Dross
		Manifestation: Irregularly shaped interruption in the material Typical characteristics: Dark scars, foamy dark surfaces, very finely distributed. Dross worsens the mechanical properties, especially the vibrostability which is reduced by up to 50% [1]. Dross mainly consists of magnesium oxy-silicates and magnesium sulphides, and is a product of the reaction of magnesium with oxygen, sulphur and silicon. Preferred defect locations: In the upper casting surface or beneath cores. Mostly in cast iron with nodular graphite, often only visible after the casting skin has been removed. Possible confusion/mistaken defect identification: Unknown Remedial measures: Dross cannot be prevented, only reduced. Melts: - High temperature regime - Low residual Mg contents - Clean melting of pure raw materials - Highly concentrated Mg master alloys or pure Mg - Double treatment - Gas purging - Little but effective inoculation - Adjust CE or Sc to the workpieces - Refining slags (melt cleaner) in the workpieces: - Draw off and restrain treatment slags (large pouring basin,   converter, optimum casting system) - Form filling rising, gentle and fast - Filters are very effective - Dry, closed moulds - HOT casting   Literature: [1] Kaufmann, H., Wolters, D.: Konstruieren und Gießen, No.1/2002; p. 4 to 27 Dross in a casting:               Effect of dross on the fatigue strength                                                    according to [1]    Dross: