Sand expansion defects like veining still rise to cost-intensive challenges for foundries due to rework or rejects. In this application, MIOX^® can be used as phenolic free core sand additive to reduce or avoid veining. The fundamental difference between MIOX^® and commonly used iron oxides is the platy structure of the product. Lab and field tests proved the positive influence on veining, better surface properties, reduced binder consumption and in some cases, casting even without core coatings.