TY - CONF A1 - Rikowski, Eckhard A1 - Adam, Karin A1 - Torge, Manfred T1 - Glass disease - special corrosion phenomena T2 - International Workshop "Non-destructive analysis and testing of museum objects", Intercollege CY - Nicosia, Cyprus DA - 2006-05-18 PY - 2006 AN - OPUS4-13238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rikowski, Eckhard A1 - Adam, Karin A1 - Torge, Manfred A1 - Wilke, Olaf A1 - Müller, W. T1 - Corrosion mechanisms and preventive conservation of baroque enamelled jewelleries T2 - Experts' Meeting on Enamel Conservation, Château de Germolles CY - Mellecey, France DA - 2006-07-01 PY - 2006 AN - OPUS4-13240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Römich, H. A1 - Jägers, E. A1 - Torge, Manfred A1 - Müller, Wolfgang A1 - Adam, Karin T1 - Cleaning - A balancing act N2 - This text originally appeared as chapter 5, 'Reinigung - Eine Gratwanderung' (pp. 101-28) in A. Wolff (ed.), Restaurierung und Konservierung historischer Glasmalereien, Mainz, 2000. Within the context of this research programme, scientists and conservators collaborated to assess various cleaning methods for historical stained glass. For cleaning glass surfaces there are the mechanical methods already being applied in most workshops, as well as the new chemical cleaning possibilities. Laboratory experiments were conducted initially on model glass in order to test the effectiveness and damage potential of these various methods; the model glass was examined both before and after cleaning by means of light microscopy and infra-red spectroscopy. In addition to this, cleaning tests were carried out on samples of original glass; electron-ray micro-analysis was also used to evaluate the results of these tests. The model-glass samples were corroded in advance by accelerated weathering in an attempt to simulate the damage seen on medieval glass. Enough model glass was prepared to allow any number of series of experiments to be carried out, in order to compare the effectiveness and suitability of the various chemical and mechanical methods and techniques. For the mechanical cleaning tests, a wide range of selected tools was tested by different conservators on pre-corroded model glass. This showed clearly that the success (or lack of it) of a cleaning episode was determined not just the choice of tool, but by the skill with which conservator wielded it. This observation was later confirmed by research on samples of original glass. Insensitive handling of tools or unsuitable tools could damage or completely destroy the gel layer. The gel layer should not be damaged, as this leads to increased levels of corrosion subsequently, though the encrustations should be reduced, as their hygroscopic qualities accelerate the corrosion processes. At the next stage, chemical cleaning methods were tested, and the results of cleaning with organic solvents (toluene, ethanol, acetone, etc.) and water-based solutions (oxalic acids, EDTA, ammoniac, etc.) compared with one another and evaluated. It became clear that strongly acidic and alkaline solutions, depending on the condition of the surface, could cause damage or have uncontrollable consequences. In the specific case of the glass from Erfurt Cathedral, for whose firmly fixed, very hard, opaque encrustations mechanical methods proved to be either ineffective or damaging to the glass, new chemical cleaning possibilities had to be found. Following comprehensive preliminary tests on model glass, various types of ion-exchanger and ammonium-carbonate solution were chosen. Both methods were successful in improving the transparency of some (but not all) of the samples. The experiments with the original material from Erfurt Cathedral clearly showed that successful cleaning was dependent on the particular composition of the encrustation. Really gentle cleaning can be achieved by chemical means, though only when the chemical agents are tailored to individual damage situations; this can only be achieved when scientific analysis is undertaken in tandem with the cleaning processes. The assessment of these mechanical and chemical cleaning methods was oriented towards treating corrosion on sensitive medieval glass. Nineteenth-century glass is generally less sensitive, though cleaning of this material must also be careful and very gentle. Scientific analysis alone is not enough to determine the choice of cleaning method, but can act as an aid to the conservator in selecting the right cleaning agent and method. KW - Historische Glasmalereien KW - Restaurierung PY - 2006 UR - http://www.cvma.ac.uk/conserv/cleaning.html SP - 1 EP - 33 PB - Kings's College CY - London AN - OPUS4-12308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -