Clogging is a phenomenon which usually occurs in the flow control system during continuous casting. It describes the build-up of deposits at various positions in the continuous casting machine. The submerged entry nozzle (SEN) between tundish and mold is the area most frequently affected by the appearance of clogging. Certain steel grades, e.g. Ti-alloyed ULC steels, are especially known for their increased clogging tendency. Since the formation of non-metallic inclusions in the steel cannot be avoided completely, a deeper understanding of their development and behavior during secondary metallurgy and casting is required. Reactions in the tundish should possibly be used for inclusion removal through their separation from the liquid steel to the covering slag with a subsequent dissolution in the slag. Further, this includes the deposition of micro-inclusions to the steel/refractory interface in the submerged entry nozzle (SEN) between the tundish and the mold. For all these cases, interfacial properties of the system inclusion-steel-slag-refractory are believed to play a key role. Both, dissolution of inclusions in slag as well as adhesion of inclusion at the steel/refractory interface can be studied experimentally, primarily by means of HT-Laser Scanning Confocal Microscopy and Drop Shape Analysis. Additionally, a detailed model investigating fluid force-induced detachment criteria for inclusions adhered to a refractory/steel interface helps to define and investigate selective clogging sensitive cases. Finally, data (e.g. interfacial properties, viscosities) obtained in laboratory experiments should be used to provide metallurgical boundary conditions for numerical simulation approaches.