Baeten J.,Catholic University of Leuven |
Romanus K.,Catholic University of Leuven |
Degryse P.,Catholic University of Leuven |
De Clercq W.,Ghent University |
And 7 more authors.
Microchemical Journal | Year: 2010
During archaeological excavations of the Castle of Middelburg (Belgium), a 16th century ceramic vessel containing a greasy substance was found. A wide range of chemical techniques was applied on what was presumed to be an ointment to reveal its nature and function. The organic fraction, constituting about 24 wt.%, was analyzed by chromatography and mass spectrometry and consists of beeswax next to smaller amounts of a triglyceride lipid source. Infrared analyses indicated the presence of calcium carboxylate soaps. The inorganic ingredients represent about 30% of the total mass. While calcium, lead and iron were detected by elemental analysis, X-ray diffraction revealed calcium sulfate (gypsum) and lead sulfate as major minerals. Detailed study by X-ray photoelectron spectroscopy confirmed the presence of lead as a divalent species. Altogether, these results point to a medicinal formulation of a lead plaster, used for treating bruises, mixed with beeswax, which was added for easy application on the skin. It is further assumed that lead carboxylates, originally present in the sample, reacted with gypsum, resulting in the formation of calcium carboxylates and lead sulfate. Gypsum could have been added to whiten or to strengthen the plaster. Hence, the analyses confirm the presumed medicinal nature of the find and add it to the list of very rare finds of preserved historical ointments. © 2009 Elsevier B.V. All rights reserved.
Hagan E.W.S.,Canadian Conservation Institute |
Charalambides M.N.,Imperial College London |
Young C.R.T.,Somerset House |
Learner T.J.S.,The Getty Conservation Institute
Applied Physics A: Materials Science and Processing | Year: 2015
Acrylic artist paints are viscoelastic composites containing a high molecular weight copolymer, pigment and a variety of additives.The glass transition temperature of the latex binder is typically slightly below ambient conditions, giving mechanical properties that are strongly dependent on strain rate and temperature. In previous work, the viscoelastic behaviour of custom-formulated latex artist paints was reported for films with known volume fractions of pigment using data from uniaxial tensile tests at different strain rates and temperatures.Secant Young’s modulus and failure strain master curves were constructed for each film through time-temperature superposition, allowing predictions beyond the experimental timescale at a selected reference temperature.A similar analysis is now presented for a small set of commercial artist paints tested at ages of 1 and 27 years. Experimental shift factor values are reported with fits to the Arrhenius, WLF and Vogel Fulcher equations, along with a comparison with published data for acrylic polymers. The tensile results highlight a spectrum of properties that acrylic paints may exhibit—brittle glass to hyperelastic—depending on the conditions during deformation. Strong similarities are shown between products from different manufacturers, and the findings suggest a high degree of stability with age. A method for predicting failure as a function of strain rate and temperature is also presented, and the methodology gives a framework for investigating other artist materials and the factors influencing their mechanical properties. © 2015 Her Majesty the Queen in Right of Canada as represented by Canadian Conservation Institute
Canamares M.V.,City College of New York |
Leona M.,The Metropolitan Museum of Art |
Bouchard M.,The Getty Conservation Institute |
Grzywacz C.M.,The Getty Conservation Institute |
And 2 more authors.
Journal of Raman Spectroscopy | Year: 2010
The identification of organic colorants in works of art (such as dyes on textiles or organic pigments) by Raman spectroscopy is generally limited by the presence of a strong fluorescence background. In this paper, the effectiveness of minimizing fluorescence in the analysis of Cape Jasmine (Gardenia augusta L.) by dispersive Raman spectroscopy at three different excitation wavelengths (633, 785 and 1064 nm) and by surface-enhanced Raman spectroscopy (SERS) with and without acid hydrolysis is evaluated and compared. It is shown that these vibrational techniques offer an alternative analytical approach, when, as is particularly the case of Cape Jasmine, sample preparation procedures that are routinely applied for natural organic dyes andpigments cause alterations that leadto low sensitivityin the more classical high-performance liquid chromatography-photodiodearray (HPLC-PDA) analytical protocols. Samples of the yellow dyeG. augustaL. In the following forms were analyzed: dyed on alum mordantedwool, dyed on nonmordanted and alum mordanted silk, pigment precipitated on hydrated aluminum oxide, extract mixed with a protein binder and painted on glass, and as a water-based glaze applied on a mock-up of a typical Chinese wall-painting. Raman bands at 1537, 1209 and 1165 cm-1 are identified as discriminating markers for the carotenoid colorant components crocetin and crocin. © 2009 John Wiley & Sons, Ltd.
Cancino C.,The Getty Conservation Institute |
Torrealva D.,Catholic University of Peru
Seismic Retrofitting: Learning from Vernacular Architecture - Vernacular Seismic Culture in Portugal Research Project Funded under the National Research Agency FCT, SEISMIC-V 2013 | Year: 2015
During the 1990s, the Getty Conservation Institute (GCI) carried out a major research and laboratory testing program - the Getty Seismic Adobe Project (GSAP) - to investigate the seismic performance and develop effective retrofit methods for historical adobe structures. In April 2006, the GCI’s Earthen Architecture Initiative (EAI) hosted an international colloquium, in order to assess the impact and efficacy of the GSAP. The participants concluded that the GSAP methodology was reliable and effective, but its reliance on high-tech materials and professional expertise was a deterrent to its wider implementation. In response to these conclusions, the EAI initiated, in 2010, the Seismic Retrofitting Project (SRP) with the objective of adapting the GSAP guidelines, so that they better matched the equipment, materials, and technical skills available in many countries with earthen buildings. Peru was selected as the project’s location, due to its current and historical knowledge and professional interest in the conservation of earthen sites. © 2015 Taylor & Francis Group, London.