Coating thickness measuring instrument and methods

A method of measuring the thickness of a coating on a surface with a known average surface profile comprising the steps of:

• a. providing a coating thickness measuring instrument comprising:
• i. an electromagnetic probe for measuring the thickness of a coating applied to a surface and producing an output relating to the measured thickness;
• ii. a memory for storing calibration data;
• iii. a processor arranged to process the output produced by the probe, together with calibration data stored by the memory, to produce a calibrated coating thickness measurement value;
• iv. at least two sets of calibration data, obtained by making measurements on at least two surfaces with known, different average surface profiles, stored in the memory;
• and wherein each set of calibration data is associated with a different known average surface profile value, and wherein the processor receives a user selection of the set of calibration data to be used by the processor according to the average surface profile of the surface on which a measurement is to be made;
• b. selecting from the average surface profile values stored by the instrument in association with sets of calibration data the average surface profile value closest to the known average surface profile, thereby to select a set of calibration data to be used by the instrument;
• and
• c. using the instrument to measure coating thickness on the surface,
• wherein the processor receives the selection of the set of calibration data to be used by the instrument, and
• wherein the processor determines the calibrated coating thickness measurement value based on the output relating to the measured thickness produced by the electromagnetic probe and the selected set of calibration data.

A coating thickness measuring instrument comprising:

• a. an electromagnetic probe for measuring a thickness of a coating applied to a surface and producing an output relating to the measured thickness;
• b. a memory including pre-stored calibration data, the pre-stored calibration data including at least two sets of calibration data, each set associated with a different known average surface profile value;
• and
• c. a processor adapted to process data stored in the memory, to produce a calibrated coating thickness measurement value,
• wherein the processor receives a user selection of a set of calibration data to be used by the processor, and
• wherein the processor determines the calibrated coating thickness measurement value based on the output relating to the measured thickness produced by the electromagnetic probe and the set of calibration data selected by the user.