What is the minimum recommended distance away from an edge that an inspector should take a measurement with a dial-type magnetic pull-off Dry Film Thickness (DFT) gauge?

Fine cracks in the surface of a coating that rarely reach the substrate are called

You ate the NACE Inspector on a job where NACE No. 2/SSPC - SP 10 has been specified. You are finding the Contractor is leaving mill scale on the on surface and as a result you have been rejecting the blast. The Contractor is very upset and has told you that the standard permits up to 5% of the mill scale to remain and still be in be in compliance with the standard.
Your FIRST preferred course of action is to:

The least effective method of surface cleaning is most likely

SSPC SP 1 identifies the use of: