Interpret the number against the right system

A multilayer reading may represent the total build without identifying the thickness or condition of each layer. The gauge method must suit the substrate and geometry. DeFelsko explains that coatings are intended to function within specified film ranges. That principle does not supply a MARSTON range, nor does it mean a value copied from another product can establish conformity of an unknown finish.

Assess properties that thickness cannot prove

Poor preparation, contamination or an unsuitable existing layer can affect protection even when the total build appears substantial. A localized thick area can also behave differently from a thin edge nearby. The specialist should determine whether separate continuity, adhesion or condition assessment is needed. Do not conduct a destructive adhesion test or remove coating without an approved scope and a plan to restore the affected protection.

If a thick central region passes while an edge remains poorly covered, the central result cannot resolve edge protection. Conversely, adding material everywhere to address one thin edge can create another issue. The specification and spatial findings should define the appropriate correction.

Choose acceptance from combined evidence

Ask which specification applies, which measurements were made and whether the evidence represents edges, joints and repaired areas as well as open faces. A single thick spot is not evidence for the whole component. If a defect is found, adding more paint may leave the cause unchanged. No MARSTON coating thickness, chemistry or environmental qualification is asserted; the responsible reviewer must connect each claimed property with relevant evidence.