Stuttgart Muhlhausen, Germany

Stuttgart State Academy of Art and Design
Stuttgart Muhlhausen, Germany
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Echard J.-P.,Laboratoire Of Recherche Et Of Restauration | Echard J.-P.,French National Center for Scientific Research | Bertrand L.,Synchrotron Soleil | Von Bohlen A.,Leibniz Institute for Analytical Sciences | And 9 more authors.
Angewandte Chemie - International Edition | Year: 2010

Figure Presented What is Stradivari's "secret"? The composition of the mythical varnish that coats Stradivari's violins has raised controversial assumptions for the past two centuries. By using a complementary array of analytical tools, the chemical microstratigraphy of these varnishes has been established. The results provide information on the materials and techniques that were used by the Master, with a detailed characterization of the varnish chemical equation presentation © 2010 Wiley-VCH Verlag GmbH &. Co. KGaA, Weinheim.

Bertrand L.,Synchrotron Soleil | Robinet L.,Synchrotron Soleil | Cohen S.X.,Synchrotron Soleil | Sandt C.,Synchrotron Soleil | And 6 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

The study of varnishes from musical instruments presents the difficulty of analysing very thin layers of heterogeneous materials on samples most of which are generally brittle and difficult to prepare. Such study is crucial to the understanding of historical musical instrument varnishing practices since written sources before 1800 are very rare and not precise. Fourier-transform infrared (FTIR) spectroscopy and imaging methods were applied to identify the major chemical components within the build-up of the varnish layers on a cello made by one of the most prominent French violin-makers of the eighteenth century (Jacques Boquay, ca. 1680-1730). Two types of FTIR imaging methods were used: scanning with a synchrotron-based microscope and full-field imaging using a 2D imager with a conventional source. An interpretation of the results obtained from these studies on the Boquay cello is that the maker first applied a proteinaceous layer, probably gelatine-based animal glue. He later applied a second layer based on a mixture of a drying oil and diterpenic resin from Pinaceae sp. From an historical perspective, the results complement previous studies by describing a second technique used for musical instrument finishes at the beginning of the eighteenth century in Europe. © Springer-Verlag 2010.

Pataki-Hundt A.,Stuttgart State Academy of Art and Design | Hummert E.,Freelance Conservator
Restaurator | Year: 2016

Two aspects of consolidation of powdery paint layers are discussed in this paper: First, the colour stability of different consolidation media including cellulose and protein based materials was evaluated. Film sheet samples of the adhesives were exposed to a Xenontester for 276 hours to reach Blue Wool Standard 7. Light exposure caused loss of colour rather than yellowing in most adhesives which correlates to microfading tests. Secondly, colour changes of the pigment layer during application of consolidation media with an aerosol generator were examined. Any shift of colour results in a change of surface structure rather than a detectable shift seen in the ΔE∗ab-values and the reflectance graphs. Thus, the application of aerosols is a very controllable, long-term stable method and results only in minor changes when applied in multiple layers. © 2016 by De Gruyter.

Eggert G.,Stuttgart State Academy of Art and Design
Corrosion Engineering Science and Technology | Year: 2010

Corroding glass forms alkali(ne) surface films, which may lead to special metal corrosion products in the contact zone, for example different sodium copper carbonates or basic sodium lead carbonate. Sodium copper formate acetate was found on objects exposed to long term emissions from wood. A higher pH value may also lead to basic compounds, which normally do not form, e.g. the newly characterised Cu2(OH)3 HCOO. The alkaline films also create a reactive environment for the formation of formates from formaldehyde (e.g. emitted from glues) due to the Cannizzaro reaction or possibly from the neglected pollutant carbon monoxide. Further products containing, for example, potassium or sulphate may be expected. © 2010 Maney Publishing.

Hummert E.,Stuttgart State Academy of Art and Design | Pataki-Hundt A.,Stuttgart State Academy of Art and Design
Restaurator | Year: 2010

Objects damaged by flooding frequently present encrusted layers of mud and discolorations of varying intensity. Standard washing techniques do not permit a removal of the dried mud encrustations, which are mostly of mineral origin. Using an ultrasonic oscillator in the water bath, mud encrustations are unblocked and can be removed. A further improvement of the treatment can be achieved by a local subsequent cleaning using a Blitzfix-Sponge soaked in the non-ionic surfactant, Triton X-100™. The technique was successfully applied for the cleaning of a colour woodcut by Hans Hartung (1904-1989) which was heavily soiled with mud. © 2010 De Gruyter Saur.

Dinnebier R.E.,Max Planck Institute for Solid State Research | Runcevski T.,Max Planck Institute for Solid State Research | Fischer A.,Stuttgart State Academy of Art and Design | Eggert G.,Stuttgart State Academy of Art and Design
Inorganic Chemistry | Year: 2015

In the course of the investigation of glass-induced metal corrosion processes, a microcrystalline sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(H2O)4(OH)2, was detected on a series of antique works of art, and its crystal structure was determined ab initio from high-resolution laboratory X-ray powder diffraction data using the method of charge flipping, simulated annealing, and difference-Fourier analysis (P42/n, a = 8.425«109(97) Å, c = 17.479»62(29) Å, V = 1240.747(35) Å3, Z = 8). In the crystal structure, the metal cations are interconnected in a two-dimensional metal-organic framework via the oxygen atoms of the formate, hydroxide, and oxide anions. Doublets of face-sharing square pyramidal Cu2+ polyhedra are linked via a single, central oxide oxygen atom to give a paddle-wheel arrangement, while the Na+ cations are organized in Na2O11 moieties with highly disordered, edge-sharing octahedral coordination. In addition, hydrogen bonding plays an important role in stabilizing the crystal structure. © 2015 American Chemical Society.

Banik G.,University of Applied Arts Vienna | Bruckle I.,Stuttgart State Academy of Art and Design
Restaurator | Year: 2010

The unique attributes of water are discussed, focusing on its physical interaction forces that operate and between water molecules and other materials to which it can establish a close contact, such as cellulose or paper. Selected scientific principles of the water interactions relevant to water damage focusing on water absorption of cellulose are highlighted, followed by selected drying strategies for cellulosic materials discussed for their mechanisms and side effects. The contribution is an excerpt of the textbook Water in Paper: A Guide for Conservators (Elsevier, Butterworth-Heinemann, in print). © De Gruyter Saur 2010.

Hummert E.,Stuttgart State Academy of Art and Design | Henniges U.,Christian Doppler Laboratory | Potthast A.,Christian Doppler Laboratory
Cellulose | Year: 2013

For the conservation of artworks on paper, powdery paint layers on the paper matrix are stabilized with dilute solutions of adhesives (0.25-1 %), commonly gelatin or methylcellulose, which are applied as aerosols. This technique allows non-contact application. The distribution of the adhesives must be carefully controlled: they have to be delivered to unstable paint layers in the right quantity to avoid visual alterations of the artwork during the stabilization treatment. To visualize the distribution of aerosol-misted adhesives in porous substrates, gelatin and methylcellulose were labeled with fluorescent dyes, purified from excess label, and applied on sample specimen featuring powdery pigment layers on handmade rag paper. As blank comparisons, sample papers without pigment layers were included to verify whether aerosol-misted adhesives are a suitable method to stabilize fragile papers. Penetration of the adhesive-label-conjugates was observed at thin sections of the samples by fluorescence microscopy. The fluorescence labeling of gelatin with Texas Red™ allowed an excellent visualization of aerosol-misted adhesive (0.5-1 %) in all sample types. Methylcellulose (Methocel™ A4C) labeled with Texas Red™ C2-dichlorotriazine enabled fluorescence tracing if applied in 0.5 % solutions by immersion. Aerosol application permitted local adhesive application, making it a suitable technique for stabilizing fragile papers. If applied to samples with low porosity, aerosol-misted gelatin was mainly deposited at the surface, whereas in porous filter paper, penetration dominated over surface deposition. Intermediate drying between repetitive applications apparently limited the penetration of aerosol-misted gelatin. © 2013 Springer Science+Business Media Dordrecht.

Schonemann A.,Stuttgart State Academy of Art and Design | Edwards H.G.M.,University of Bradford
Analytical and Bioanalytical Chemistry | Year: 2011

Tung oil is favoured in applications such as historic wood consolidation or as varnish component that require a rapid-drying medium compared with linseed oil and other analogues such as walnut oil and poppy seed oil. The Raman spectra of tung oil and artificially aged specimens have been obtained and indicate that severe degradation of the C=C unsaturation sites occurs compared with the slower-drying linseed oil. Characteristic spectral signatures of fresh tung oil have been identified which provide diagnostic discrimination between this oil and others used in the preparation and preservation of artworks. Mid-infrared spectra of aged tung oils have served to identify the formation of acidic functionalities which could affect associated pigments and substrates in artwork. Comparative spectra are also reported for a range of other oils such as walnut seed, poppy and sunflower seed oils. © 2011 Springer-Verlag.

Buchta D.,University of Stuttgart | Hein N.,Stuttgart State Academy of Art and Design | Pedrini G.,University of Stuttgart | Krekel C.,Stuttgart State Academy of Art and Design | Osten W.,University of Stuttgart
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Because artworks are a major part of our culture their preservation is of great importance and therefore they need to be protected from any damage. But the change of environmental conditions like temperature or humidity leads to internal stress, which can result in different defects like delaminations or cracks. The deteriorations occurring due to ageing or transport are often small and invisible, but they can enlarge and produce new irreversible damages. Therefore it is important to detect small changes in the surface as well as deteriorations under the surface. A combination of fringe projection and shearography data is a very suitable method to fulfill this task. While fringe projection is used to determine the surface structure, the shearography gives information about the strain occurring due to loading, which allows conclusions about weaknesses in the internal structure. We optimized both techniques for the use in the preservation of artwork and combined the resulting data by a mapping process. In this paper we present the advantages and also the limits, which need to overcome. © 2015 SPIE.

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