Oscillation marks are the most recognizable feature of continuous casting. They can be related to the subsurface defects. The physical surface defect of the oscillation marks themselves does not necessarily pose a significant problem in many grades. But many subsurface defects have been found to be associated with oscillation marks. The presence of oscillation marks and the related defects found on the surfaces of product rolled from cast slabs requires extra slab surface treatment.  Thus, if the defects related to oscillation mark formation can be eliminated, increased hot charging ratios would be possible.