Years ago one of our first research projects in jewelry casting showed that gas inclusions are an important cause of porosity. Investigations have also shown that reactions with the investment lead to gas porosity. These results were not accepted at once by our colleagues. Trapped air, oxygen or humidity were thought to be the cause of gas porosity. In the meantime, these experimental results were confirmed and accepted. However, detailed investigations on the subject were missing. The aim of a more recent research project was to fill this gap. The subject was not restricted to gold jewelry alloys. Other alloys used for investment casting, such as dental alloys and titanium, were also considered. However, this paper deals only with the results concerned with gold jewelry alloys.

Author: Dieter Ott