Surface active elements of the iron melt such as sulphur, plays an important role in the formation of penetration surface defects. Higher sulphur levels in molding materials increases the fluidity of the melt on the metal-mould interface, helping the liquid metal to penetrate in the pores between the sand grains. The present work is a continuation of a previous work presented within this conference last year. The last year’s paper discussed both theoretical backgrounds of the penetration phenomena and discussed several introductory examinations.  The present work improves the previous results, comprehends penetration examinations of grey cast iron and ductile cast iron samples. As a result, it identifies the one of the most important factor occurring penetration surface defects, and reviews two separate types of solidification anomaly of cast iron caused by higher sulphur levels in molding material.