Black Stain

Technical Support

Struggling with a specific casting defect or just need general technical support?

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  • Very superficial black spots on a good and smooth casting

  • Indicates that the metal reacted with oxygen forming Chromium (Cr) and Manganese (Mn) oxides during melting, casting and solidification

Causes of this defect are evident in the metal and other portions of the process; to cure, R&R recommends taking the following actions:


High metal and mold temperatures.

Melt under Argon (Ar) blanket and adjust temperatures.


Turbulent casting.

Use a ceramic filter or carbon stucco.

Slow cooling down curve.

Separate molds after casting. Can molds after casting.