The problem presented here was caused by an attempt to modify an alloy produced by a continuous casting process. This process worked well for a stainless steel with 20 wt% Cr and the manufacturer now wanted to use the same process for a steel with 25 wt% Cr. However, he then obtained problems with clogging by solid oxide formation which prevented the flow of liquid steel. The oxide formed at the outlet was found to consist mainly of Cr2O3. The manufacturer thus faced an expensive and time consuming experimental scheme in order to find out how to prevent the formation of this Cr2O3. As an alternative route he tried to use the Thermo-Calc thermodynamic databank in order to simulate the process on the computer in order to find out a remedy. Such a simulation can usually be made in less than a day if the necessary thermodynamic data are available.