Nondestructive testing for castings is most useful when the inspection question is clear. A buyer may need to detect surface-opening cracks, examine internal soundness or verify a particular region after machining. No single method answers every question equally well, and a request for NDT without further definition leaves too much uncertainty.

Surface roughness of investment castings should be specified where it affects function. A sealing face, a visible contour and an internal flow passage do not necessarily need the same finish. Applying one demanding value to the entire component can increase work while leaving the important surface requirement poorly defined.