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- Damage mechanism (2)
- Deterioration (2)
- Emission (2)
- Gold mosaics (2)
- Quecksilber (2)
- Zinn-Amalgamspiegel (2)
- Adhesives (1)
- Aerosols (1)
- Anti-corrosion systems (1)
- Anti-korrosions Beschichtungssysteme (1)
In this study, bulked adhesives were examined regarding changes in properties for their use in the restoration of stained-glass windows. Two epoxy adhesives commonly used in the restoration of flat glass, Araldite® 2020 and Hxtal NYL-1™, were investigated. The adhesives were mixed with various silica-based micro- and nano-particles as fillers. Different tests were carried out on the adhesives with and without fillers in order to characterise their chemical and mechanical properties. The tests included colorimetry, dynamic-mechanical methods of analysis and tests on bending strength. No property changes could be ascertained in the bulked adhesives that would be negative for the restoration of delicate flat glass.
Several restoration projects of stained-glass windows have been performed in Lower Silesia (Poland) since 2010. The aim of the projects was to protect stained-glass windows against environmental impact of industial pollutants and acid rain by installing a protective glazing. The usefulness of protective glazing has been proved by climate measurements and determination of environmental impact before and after installation.
A number of environmental monitoring projects were performed on historic stained-glass Windows in Germany from 1994 to 2012. The quality of the protective glazing was assessed by recording environmental Parameters in the interspace between the original and the protective glazing and on the inside of the original window. Tor this purpose, temperature, humidity and air velocity were measured. Particles were sampled with different methods and analysed by scanning electron microscopy combined with energy dispersive X-ray spectroscopy to determine their chemical composition. The effect of particles on model glass samples was investigated in climate chambers under accelerated weathering conditions. The results from in situ measurements and laboratory tests were combined to evaluate the potential effect of particulate matter on historic stained-glass Windows.
A comparative study tested the performance of modern anti-corrosion Systems against that of traditional red lead Systems.
One aim of the research project was to find alternatives for the use of a red lead priming coat, the Standard anti-corrosive primer for iron and Steel in the past but a material which endangers health as well as environment. The investigation aimed to determine whether anti-corrosion Systems developed for industrial use were suitable for the Conservation of historic iron and cast iron objects.
Besides coatings containing red lead, several surface tolerant coatings with different anti-corrosion pigments were examined.
The modern anti-corrosion Systems examined were suitable for surfaces where Optimum surface preparation is not practical.
They were applied to both historical samples and to newly prepared model samples.
After uniform pre-corrosion, the model samples were coated and underwent two different ageing procedures: accelerated ageing in a climate chamber and outdoor weathering on a test site with moderate city climate. The specimens were exposed for more than two and a half years. Evaluation of the artificially aged samples was carried out under the aspect coating degradation, tensile strength test, cross-hatch test and Fourier-transform infrared microscope.
The results of the research with optical evaluation and test procedures will be presented. The two ageing methods will be discussed, with different results from the naturally and artificially aged samples. The results Show a similar eligibility of modern anti-corrosion Systems as compared with red lead Systems for the use in Conservation.
ESEM-EDX analyses for the characterisation and reproduction of nineteenth-century gold tesserae
(2012)
Environmental scanning electron microscopy with energy dispersive X-ray analysis (ESEM-EDX) is a versatile working tool for the examination of gold tesserae as well as for the selection of suitable materials for their reproduction. In this paper, the ESEM-EDX analyses of original gold tesserae and their damage types are presented. These analytical results form the basis for further calculations of glass properties and experiments. These calculated values enable the determination of the relevant glass properties and allow us to choose the appropriate type of modern glass for further experiments. Subsequent experiments convert this knowledge into practice. By comparing the analytical results from the original glasses and the replicas the accuracy and precision will be shown.
With the implementation of glass casting in France in the second half of the 17th century, larger mirrors could be produced. So-called tin-mercury mirrors were made by coating glass with tin amalgam. Today, many historical mirrors are partly damaged, the image quality is compromised, and the material integrity of the mirror is threatened. The transformation from tin into an oxide starts at the surface of the amalgam and proceeds down to the glass surface. The mercury dissolves as a liquid or gaseous phase. The amalgam layer is destroyed, so that conservation is necessary. Conservators must follow strict safety precautions while handling amalgam mirrors because of possible mercury emissions and corrosion of the amalgam, during which elemental mercury accumulates near the mirror frame in droplets and is emitted into the air.
In a research project, the quantity of the mercury emissions from historical mirrors was examined and a technique to decrease these emissions was developed.
To improve the adhesives used for restoring stained glass windows, various adhesives were tested and modified. Stained glass windows often show gaps that are too wide to be glued with conventional adhesives, and complementing the gap with spare glass is very time-consuming.
To solve this problem, a filler with improved adhesive strength was developed to bridge wider gaps and cracks. The new filler combines glass adhesives with specially treated glass powder.
Three different glass adhesives were selected and mixed with the specially treated glass powder. The adhesive – glass powder mixture developed was then subjected to accelerated aging and analysed with Fourier transform infrared analysis, scanning electron microscopy, colourimetry, and bending and tensile tests. The results were excellent and the mixture was subsequently used to restore glass windows from four 19th-century churches and chapels. The restoration process was described in conjunction with the advantages of using this approach.
This new adhesive – glass powder mixture provides an adhesive process that can be adapted to the special needs of any object being restored and thus provides a ready answer to the specific damage of each object.
With the implementation of glass casting in France in the second half of the 17th century, larger mirrors could be produced. So-called tin-mercury mirrors were made by coating glass with tin amalgam. Today, many historical mirrors are partly damaged, the image quality is compromised, and the material integrity of the mirror is threatened. The transformation from tin into an oxide starts at the surface of the amalgam and proceeds down to the glass surface. The mercury dissolves as a liquid or gaseous phase. The amalgam layer is destroyed, so that conservation is necessary. Conservators must follow strict safety precautions while handling amalgam mirrors because of possible mercury emissions and corrosion of the amalgam, during which elemental mercury accumulates near the mirror frame in droplets and is emitted into the air.
In a research project, the quantity of the mercury emissions from historical mirrors was examined and a technique to decrease these emissions was developed.