In May 2005 the Magnesite-Mine Breitenau, which is part of the Veitsch-Radex GmbH introduced a new site sensitized emulsion blasting system. In order to optimize the drilling and blasting pattern for this system, it became necessary to vary different blasting parameters like the drilling pattern, the detonater delay-time or the borehole geometry to find the most efficent settings. These tests lasted for about two months before a variation of the explosive consistence occurs. From this moment on, no further tests were undertaken, only some advance data like explosive consumption or the target/actual comparison of the pile mass were recorded. The reason for this variation was a wrong treatment of the base-emulsion, which is very sensitve on shear stresses. Due to these stresses the emulsion changed its viscosity and its blasting behaviour. The use of a more constant base-emulsion led to better blasting results. So the conclusion was, that not the blasting system, but the wrong treatment of the emulsion was responsible for the different blasting results