Only a limited number of examples could be listed for demonstrating the influence of metallurgy and chemistry on working conditions. Actually, all work with metals is a practical application of these sciences. Melting and casting are the beginning of each working cycle. Greater emphasis was laid on this process. It becomes clear that with a limited number of measures, many defects can be avoided. The equally important process of deformation could not be considered in this presentation. Special effects in jewelry fabrication are connected with the solubility of oxygen in silver alloys, the reaction of platinum (and palladium) with refractory oxides, and the age-hardening process with gold-copper-silver alloys. Working with metals necessitates taking into account metallurgical and chemical properties all the time. It also necessitates considering the properties of the different matter that come in contact with the metal (atmosphere, investment, impurities, etc.). In the following discussion only a selection of influencing factors are considered. Some of them are more profoundly considered; others are only briefly mentioned because they have already been the subject of other more profound detailed presentations. More emphasis was laid on melting and casting processes in this presentation. The importance of a factor depends strongly on the type of alloy. Therefore, the three main types of jewelry alloys - silver, gold and platinum-based alloys - will be examined separately in a given situation. Sometimes it is very difficult to distinguish between metallurgical and chemical influences, e.g., with solubility of gases in a liquid alloy. For this reason a strict classification of influencing factors is not possible in many cases. Finally, the aim of the presentation is to offer some hints where problems and difficulties in processing jewelry alloys might be expected. It should be considered as a stimulation to open the mind for such problems.

Author: Dieter Ott