Simulation of degradation phenomena on model enamels with historical compositions

Abstract

Enamels from arts and crafts objects of the Renaissance and Baroque period in Europe show an increasing and irreversible degradation caused by microclimatic environmental influences. In the present study typical degradation phenomena were simulated and the mechanisms of degradation were described. Model enamels on copper Substrates were produced and exposed to accelerated weathering in a climate Chamber. The enamel compositions were selected according to the analysis of Originals. The main part of the work was involved with the investigation of parameters influencing the corrosion of the objects like the effect of pollutants and changes of temperature and humidity. Besides, the influence of mechanical stresses in the enamel layer and the effect of a mechanical pre-damaging were parts of the working programme. The progress of the degradation process was followed by light microscopy and infrared reflectance spectroscopy. The investigations were completed by an assessment of the distribution of the stress in the enamel layer and the metal Substrate.