. Formulated: An Investigation of Artificially Produced Patinas Used on Copper in the Field of Jewellery Making
Formulated artificial patinas and non-formulated commercially produced patinas for use on copper are available to contemporary jewelers in North America. Although many patination recipes as well as already artificially produced ones are available, little is known about these patinas in terms of composition, structure and aging. This study deals with artificial black, green and brown patinas that are applied on pure copper plates by using the cold patination technique. Two sets of samples were obtained. The first set used three artificial patinas based on formulated recipes. The other set consisted of other copper plates patinated with three patinas based on empirical recipes that are available as commercial products in stores. Following the treatment, the patinated plates were subjected to high temperature and relative humidity (RH) to analyze the properties of the patina layers and compare the results. Color, adhesion strength, surface morphology and composition of the patinas were investigated before and after the exposure to the extreme environmental conditions. The artificial patinas were evaluated using colorimetry testing, scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), and the ASTM Standard Test Method for Measuring Adhesion Tape Test (D3359-09ε2). The results showed that despite their encouraging qualities, the commercial patinas were more susceptible to color fading and to loose their adhesion strength over time in comparison with formulated patinas. Observing the morphology of the patina layers revealed that the degree of change in the structure of both commercial and formulated patinas depends on the composition of each patina. A better understanding of artificial patinas will assist modern jewelers to make the most suitable choice when using patinas on their work. Also it will allow appropriate methods of conservation to be developed for future treatment of patinnated jewellery artifacts.
Testing the Bond: A Study of Stickers on Contemporary Artwork
Jeanne Beaudry Tardif
Stickers often form part of contemporary artwork. They are found in various collections such as those in the National Gallery of Canada. In contemporary art, a conservator must try to predict the future state of the collection in order to preserve its integrity. Research must be carried out to determine the long-term effects of stickers on their supports. If the stickers contribute to the deterioration of the artwork, then the appropriate preventive treatment must be determined. Deterioration, such as yellowing and brittleness, could affect both the support and the sticker itself. This research focused on detecting any possible deterioration with the stickers and their supports. Initially, numerous commercial stickers were analyzed with Fourier transform infrared (FTIR) spectroscopy to determine their composition. Then, replicas of these works of art were made using self-adhering labels, gelatin silver photographs, and Canson and Strathmore papers. The gelatin silver photographs were developed in a dark room using a standard image. The standard was a grey scale showing different shades of black, white and grey. Numerous tests were performed on replicas before and after aging to determine pH, degree of yellowing and peel strength. The samples were exposed for a period of 28 days to an environment of 65% relative humidity and 80°C. After aging, the samples were generally in good condition. Most of them did not show any noticeable change in chemical properties, pH or color. The aged samples resulted in a stronger bond between the adhesive and the substrate. The aged silver gelatin samples showed a change in color and failed the Photographic Activity Test (PAT).
A Technical Investigation of ‘Devil’s Ledge’ Rock Art: Documentation and Prospects for Conservation
The rock art site known as ‘Devil’s Ledge,’ located on Obabika Lake in northern Ontario, was investigated to determine the state and cause of pictograph deterioration. The site examination included photo-documentation and an analysis of surrounding lake-water, rock stratigraphy, bio-colonization, and mineral deposition on the rock face. With this information in mind, rock samples and red ochre pigment, emulating the conditions at this site, were prepared for testing with two commercial water repellent coatings: SILRES® BS 290 sealer and CeNano Portol Pro nano-silica coating. During sample testing in the laboratory, scanning electron microscopy (SEM) was used to observe the surface texture and structural details of the applied coatings under high magnification. Water contact angles were documented for uncoated and coated rock samples. Concurrently, colour and gloss measurements were taken, before and after ultraviolet light exposure of coated rock and pigment samples. In general, both coatings showed little to no change in appearance of the rock substrate and ochre pigment upon curing and after 250 hours of UV exposure. SILRES® BS 290 sealer was found to have the greatest water repellency and both coatings markedly increased the surface hydrophobicity of the rock substrate. This study was able to assess the initial viability of using the above-mentioned commercial products on exposed Canadian Shield rock and red ochre pigment, in terms of visual and material compatibility. Furthermore, the standard silane-based water repellent (SILRES® BS 290), tested alongside a lesser-known nano-coating (CeNano Portol Pro), served as a benchmark for a comparative study in water repellency.
Evaluating the Efficacy of Silica Nano-Particle “Liquid Glass” Protective Coatings for Outdoor Marble Sculpture and Monuments
Anna Marie Weiss
“Liquid glass” products have been proposed for use as inert and versatile coatings that may have applications in the cultural heritage protection field. These coatings are advertised to consist of silica nano-particles and are held without adhesives or binders to various substrates including metals, textiles, stone, plastics, wood, and glass. By creating a nanoscopic surface texture, these coatings emulate the “lotus effect,” demonstrating a variety of characteristics including hydrophobicity, oleophobicity, water vapour permeability, anti-microbial properties, and “easy to clean” qualities. As these coatings potentially offer protection against several forms of deterioration, they may aid in the preservation of stone architecture, sculpture, and monuments. Conservators and conservation scientists have not yet extensively tested these coatings, and thus further research may determine their suitability and ascertain possible applications in the conservation field. Research conducted at Queen’s University investigated three coatings: Portol Pro from Cenano GmbH & Co. KG and both a Stone Finish and a two part Anti-Graffiti Coating from Nanopool GmbH. Tests determined the efficacy of the coatings as water repellent and anti-graffiti materials. The substrate tested on was the Olympia White marble used to construct the Canadian Navy Memorial Monument in Ottawa. The coatings were characterized by X-ray diffraction, inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy with a DRIFTS attachment, and gas chromatography mass spectroscopy. Environmental scanning electron microscopy investigated the surface morphology of the product on marble and color change was monitored after application and after exposure to high humidity and temperature. Water repellency was measured with RILEM tubes and water contact angle measurements. Water vapour transmission rates were also compared. Empirical tests were performed to evaluate ease of cleaning following the application of test graffiti, as well as an investigation into the removability of this coating.