Simulation of degradation phenomena on model enamels with historical compositions

Enamels from arts and crafts objects of the Renaissance and Baroque period in Europe show an increasing and irreversible degradation caused by microcl imatic environmental influences. In the present study typical degradation p henomena were simulated and the mechanisms of degradation were described. M odel enamels on copper substrates were produced and exposed to accelerated weathering in a climate chamber. The enamel compositions were selected acco rding to the analysis of originals. The main part of the work was involved with the investigation of parameters influencing the corrosion of the objec ts like the effect of pollutants and changes of temperature and humidity. B esides, the influence of mechanical stresses in the enamel layer and the ef fect of a mechanical pre-damaging were parts of the working programme. The progress of the degradation process was followed by light microscopy and in frared reflectance spectroscopy. The investigations were completed by an as sessment of the distribution of the stress in the enamel layer and the meta l substrate.