Place a coating thickness standard over the base metal standard and perform aminimum of 3 measurements on each coating thickness standard. The coatingthickness standard should be in the range of the required coating thickness of the partto be measured. The average readings must be within ± 0.1 mil (2.5 μm) or 5 percentwhichever is greater for eddy current instruments and ± 0.2 mil (5 μm) or 10 percentwhichever is greater for magnetic induction instruments. If the reading on theinstrument is not within this limit, it must be calibrated in accordance with themanufacturer's instructions. In addition, the thickness standard must be in good shape,no visual tears or large areas of indentations. After calibration the instrument must meetthe requirements in Section 7.1.a. and Section 7.1.b.